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1 @c -*-texinfo-*-
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2 @c This is part of the XEmacs Lisp Reference Manual.
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3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
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4 @c See the file lispref.texi for copying conditions.
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5 @setfilename ../../info/files.info
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6 @node Files, Backups and Auto-Saving, Documentation, Top
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7 @chapter Files
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8
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9 In XEmacs, you can find, create, view, save, and otherwise work with
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10 files and file directories. This chapter describes most of the
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11 file-related functions of XEmacs Lisp, but a few others are described in
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12 @ref{Buffers}, and those related to backups and auto-saving are
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13 described in @ref{Backups and Auto-Saving}.
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14
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15 Many of the file functions take one or more arguments that are file
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16 names. A file name is actually a string. Most of these functions
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17 expand file name arguments using @code{expand-file-name}, so that
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18 @file{~} is handled correctly, as are relative file names (including
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19 @samp{../}). These functions don't recognize environment variable
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20 substitutions such as @samp{$HOME}. @xref{File Name Expansion}.
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21
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22 @menu
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23 * Visiting Files:: Reading files into Emacs buffers for editing.
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24 * Saving Buffers:: Writing changed buffers back into files.
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25 * Reading from Files:: Reading files into buffers without visiting.
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26 * Writing to Files:: Writing new files from parts of buffers.
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27 * File Locks:: Locking and unlocking files, to prevent
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28 simultaneous editing by two people.
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29 * Information about Files:: Testing existence, accessibility, size of files.
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30 * Changing File Attributes:: Renaming files, changing protection, etc.
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31 * File Names:: Decomposing and expanding file names.
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32 * Contents of Directories:: Getting a list of the files in a directory.
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33 * Create/Delete Dirs:: Creating and Deleting Directories.
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34 * Magic File Names:: Defining "magic" special handling
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35 for certain file names.
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36 * Partial Files:: Treating a section of a buffer as a file.
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37 * Format Conversion:: Conversion to and from various file formats.
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38 * Files and MS-DOS:: Distinguishing text and binary files on MS-DOS.
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39 @end menu
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40
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41 @node Visiting Files
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42 @section Visiting Files
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43 @cindex finding files
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44 @cindex visiting files
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45
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46 Visiting a file means reading a file into a buffer. Once this is
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47 done, we say that the buffer is @dfn{visiting} that file, and call the
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48 file ``the visited file'' of the buffer.
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49
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50 A file and a buffer are two different things. A file is information
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51 recorded permanently in the computer (unless you delete it). A buffer,
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52 on the other hand, is information inside of XEmacs that will vanish at
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53 the end of the editing session (or when you kill the buffer). Usually,
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54 a buffer contains information that you have copied from a file; then we
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55 say the buffer is visiting that file. The copy in the buffer is what
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56 you modify with editing commands. Such changes to the buffer do not
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57 change the file; therefore, to make the changes permanent, you must
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58 @dfn{save} the buffer, which means copying the altered buffer contents
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59 back into the file.
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60
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61 In spite of the distinction between files and buffers, people often
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62 refer to a file when they mean a buffer and vice-versa. Indeed, we say,
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63 ``I am editing a file,'' rather than, ``I am editing a buffer that I
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64 will soon save as a file of the same name.'' Humans do not usually need
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65 to make the distinction explicit. When dealing with a computer program,
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66 however, it is good to keep the distinction in mind.
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67
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68 @menu
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69 * Visiting Functions:: The usual interface functions for visiting.
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70 * Subroutines of Visiting:: Lower-level subroutines that they use.
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71 @end menu
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72
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73 @node Visiting Functions
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74 @subsection Functions for Visiting Files
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75
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76 This section describes the functions normally used to visit files.
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77 For historical reasons, these functions have names starting with
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78 @samp{find-} rather than @samp{visit-}. @xref{Buffer File Name}, for
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79 functions and variables that access the visited file name of a buffer or
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80 that find an existing buffer by its visited file name.
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81
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82 In a Lisp program, if you want to look at the contents of a file but
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83 not alter it, the fastest way is to use @code{insert-file-contents} in a
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84 temporary buffer. Visiting the file is not necessary and takes longer.
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85 @xref{Reading from Files}.
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86
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87 @deffn Command find-file filename
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88 This command selects a buffer visiting the file @var{filename},
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89 using an existing buffer if there is one, and otherwise creating a
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90 new buffer and reading the file into it. It also returns that buffer.
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91
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92 The body of the @code{find-file} function is very simple and looks
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93 like this:
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94
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95 @example
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96 (switch-to-buffer (find-file-noselect filename))
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97 @end example
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98
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99 @noindent
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100 (See @code{switch-to-buffer} in @ref{Displaying Buffers}.)
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101
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102 When @code{find-file} is called interactively, it prompts for
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103 @var{filename} in the minibuffer.
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104 @end deffn
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105
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106 @defun find-file-noselect filename &optional nowarn
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107 This function is the guts of all the file-visiting functions. It finds
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108 or creates a buffer visiting the file @var{filename}, and returns it.
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109 It uses an existing buffer if there is one, and otherwise creates a new
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110 buffer and reads the file into it. You may make the buffer current or
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111 display it in a window if you wish, but this function does not do so.
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112
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113 When @code{find-file-noselect} uses an existing buffer, it first
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114 verifies that the file has not changed since it was last visited or
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115 saved in that buffer. If the file has changed, then this function asks
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116 the user whether to reread the changed file. If the user says
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117 @samp{yes}, any changes previously made in the buffer are lost.
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118
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119 If @code{find-file-noselect} needs to create a buffer, and there is no
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120 file named @var{filename}, it displays the message @samp{New file} in
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121 the echo area, and leaves the buffer empty.
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122
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123 @c XEmacs feature
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124 If @var{nowarn} is non-@code{nil}, various warnings that XEmacs normally
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125 gives (e.g. if another buffer is already visiting @var{filename} but
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126 @var{filename} has been removed from disk since that buffer was created)
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127 are suppressed.
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128
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129 The @code{find-file-noselect} function calls @code{after-find-file}
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130 after reading the file (@pxref{Subroutines of Visiting}). That function
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131 sets the buffer major mode, parses local variables, warns the user if
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132 there exists an auto-save file more recent than the file just visited,
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133 and finishes by running the functions in @code{find-file-hooks}.
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134
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135 The @code{find-file-noselect} function returns the buffer that is
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136 visiting the file @var{filename}.
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137
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138 @example
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139 @group
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140 (find-file-noselect "/etc/fstab")
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141 @result{} #<buffer fstab>
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142 @end group
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143 @end example
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144 @end defun
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145
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146 @deffn Command find-file-other-window filename
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147 This command selects a buffer visiting the file @var{filename}, but
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148 does so in a window other than the selected window. It may use another
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149 existing window or split a window; see @ref{Displaying Buffers}.
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150
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151 When this command is called interactively, it prompts for
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152 @var{filename}.
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153 @end deffn
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154
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155 @deffn Command find-file-read-only filename
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156 This command selects a buffer visiting the file @var{filename}, like
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157 @code{find-file}, but it marks the buffer as read-only. @xref{Read Only
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158 Buffers}, for related functions and variables.
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159
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160 When this command is called interactively, it prompts for
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161 @var{filename}.
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162 @end deffn
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163
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164 @deffn Command view-file filename &optional other-window-p
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165 This command visits @var{filename} in View mode, and displays it in a
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166 recursive edit, returning to the previous buffer when done. View mode
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167 is a mode that allows you to skim rapidly through the file but does not
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168 let you modify it. Entering View mode runs the normal hook
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169 @code{view-mode-hook}. @xref{Hooks}.
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170
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171 When @code{view-file} is called interactively, it prompts for
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172 @var{filename}.
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173
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174 With non-@code{nil} prefix arg @var{other-window-p}, visit @var{filename}
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175 in another window.
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176 @end deffn
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177
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178 @defvar find-file-hooks
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179 The value of this variable is a list of functions to be called after a
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180 file is visited. The file's local-variables specification (if any) will
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181 have been processed before the hooks are run. The buffer visiting the
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182 file is current when the hook functions are run.
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183
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184 This variable works just like a normal hook, but we think that renaming
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185 it would not be advisable.
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186 @end defvar
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187
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188 @defvar find-file-not-found-hooks
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189 The value of this variable is a list of functions to be called when
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190 @code{find-file} or @code{find-file-noselect} is passed a nonexistent
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191 file name. @code{find-file-noselect} calls these functions as soon as
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192 it detects a nonexistent file. It calls them in the order of the list,
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193 until one of them returns non-@code{nil}. @code{buffer-file-name} is
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194 already set up.
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195
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196 This is not a normal hook because the values of the functions are
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197 used and they may not all be called.
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198 @end defvar
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199
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200 @node Subroutines of Visiting
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201 @subsection Subroutines of Visiting
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202
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203 The @code{find-file-noselect} function uses the
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204 @code{create-file-buffer} and @code{after-find-file} functions as
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205 subroutines. Sometimes it is useful to call them directly.
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206
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207 @defun create-file-buffer filename
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208 This function creates a suitably named buffer for visiting
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209 @var{filename}, and returns it. It uses @var{filename} (sans directory)
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210 as the name if that name is free; otherwise, it appends a string such as
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211 @samp{<2>} to get an unused name. See also @ref{Creating Buffers}.
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212
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213 @strong{Please note:} @code{create-file-buffer} does @emph{not}
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214 associate the new buffer with a file and does not select the buffer.
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215 It also does not use the default major mode.
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216
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217 @example
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218 @group
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219 (create-file-buffer "foo")
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220 @result{} #<buffer foo>
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221 @end group
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222 @group
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223 (create-file-buffer "foo")
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224 @result{} #<buffer foo<2>>
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225 @end group
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226 @group
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227 (create-file-buffer "foo")
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228 @result{} #<buffer foo<3>>
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229 @end group
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230 @end example
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231
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232 This function is used by @code{find-file-noselect}.
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233 It uses @code{generate-new-buffer} (@pxref{Creating Buffers}).
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234 @end defun
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235
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236 @defun after-find-file &optional error warn noauto
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237 This function sets the buffer major mode, and parses local variables
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238 (@pxref{Auto Major Mode}). It is called by @code{find-file-noselect}
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239 and by the default revert function (@pxref{Reverting}).
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240
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241 @cindex new file message
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242 @cindex file open error
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243 If reading the file got an error because the file does not exist, but
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244 its directory does exist, the caller should pass a non-@code{nil} value
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245 for @var{error}. In that case, @code{after-find-file} issues a warning:
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246 @samp{(New File)}. For more serious errors, the caller should usually not
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247 call @code{after-find-file}.
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248
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249 If @var{warn} is non-@code{nil}, then this function issues a warning
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250 if an auto-save file exists and is more recent than the visited file.
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251
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252 @c XEmacs feature
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253 If @var{noauto} is non-@code{nil}, then this function does not turn
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254 on auto-save mode; otherwise, it does.
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255
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256 The last thing @code{after-find-file} does is call all the functions
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257 in @code{find-file-hooks}.
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258 @end defun
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259
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260 @node Saving Buffers
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261 @section Saving Buffers
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262
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263 When you edit a file in XEmacs, you are actually working on a buffer
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264 that is visiting that file---that is, the contents of the file are
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265 copied into the buffer and the copy is what you edit. Changes to the
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266 buffer do not change the file until you @dfn{save} the buffer, which
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267 means copying the contents of the buffer into the file.
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268
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269 @deffn Command save-buffer &optional backup-option
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270 This function saves the contents of the current buffer in its visited
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271 file if the buffer has been modified since it was last visited or saved.
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272 Otherwise it does nothing.
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273
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274 @code{save-buffer} is responsible for making backup files. Normally,
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275 @var{backup-option} is @code{nil}, and @code{save-buffer} makes a backup
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276 file only if this is the first save since visiting the file. Other
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277 values for @var{backup-option} request the making of backup files in
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278 other circumstances:
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279
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280 @itemize @bullet
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281 @item
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282 With an argument of 4 or 64, reflecting 1 or 3 @kbd{C-u}'s, the
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283 @code{save-buffer} function marks this version of the file to be
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284 backed up when the buffer is next saved.
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285
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286 @item
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287 With an argument of 16 or 64, reflecting 2 or 3 @kbd{C-u}'s, the
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288 @code{save-buffer} function unconditionally backs up the previous
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289 version of the file before saving it.
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290 @end itemize
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291 @end deffn
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292
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293 @deffn Command save-some-buffers &optional save-silently-p exiting
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294 This command saves some modified file-visiting buffers. Normally it
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295 asks the user about each buffer. But if @var{save-silently-p} is
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296 non-@code{nil}, it saves all the file-visiting buffers without querying
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297 the user.
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298
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299 The optional @var{exiting} argument, if non-@code{nil}, requests this
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300 function to offer also to save certain other buffers that are not
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301 visiting files. These are buffers that have a non-@code{nil} local
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302 value of @code{buffer-offer-save}. (A user who says yes to saving one
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303 of these is asked to specify a file name to use.) The
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304 @code{save-buffers-kill-emacs} function passes a non-@code{nil} value
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305 for this argument.
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306 @end deffn
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307
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308 @defvar buffer-offer-save
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309 When this variable is non-@code{nil} in a buffer, XEmacs offers to save
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310 the buffer on exit even if the buffer is not visiting a file. The
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311 variable is automatically local in all buffers. Normally, Mail mode
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312 (used for editing outgoing mail) sets this to @code{t}.
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313 @end defvar
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314
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315 @deffn Command write-file filename
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316 This function writes the current buffer into file @var{filename}, makes
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317 the buffer visit that file, and marks it not modified. Then it renames
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318 the buffer based on @var{filename}, appending a string like @samp{<2>}
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319 if necessary to make a unique buffer name. It does most of this work by
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320 calling @code{set-visited-file-name} and @code{save-buffer}.
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321 @end deffn
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322
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323 @defvar write-file-hooks
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324 The value of this variable is a list of functions to be called before
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325 writing out a buffer to its visited file. If one of them returns
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326 non-@code{nil}, the file is considered already written and the rest of
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327 the functions are not called, nor is the usual code for writing the file
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328 executed.
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329
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330 If a function in @code{write-file-hooks} returns non-@code{nil}, it
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331 is responsible for making a backup file (if that is appropriate).
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332 To do so, execute the following code:
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333
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334 @example
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335 (or buffer-backed-up (backup-buffer))
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336 @end example
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337
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338 You might wish to save the file modes value returned by
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339 @code{backup-buffer} and use that to set the mode bits of the file that
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340 you write. This is what @code{save-buffer} normally does.
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341
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342 Even though this is not a normal hook, you can use @code{add-hook} and
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343 @code{remove-hook} to manipulate the list. @xref{Hooks}.
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344 @end defvar
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345
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346 @c Emacs 19 feature
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347 @defvar local-write-file-hooks
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348 This works just like @code{write-file-hooks}, but it is intended
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349 to be made local to particular buffers. It's not a good idea to make
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350 @code{write-file-hooks} local to a buffer---use this variable instead.
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351
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352 The variable is marked as a permanent local, so that changing the major
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353 mode does not alter a buffer-local value. This is convenient for
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354 packages that read ``file'' contents in special ways, and set up hooks
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355 to save the data in a corresponding way.
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356 @end defvar
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357
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358 @c Emacs 19 feature
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359 @defvar write-contents-hooks
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360 This works just like @code{write-file-hooks}, but it is intended for
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361 hooks that pertain to the contents of the file, as opposed to hooks that
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362 pertain to where the file came from. Such hooks are usually set up by
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363 major modes, as buffer-local bindings for this variable. Switching to a
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364 new major mode always resets this variable.
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365 @end defvar
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366
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367 @c Emacs 19 feature
|
|
|
368 @defvar after-save-hook
|
|
|
369 This normal hook runs after a buffer has been saved in its visited file.
|
|
|
370 @end defvar
|
|
|
371
|
|
|
372 @defvar file-precious-flag
|
|
|
373 If this variable is non-@code{nil}, then @code{save-buffer} protects
|
|
|
374 against I/O errors while saving by writing the new file to a temporary
|
|
|
375 name instead of the name it is supposed to have, and then renaming it to
|
|
|
376 the intended name after it is clear there are no errors. This procedure
|
|
|
377 prevents problems such as a lack of disk space from resulting in an
|
|
|
378 invalid file.
|
|
|
379
|
|
|
380 As a side effect, backups are necessarily made by copying. @xref{Rename
|
|
|
381 or Copy}. Yet, at the same time, saving a precious file always breaks
|
|
|
382 all hard links between the file you save and other file names.
|
|
|
383
|
|
|
384 Some modes set this variable non-@code{nil} locally in particular
|
|
|
385 buffers.
|
|
|
386 @end defvar
|
|
|
387
|
|
|
388 @defopt require-final-newline
|
|
|
389 This variable determines whether files may be written out that do
|
|
|
390 @emph{not} end with a newline. If the value of the variable is
|
|
|
391 @code{t}, then @code{save-buffer} silently adds a newline at the end of
|
|
|
392 the file whenever the buffer being saved does not already end in one.
|
|
|
393 If the value of the variable is non-@code{nil}, but not @code{t}, then
|
|
|
394 @code{save-buffer} asks the user whether to add a newline each time the
|
|
|
395 case arises.
|
|
|
396
|
|
|
397 If the value of the variable is @code{nil}, then @code{save-buffer}
|
|
|
398 doesn't add newlines at all. @code{nil} is the default value, but a few
|
|
|
399 major modes set it to @code{t} in particular buffers.
|
|
|
400 @end defopt
|
|
|
401
|
|
|
402 @node Reading from Files
|
|
|
403 @section Reading from Files
|
|
|
404
|
|
|
405 You can copy a file from the disk and insert it into a buffer
|
|
|
406 using the @code{insert-file-contents} function. Don't use the user-level
|
|
|
407 command @code{insert-file} in a Lisp program, as that sets the mark.
|
|
|
408
|
|
444
|
409 @defun insert-file-contents filename &optional visit start end replace
|
|
428
|
410 This function inserts the contents of file @var{filename} into the
|
|
|
411 current buffer after point. It returns a list of the absolute file name
|
|
|
412 and the length of the data inserted. An error is signaled if
|
|
|
413 @var{filename} is not the name of a file that can be read.
|
|
|
414
|
|
|
415 The function @code{insert-file-contents} checks the file contents
|
|
|
416 against the defined file formats, and converts the file contents if
|
|
|
417 appropriate. @xref{Format Conversion}. It also calls the functions in
|
|
|
418 the list @code{after-insert-file-functions}; see @ref{Saving
|
|
|
419 Properties}.
|
|
|
420
|
|
|
421 If @var{visit} is non-@code{nil}, this function additionally marks the
|
|
|
422 buffer as unmodified and sets up various fields in the buffer so that it
|
|
|
423 is visiting the file @var{filename}: these include the buffer's visited
|
|
|
424 file name and its last save file modtime. This feature is used by
|
|
|
425 @code{find-file-noselect} and you probably should not use it yourself.
|
|
|
426
|
|
444
|
427 If @var{start} and @var{end} are non-@code{nil}, they should be integers
|
|
428
|
428 specifying the portion of the file to insert. In this case, @var{visit}
|
|
|
429 must be @code{nil}. For example,
|
|
|
430
|
|
|
431 @example
|
|
|
432 (insert-file-contents filename nil 0 500)
|
|
|
433 @end example
|
|
|
434
|
|
|
435 @noindent
|
|
|
436 inserts the first 500 characters of a file.
|
|
|
437
|
|
|
438 If the argument @var{replace} is non-@code{nil}, it means to replace the
|
|
|
439 contents of the buffer (actually, just the accessible portion) with the
|
|
|
440 contents of the file. This is better than simply deleting the buffer
|
|
|
441 contents and inserting the whole file, because (1) it preserves some
|
|
|
442 marker positions and (2) it puts less data in the undo list.
|
|
|
443 @end defun
|
|
|
444
|
|
|
445 If you want to pass a file name to another process so that another
|
|
|
446 program can read the file, use the function @code{file-local-copy}; see
|
|
|
447 @ref{Magic File Names}.
|
|
|
448
|
|
|
449 @node Writing to Files
|
|
|
450 @section Writing to Files
|
|
|
451
|
|
|
452 You can write the contents of a buffer, or part of a buffer, directly
|
|
|
453 to a file on disk using the @code{append-to-file} and
|
|
|
454 @code{write-region} functions. Don't use these functions to write to
|
|
|
455 files that are being visited; that could cause confusion in the
|
|
|
456 mechanisms for visiting.
|
|
|
457
|
|
|
458 @deffn Command append-to-file start end filename
|
|
|
459 This function appends the contents of the region delimited by
|
|
|
460 @var{start} and @var{end} in the current buffer to the end of file
|
|
|
461 @var{filename}. If that file does not exist, it is created. If that
|
|
|
462 file exists it is overwritten. This function returns @code{nil}.
|
|
|
463
|
|
|
464 An error is signaled if @var{filename} specifies a nonwritable file,
|
|
|
465 or a nonexistent file in a directory where files cannot be created.
|
|
|
466 @end deffn
|
|
|
467
|
|
|
468 @deffn Command write-region start end filename &optional append visit
|
|
|
469 This function writes the region delimited by @var{start} and @var{end}
|
|
|
470 in the current buffer into the file specified by @var{filename}.
|
|
|
471
|
|
|
472 @c Emacs 19 feature
|
|
|
473 If @var{start} is a string, then @code{write-region} writes or appends
|
|
|
474 that string, rather than text from the buffer.
|
|
|
475
|
|
|
476 If @var{append} is non-@code{nil}, then the specified text is appended
|
|
|
477 to the existing file contents (if any).
|
|
|
478
|
|
|
479 If @var{visit} is @code{t}, then XEmacs establishes an association
|
|
|
480 between the buffer and the file: the buffer is then visiting that file.
|
|
|
481 It also sets the last file modification time for the current buffer to
|
|
|
482 @var{filename}'s modtime, and marks the buffer as not modified. This
|
|
|
483 feature is used by @code{save-buffer}, but you probably should not use
|
|
|
484 it yourself.
|
|
|
485
|
|
|
486 @c Emacs 19 feature
|
|
|
487 If @var{visit} is a string, it specifies the file name to visit. This
|
|
|
488 way, you can write the data to one file (@var{filename}) while recording
|
|
|
489 the buffer as visiting another file (@var{visit}). The argument
|
|
|
490 @var{visit} is used in the echo area message and also for file locking;
|
|
|
491 @var{visit} is stored in @code{buffer-file-name}. This feature is used
|
|
|
492 to implement @code{file-precious-flag}; don't use it yourself unless you
|
|
|
493 really know what you're doing.
|
|
|
494
|
|
|
495 The function @code{write-region} converts the data which it writes to
|
|
|
496 the appropriate file formats specified by @code{buffer-file-format}.
|
|
|
497 @xref{Format Conversion}. It also calls the functions in the list
|
|
|
498 @code{write-region-annotate-functions}; see @ref{Saving Properties}.
|
|
|
499
|
|
|
500 Normally, @code{write-region} displays a message @samp{Wrote file
|
|
|
501 @var{filename}} in the echo area. If @var{visit} is neither @code{t}
|
|
|
502 nor @code{nil} nor a string, then this message is inhibited. This
|
|
|
503 feature is useful for programs that use files for internal purposes,
|
|
|
504 files that the user does not need to know about.
|
|
|
505 @end deffn
|
|
|
506
|
|
|
507 @node File Locks
|
|
|
508 @section File Locks
|
|
|
509 @cindex file locks
|
|
|
510
|
|
|
511 When two users edit the same file at the same time, they are likely to
|
|
|
512 interfere with each other. XEmacs tries to prevent this situation from
|
|
|
513 arising by recording a @dfn{file lock} when a file is being modified.
|
|
|
514 XEmacs can then detect the first attempt to modify a buffer visiting a
|
|
|
515 file that is locked by another XEmacs process, and ask the user what to do.
|
|
|
516
|
|
|
517 File locks do not work properly when multiple machines can share
|
|
|
518 file systems, such as with NFS. Perhaps a better file locking system
|
|
|
519 will be implemented in the future. When file locks do not work, it is
|
|
|
520 possible for two users to make changes simultaneously, but XEmacs can
|
|
|
521 still warn the user who saves second. Also, the detection of
|
|
|
522 modification of a buffer visiting a file changed on disk catches some
|
|
|
523 cases of simultaneous editing; see @ref{Modification Time}.
|
|
|
524
|
|
|
525 @c Not optional in FSF Emacs 19
|
|
|
526 @defun file-locked-p &optional filename
|
|
|
527 This function returns @code{nil} if the file @var{filename} is not
|
|
|
528 locked by this XEmacs process. It returns @code{t} if it is locked by
|
|
|
529 this XEmacs, and it returns the name of the user who has locked it if it
|
|
|
530 is locked by someone else.
|
|
|
531
|
|
|
532 @example
|
|
|
533 @group
|
|
|
534 (file-locked-p "foo")
|
|
|
535 @result{} nil
|
|
|
536 @end group
|
|
|
537 @end example
|
|
|
538 @end defun
|
|
|
539
|
|
|
540 @defun lock-buffer &optional filename
|
|
|
541 This function locks the file @var{filename}, if the current buffer is
|
|
|
542 modified. The argument @var{filename} defaults to the current buffer's
|
|
|
543 visited file. Nothing is done if the current buffer is not visiting a
|
|
|
544 file, or is not modified.
|
|
|
545 @end defun
|
|
|
546
|
|
|
547 @defun unlock-buffer
|
|
|
548 This function unlocks the file being visited in the current buffer,
|
|
|
549 if the buffer is modified. If the buffer is not modified, then
|
|
|
550 the file should not be locked, so this function does nothing. It also
|
|
|
551 does nothing if the current buffer is not visiting a file.
|
|
|
552 @end defun
|
|
|
553
|
|
444
|
554 @defun ask-user-about-lock filename other-user
|
|
|
555 This function is called when the user tries to modify @var{filename},
|
|
|
556 but it is locked by another user named @var{other-user}. The value it
|
|
|
557 returns determines what happens next:
|
|
428
|
558
|
|
|
559 @itemize @bullet
|
|
|
560 @item
|
|
|
561 A value of @code{t} says to grab the lock on the file. Then
|
|
|
562 this user may edit the file and @var{other-user} loses the lock.
|
|
|
563
|
|
|
564 @item
|
|
|
565 A value of @code{nil} says to ignore the lock and let this
|
|
|
566 user edit the file anyway.
|
|
|
567
|
|
|
568 @item
|
|
|
569 @kindex file-locked
|
|
|
570 This function may instead signal a @code{file-locked} error, in which
|
|
|
571 case the change that the user was about to make does not take place.
|
|
|
572
|
|
|
573 The error message for this error looks like this:
|
|
|
574
|
|
|
575 @example
|
|
444
|
576 @error{} File is locked: @var{filename} @var{other-user}
|
|
428
|
577 @end example
|
|
|
578
|
|
|
579 @noindent
|
|
444
|
580 where @var{filename} is the name of the file and @var{other-user} is the
|
|
428
|
581 name of the user who has locked the file.
|
|
|
582 @end itemize
|
|
|
583
|
|
|
584 The default definition of this function asks the user to choose what
|
|
|
585 to do. If you wish, you can replace the @code{ask-user-about-lock}
|
|
|
586 function with your own version that decides in another way. The code
|
|
|
587 for its usual definition is in @file{userlock.el}.
|
|
|
588 @end defun
|
|
|
589
|
|
|
590 @node Information about Files
|
|
|
591 @section Information about Files
|
|
|
592
|
|
|
593 The functions described in this section all operate on strings that
|
|
|
594 designate file names. All the functions have names that begin with the
|
|
|
595 word @samp{file}. These functions all return information about actual
|
|
|
596 files or directories, so their arguments must all exist as actual files
|
|
|
597 or directories unless otherwise noted.
|
|
|
598
|
|
|
599 @menu
|
|
|
600 * Testing Accessibility:: Is a given file readable? Writable?
|
|
|
601 * Kinds of Files:: Is it a directory? A symbolic link?
|
|
|
602 * Truenames:: Eliminating symbolic links from a file name.
|
|
|
603 * File Attributes:: How large is it? Any other names? Etc.
|
|
|
604 @end menu
|
|
|
605
|
|
|
606 @node Testing Accessibility
|
|
|
607 @subsection Testing Accessibility
|
|
|
608 @cindex accessibility of a file
|
|
|
609 @cindex file accessibility
|
|
|
610
|
|
|
611 These functions test for permission to access a file in specific ways.
|
|
|
612
|
|
|
613 @defun file-exists-p filename
|
|
|
614 This function returns @code{t} if a file named @var{filename} appears
|
|
|
615 to exist. This does not mean you can necessarily read the file, only
|
|
|
616 that you can find out its attributes. (On Unix, this is true if the
|
|
|
617 file exists and you have execute permission on the containing
|
|
|
618 directories, regardless of the protection of the file itself.)
|
|
|
619
|
|
|
620 If the file does not exist, or if fascist access control policies
|
|
|
621 prevent you from finding the attributes of the file, this function
|
|
|
622 returns @code{nil}.
|
|
|
623 @end defun
|
|
|
624
|
|
|
625 @defun file-readable-p filename
|
|
|
626 This function returns @code{t} if a file named @var{filename} exists
|
|
|
627 and you can read it. It returns @code{nil} otherwise.
|
|
|
628
|
|
|
629 @example
|
|
|
630 @group
|
|
|
631 (file-readable-p "files.texi")
|
|
|
632 @result{} t
|
|
|
633 @end group
|
|
|
634 @group
|
|
|
635 (file-exists-p "/usr/spool/mqueue")
|
|
|
636 @result{} t
|
|
|
637 @end group
|
|
|
638 @group
|
|
|
639 (file-readable-p "/usr/spool/mqueue")
|
|
|
640 @result{} nil
|
|
|
641 @end group
|
|
|
642 @end example
|
|
|
643 @end defun
|
|
|
644
|
|
|
645 @c Emacs 19 feature
|
|
|
646 @defun file-executable-p filename
|
|
|
647 This function returns @code{t} if a file named @var{filename} exists and
|
|
|
648 you can execute it. It returns @code{nil} otherwise. If the file is a
|
|
|
649 directory, execute permission means you can check the existence and
|
|
|
650 attributes of files inside the directory, and open those files if their
|
|
|
651 modes permit.
|
|
|
652 @end defun
|
|
|
653
|
|
|
654 @defun file-writable-p filename
|
|
|
655 This function returns @code{t} if the file @var{filename} can be written
|
|
|
656 or created by you, and @code{nil} otherwise. A file is writable if the
|
|
|
657 file exists and you can write it. It is creatable if it does not exist,
|
|
|
658 but the specified directory does exist and you can write in that
|
|
|
659 directory.
|
|
|
660
|
|
|
661 In the third example below, @file{foo} is not writable because the
|
|
|
662 parent directory does not exist, even though the user could create such
|
|
|
663 a directory.
|
|
|
664
|
|
|
665 @example
|
|
|
666 @group
|
|
|
667 (file-writable-p "~/foo")
|
|
|
668 @result{} t
|
|
|
669 @end group
|
|
|
670 @group
|
|
|
671 (file-writable-p "/foo")
|
|
|
672 @result{} nil
|
|
|
673 @end group
|
|
|
674 @group
|
|
|
675 (file-writable-p "~/no-such-dir/foo")
|
|
|
676 @result{} nil
|
|
|
677 @end group
|
|
|
678 @end example
|
|
|
679 @end defun
|
|
|
680
|
|
|
681 @c Emacs 19 feature
|
|
|
682 @defun file-accessible-directory-p dirname
|
|
|
683 This function returns @code{t} if you have permission to open existing
|
|
|
684 files in the directory whose name as a file is @var{dirname}; otherwise
|
|
|
685 (or if there is no such directory), it returns @code{nil}. The value
|
|
|
686 of @var{dirname} may be either a directory name or the file name of a
|
|
|
687 directory.
|
|
|
688
|
|
|
689 Example: after the following,
|
|
|
690
|
|
|
691 @example
|
|
|
692 (file-accessible-directory-p "/foo")
|
|
|
693 @result{} nil
|
|
|
694 @end example
|
|
|
695
|
|
|
696 @noindent
|
|
|
697 we can deduce that any attempt to read a file in @file{/foo/} will
|
|
|
698 give an error.
|
|
|
699 @end defun
|
|
|
700
|
|
|
701 @defun file-ownership-preserved-p filename
|
|
|
702 This function returns @code{t} if deleting the file @var{filename} and
|
|
|
703 then creating it anew would keep the file's owner unchanged.
|
|
|
704 @end defun
|
|
|
705
|
|
|
706 @defun file-newer-than-file-p filename1 filename2
|
|
|
707 @cindex file age
|
|
|
708 @cindex file modification time
|
|
|
709 This function returns @code{t} if the file @var{filename1} is
|
|
|
710 newer than file @var{filename2}. If @var{filename1} does not
|
|
|
711 exist, it returns @code{nil}. If @var{filename2} does not exist,
|
|
|
712 it returns @code{t}.
|
|
|
713
|
|
|
714 In the following example, assume that the file @file{aug-19} was written
|
|
|
715 on the 19th, @file{aug-20} was written on the 20th, and the file
|
|
|
716 @file{no-file} doesn't exist at all.
|
|
|
717
|
|
|
718 @example
|
|
|
719 @group
|
|
|
720 (file-newer-than-file-p "aug-19" "aug-20")
|
|
|
721 @result{} nil
|
|
|
722 @end group
|
|
|
723 @group
|
|
|
724 (file-newer-than-file-p "aug-20" "aug-19")
|
|
|
725 @result{} t
|
|
|
726 @end group
|
|
|
727 @group
|
|
|
728 (file-newer-than-file-p "aug-19" "no-file")
|
|
|
729 @result{} t
|
|
|
730 @end group
|
|
|
731 @group
|
|
|
732 (file-newer-than-file-p "no-file" "aug-19")
|
|
|
733 @result{} nil
|
|
|
734 @end group
|
|
|
735 @end example
|
|
|
736
|
|
|
737 You can use @code{file-attributes} to get a file's last modification
|
|
|
738 time as a list of two numbers. @xref{File Attributes}.
|
|
|
739 @end defun
|
|
|
740
|
|
|
741 @node Kinds of Files
|
|
|
742 @subsection Distinguishing Kinds of Files
|
|
|
743
|
|
|
744 This section describes how to distinguish various kinds of files, such
|
|
|
745 as directories, symbolic links, and ordinary files.
|
|
|
746
|
|
|
747 @defun file-symlink-p filename
|
|
|
748 @cindex file symbolic links
|
|
|
749 If the file @var{filename} is a symbolic link, the @code{file-symlink-p}
|
|
|
750 function returns the file name to which it is linked. This may be the
|
|
|
751 name of a text file, a directory, or even another symbolic link, or it
|
|
|
752 may be a nonexistent file name.
|
|
|
753
|
|
|
754 If the file @var{filename} is not a symbolic link (or there is no such file),
|
|
444
|
755 @code{file-symlink-p} returns @code{nil}.
|
|
428
|
756
|
|
|
757 @example
|
|
|
758 @group
|
|
|
759 (file-symlink-p "foo")
|
|
|
760 @result{} nil
|
|
|
761 @end group
|
|
|
762 @group
|
|
|
763 (file-symlink-p "sym-link")
|
|
|
764 @result{} "foo"
|
|
|
765 @end group
|
|
|
766 @group
|
|
|
767 (file-symlink-p "sym-link2")
|
|
|
768 @result{} "sym-link"
|
|
|
769 @end group
|
|
|
770 @group
|
|
|
771 (file-symlink-p "/bin")
|
|
|
772 @result{} "/pub/bin"
|
|
|
773 @end group
|
|
|
774 @end example
|
|
|
775
|
|
|
776 @c !!! file-symlink-p: should show output of ls -l for comparison
|
|
|
777 @end defun
|
|
|
778
|
|
|
779 @defun file-directory-p filename
|
|
|
780 This function returns @code{t} if @var{filename} is the name of an
|
|
|
781 existing directory, @code{nil} otherwise.
|
|
|
782
|
|
|
783 @example
|
|
|
784 @group
|
|
|
785 (file-directory-p "~rms")
|
|
|
786 @result{} t
|
|
|
787 @end group
|
|
|
788 @group
|
|
|
789 (file-directory-p "~rms/lewis/files.texi")
|
|
|
790 @result{} nil
|
|
|
791 @end group
|
|
|
792 @group
|
|
|
793 (file-directory-p "~rms/lewis/no-such-file")
|
|
|
794 @result{} nil
|
|
|
795 @end group
|
|
|
796 @group
|
|
|
797 (file-directory-p "$HOME")
|
|
|
798 @result{} nil
|
|
|
799 @end group
|
|
|
800 @group
|
|
|
801 (file-directory-p
|
|
|
802 (substitute-in-file-name "$HOME"))
|
|
|
803 @result{} t
|
|
|
804 @end group
|
|
|
805 @end example
|
|
|
806 @end defun
|
|
|
807
|
|
|
808 @defun file-regular-p filename
|
|
|
809 This function returns @code{t} if the file @var{filename} exists and is
|
|
|
810 a regular file (not a directory, symbolic link, named pipe, terminal, or
|
|
|
811 other I/O device).
|
|
|
812 @end defun
|
|
|
813
|
|
|
814 @node Truenames
|
|
|
815 @subsection Truenames
|
|
|
816 @cindex truename (of file)
|
|
|
817
|
|
|
818 @c Emacs 19 features
|
|
|
819 The @dfn{truename} of a file is the name that you get by following
|
|
|
820 symbolic links until none remain, then expanding to get rid of @samp{.}
|
|
|
821 and @samp{..} as components. Strictly speaking, a file need not have a
|
|
|
822 unique truename; the number of distinct truenames a file has is equal to
|
|
|
823 the number of hard links to the file. However, truenames are useful
|
|
|
824 because they eliminate symbolic links as a cause of name variation.
|
|
|
825
|
|
|
826 @defun file-truename filename &optional default
|
|
|
827 The function @code{file-truename} returns the true name of the file
|
|
|
828 @var{filename}. This is the name that you get by following symbolic
|
|
|
829 links until none remain.
|
|
|
830
|
|
|
831 @c XEmacs allows relative filenames
|
|
|
832 If the filename is relative, @var{default} is the directory to start
|
|
|
833 with. If @var{default} is @code{nil} or missing, the current buffer's
|
|
|
834 value of @code{default-directory} is used.
|
|
|
835 @end defun
|
|
|
836
|
|
|
837 @xref{Buffer File Name}, for related information.
|
|
|
838
|
|
|
839 @node File Attributes
|
|
|
840 @subsection Other Information about Files
|
|
|
841
|
|
|
842 This section describes the functions for getting detailed information
|
|
|
843 about a file, other than its contents. This information includes the
|
|
|
844 mode bits that control access permission, the owner and group numbers,
|
|
|
845 the number of names, the inode number, the size, and the times of access
|
|
|
846 and modification.
|
|
|
847
|
|
|
848 @defun file-modes filename
|
|
|
849 @cindex permission
|
|
|
850 @cindex file attributes
|
|
|
851 This function returns the mode bits of @var{filename}, as an integer.
|
|
|
852 The mode bits are also called the file permissions, and they specify
|
|
|
853 access control in the usual Unix fashion. If the low-order bit is 1,
|
|
|
854 then the file is executable by all users, if the second-lowest-order bit
|
|
|
855 is 1, then the file is writable by all users, etc.
|
|
|
856
|
|
|
857 The highest value returnable is 4095 (7777 octal), meaning that
|
|
|
858 everyone has read, write, and execute permission, that the @sc{suid} bit
|
|
|
859 is set for both others and group, and that the sticky bit is set.
|
|
|
860
|
|
|
861 @example
|
|
|
862 @group
|
|
|
863 (file-modes "~/junk/diffs")
|
|
|
864 @result{} 492 ; @r{Decimal integer.}
|
|
|
865 @end group
|
|
|
866 @group
|
|
|
867 (format "%o" 492)
|
|
|
868 @result{} "754" ; @r{Convert to octal.}
|
|
|
869 @end group
|
|
|
870
|
|
|
871 @group
|
|
|
872 (set-file-modes "~/junk/diffs" 438)
|
|
|
873 @result{} nil
|
|
|
874 @end group
|
|
|
875
|
|
|
876 @group
|
|
|
877 (format "%o" 438)
|
|
|
878 @result{} "666" ; @r{Convert to octal.}
|
|
|
879 @end group
|
|
|
880
|
|
|
881 @group
|
|
|
882 % ls -l diffs
|
|
|
883 -rw-rw-rw- 1 lewis 0 3063 Oct 30 16:00 diffs
|
|
|
884 @end group
|
|
|
885 @end example
|
|
|
886 @end defun
|
|
|
887
|
|
|
888 @defun file-nlinks filename
|
|
|
889 This functions returns the number of names (i.e., hard links) that
|
|
|
890 file @var{filename} has. If the file does not exist, then this function
|
|
|
891 returns @code{nil}. Note that symbolic links have no effect on this
|
|
|
892 function, because they are not considered to be names of the files they
|
|
|
893 link to.
|
|
|
894
|
|
|
895 @example
|
|
|
896 @group
|
|
|
897 % ls -l foo*
|
|
|
898 -rw-rw-rw- 2 rms 4 Aug 19 01:27 foo
|
|
|
899 -rw-rw-rw- 2 rms 4 Aug 19 01:27 foo1
|
|
|
900 @end group
|
|
|
901
|
|
|
902 @group
|
|
|
903 (file-nlinks "foo")
|
|
|
904 @result{} 2
|
|
|
905 @end group
|
|
|
906 @group
|
|
|
907 (file-nlinks "doesnt-exist")
|
|
|
908 @result{} nil
|
|
|
909 @end group
|
|
|
910 @end example
|
|
|
911 @end defun
|
|
|
912
|
|
|
913 @defun file-attributes filename
|
|
|
914 This function returns a list of attributes of file @var{filename}. If
|
|
|
915 the specified file cannot be opened, it returns @code{nil}.
|
|
|
916
|
|
|
917 The elements of the list, in order, are:
|
|
|
918
|
|
|
919 @enumerate 0
|
|
|
920 @item
|
|
|
921 @code{t} for a directory, a string for a symbolic link (the name
|
|
|
922 linked to), or @code{nil} for a text file.
|
|
|
923
|
|
|
924 @c Wordy so as to prevent an overfull hbox. --rjc 15mar92
|
|
|
925 @item
|
|
|
926 The number of names the file has. Alternate names, also known as hard
|
|
|
927 links, can be created by using the @code{add-name-to-file} function
|
|
|
928 (@pxref{Changing File Attributes}).
|
|
|
929
|
|
|
930 @item
|
|
|
931 The file's @sc{uid}.
|
|
|
932
|
|
|
933 @item
|
|
|
934 The file's @sc{gid}.
|
|
|
935
|
|
|
936 @item
|
|
|
937 The time of last access, as a list of two integers.
|
|
|
938 The first integer has the high-order 16 bits of time,
|
|
|
939 the second has the low 16 bits. (This is similar to the
|
|
|
940 value of @code{current-time}; see @ref{Time of Day}.)
|
|
|
941
|
|
|
942 @item
|
|
|
943 The time of last modification as a list of two integers (as above).
|
|
|
944
|
|
|
945 @item
|
|
|
946 The time of last status change as a list of two integers (as above).
|
|
|
947
|
|
|
948 @item
|
|
|
949 The size of the file in bytes.
|
|
|
950
|
|
|
951 @item
|
|
|
952 The file's modes, as a string of ten letters or dashes,
|
|
|
953 as in @samp{ls -l}.
|
|
|
954
|
|
|
955 @item
|
|
|
956 @code{t} if the file's @sc{gid} would change if file were
|
|
|
957 deleted and recreated; @code{nil} otherwise.
|
|
|
958
|
|
|
959 @item
|
|
|
960 The file's inode number.
|
|
|
961
|
|
|
962 @item
|
|
|
963 The file system number of the file system that the file is in. This
|
|
|
964 element and the file's inode number together give enough information to
|
|
|
965 distinguish any two files on the system---no two files can have the same
|
|
|
966 values for both of these numbers.
|
|
|
967 @end enumerate
|
|
|
968
|
|
|
969 For example, here are the file attributes for @file{files.texi}:
|
|
|
970
|
|
|
971 @example
|
|
|
972 @group
|
|
|
973 (file-attributes "files.texi")
|
|
444
|
974 @result{} (nil
|
|
|
975 1
|
|
|
976 2235
|
|
|
977 75
|
|
|
978 (8489 20284)
|
|
|
979 (8489 20284)
|
|
428
|
980 (8489 20285)
|
|
444
|
981 14906
|
|
|
982 "-rw-rw-rw-"
|
|
|
983 nil
|
|
428
|
984 129500
|
|
|
985 -32252)
|
|
|
986 @end group
|
|
|
987 @end example
|
|
|
988
|
|
|
989 @noindent
|
|
|
990 and here is how the result is interpreted:
|
|
|
991
|
|
|
992 @table @code
|
|
|
993 @item nil
|
|
|
994 is neither a directory nor a symbolic link.
|
|
|
995
|
|
|
996 @item 1
|
|
|
997 has only one name (the name @file{files.texi} in the current default
|
|
|
998 directory).
|
|
|
999
|
|
|
1000 @item 2235
|
|
|
1001 is owned by the user with @sc{uid} 2235.
|
|
|
1002
|
|
|
1003 @item 75
|
|
|
1004 is in the group with @sc{gid} 75.
|
|
|
1005
|
|
|
1006 @item (8489 20284)
|
|
|
1007 was last accessed on Aug 19 00:09. Use @code{format-time-string} to
|
|
|
1008 ! convert this number into a time string. @xref{Time Conversion}.
|
|
|
1009
|
|
|
1010 @item (8489 20284)
|
|
|
1011 was last modified on Aug 19 00:09.
|
|
|
1012
|
|
|
1013 @item (8489 20285)
|
|
|
1014 last had its inode changed on Aug 19 00:09.
|
|
|
1015
|
|
|
1016 @item 14906
|
|
|
1017 is 14906 characters long.
|
|
|
1018
|
|
|
1019 @item "-rw-rw-rw-"
|
|
|
1020 has a mode of read and write access for the owner, group, and world.
|
|
|
1021
|
|
|
1022 @item nil
|
|
|
1023 would retain the same @sc{gid} if it were recreated.
|
|
|
1024
|
|
|
1025 @item 129500
|
|
|
1026 has an inode number of 129500.
|
|
|
1027 @item -32252
|
|
|
1028 is on file system number -32252.
|
|
|
1029 @end table
|
|
|
1030 @end defun
|
|
|
1031
|
|
|
1032 @node Changing File Attributes
|
|
|
1033 @section Changing File Names and Attributes
|
|
|
1034 @cindex renaming files
|
|
|
1035 @cindex copying files
|
|
|
1036 @cindex deleting files
|
|
|
1037 @cindex linking files
|
|
|
1038 @cindex setting modes of files
|
|
|
1039
|
|
|
1040 The functions in this section rename, copy, delete, link, and set the
|
|
|
1041 modes of files.
|
|
|
1042
|
|
444
|
1043 In the functions that have arguments @var{newname} and
|
|
|
1044 @var{ok-if-already-exists}, if a file by the name of @var{newname}
|
|
|
1045 already exists, the actions taken depend on the value of
|
|
|
1046 @var{ok-if-already-exists}:
|
|
428
|
1047
|
|
|
1048 @itemize @bullet
|
|
|
1049 @item
|
|
|
1050 Signal a @code{file-already-exists} error if
|
|
|
1051 @var{ok-if-already-exists} is @code{nil}.
|
|
|
1052
|
|
|
1053 @item
|
|
444
|
1054 Request confirmation if @var{ok-if-already-exists} is a number. This is
|
|
|
1055 what happens when the function is invoked interactively.
|
|
428
|
1056
|
|
|
1057 @item
|
|
|
1058 Replace the old file without confirmation if @var{ok-if-already-exists}
|
|
|
1059 is any other value.
|
|
|
1060 @end itemize
|
|
|
1061
|
|
444
|
1062 @deffn Command add-name-to-file filename newname &optional ok-if-already-exists
|
|
428
|
1063 @cindex file with multiple names
|
|
|
1064 @cindex file hard link
|
|
444
|
1065 This function gives the file named @var{filename} the additional name
|
|
428
|
1066 @var{newname}. This means that @var{newname} becomes a new ``hard
|
|
444
|
1067 link'' to @var{filename}. Both these arguments must be strings.
|
|
428
|
1068
|
|
|
1069 In the first part of the following example, we list two files,
|
|
|
1070 @file{foo} and @file{foo3}.
|
|
|
1071
|
|
|
1072 @example
|
|
|
1073 @group
|
|
|
1074 % ls -l fo*
|
|
|
1075 -rw-rw-rw- 1 rms 29 Aug 18 20:32 foo
|
|
|
1076 -rw-rw-rw- 1 rms 24 Aug 18 20:31 foo3
|
|
|
1077 @end group
|
|
|
1078 @end example
|
|
|
1079
|
|
|
1080 Then we evaluate the form @code{(add-name-to-file "~/lewis/foo"
|
|
|
1081 "~/lewis/foo2")}. Again we list the files. This shows two names,
|
|
|
1082 @file{foo} and @file{foo2}.
|
|
|
1083
|
|
|
1084 @example
|
|
|
1085 @group
|
|
|
1086 (add-name-to-file "~/lewis/foo1" "~/lewis/foo2")
|
|
|
1087 @result{} nil
|
|
|
1088 @end group
|
|
|
1089
|
|
|
1090 @group
|
|
|
1091 % ls -l fo*
|
|
|
1092 -rw-rw-rw- 2 rms 29 Aug 18 20:32 foo
|
|
|
1093 -rw-rw-rw- 2 rms 29 Aug 18 20:32 foo2
|
|
|
1094 -rw-rw-rw- 1 rms 24 Aug 18 20:31 foo3
|
|
|
1095 @end group
|
|
|
1096 @end example
|
|
|
1097
|
|
|
1098 @c !!! Check whether this set of examples is consistent. --rjc 15mar92
|
|
|
1099 Finally, we evaluate the following:
|
|
|
1100
|
|
|
1101 @example
|
|
|
1102 (add-name-to-file "~/lewis/foo" "~/lewis/foo3" t)
|
|
|
1103 @end example
|
|
|
1104
|
|
|
1105 @noindent
|
|
|
1106 and list the files again. Now there are three names
|
|
|
1107 for one file: @file{foo}, @file{foo2}, and @file{foo3}. The old
|
|
|
1108 contents of @file{foo3} are lost.
|
|
|
1109
|
|
|
1110 @example
|
|
|
1111 @group
|
|
|
1112 (add-name-to-file "~/lewis/foo1" "~/lewis/foo3")
|
|
|
1113 @result{} nil
|
|
|
1114 @end group
|
|
|
1115
|
|
|
1116 @group
|
|
|
1117 % ls -l fo*
|
|
|
1118 -rw-rw-rw- 3 rms 29 Aug 18 20:32 foo
|
|
|
1119 -rw-rw-rw- 3 rms 29 Aug 18 20:32 foo2
|
|
|
1120 -rw-rw-rw- 3 rms 29 Aug 18 20:32 foo3
|
|
|
1121 @end group
|
|
|
1122 @end example
|
|
|
1123
|
|
444
|
1124 This function is meaningless on non-Unix systems, where multiple names
|
|
|
1125 for one file are not allowed.
|
|
428
|
1126
|
|
|
1127 See also @code{file-nlinks} in @ref{File Attributes}.
|
|
|
1128 @end deffn
|
|
|
1129
|
|
|
1130 @deffn Command rename-file filename newname &optional ok-if-already-exists
|
|
|
1131 This command renames the file @var{filename} as @var{newname}.
|
|
|
1132
|
|
|
1133 If @var{filename} has additional names aside from @var{filename}, it
|
|
|
1134 continues to have those names. In fact, adding the name @var{newname}
|
|
|
1135 with @code{add-name-to-file} and then deleting @var{filename} has the
|
|
|
1136 same effect as renaming, aside from momentary intermediate states.
|
|
|
1137
|
|
|
1138 In an interactive call, this function prompts for @var{filename} and
|
|
|
1139 @var{newname} in the minibuffer; also, it requests confirmation if
|
|
|
1140 @var{newname} already exists.
|
|
|
1141 @end deffn
|
|
|
1142
|
|
444
|
1143 @deffn Command copy-file filename newname &optional ok-if-already-exists time
|
|
|
1144 This command copies the file @var{filename} to @var{newname}. An
|
|
|
1145 error is signaled if @var{filename} does not exist.
|
|
428
|
1146
|
|
|
1147 If @var{time} is non-@code{nil}, then this functions gives the new
|
|
|
1148 file the same last-modified time that the old one has. (This works on
|
|
|
1149 only some operating systems.)
|
|
|
1150
|
|
|
1151 In an interactive call, this function prompts for @var{filename} and
|
|
|
1152 @var{newname} in the minibuffer; also, it requests confirmation if
|
|
|
1153 @var{newname} already exists.
|
|
|
1154 @end deffn
|
|
|
1155
|
|
|
1156 @deffn Command delete-file filename
|
|
|
1157 @pindex rm
|
|
|
1158 This command deletes the file @var{filename}, like the shell command
|
|
|
1159 @samp{rm @var{filename}}. If the file has multiple names, it continues
|
|
|
1160 to exist under the other names.
|
|
|
1161
|
|
|
1162 A suitable kind of @code{file-error} error is signaled if the file
|
|
|
1163 does not exist, or is not deletable. (On Unix, a file is deletable if
|
|
|
1164 its directory is writable.)
|
|
|
1165
|
|
|
1166 See also @code{delete-directory} in @ref{Create/Delete Dirs}.
|
|
|
1167 @end deffn
|
|
|
1168
|
|
444
|
1169 @deffn Command make-symbolic-link filename newname &optional ok-if-already-exists
|
|
428
|
1170 @pindex ln
|
|
|
1171 @kindex file-already-exists
|
|
|
1172 This command makes a symbolic link to @var{filename}, named
|
|
|
1173 @var{newname}. This is like the shell command @samp{ln -s
|
|
|
1174 @var{filename} @var{newname}}.
|
|
|
1175
|
|
|
1176 In an interactive call, this function prompts for @var{filename} and
|
|
|
1177 @var{newname} in the minibuffer; also, it requests confirmation if
|
|
|
1178 @var{newname} already exists.
|
|
|
1179 @end deffn
|
|
|
1180
|
|
|
1181 @defun set-file-modes filename mode
|
|
|
1182 This function sets mode bits of @var{filename} to @var{mode} (which must
|
|
|
1183 be an integer). Only the low 12 bits of @var{mode} are used.
|
|
|
1184 @end defun
|
|
|
1185
|
|
|
1186 @c Emacs 19 feature
|
|
|
1187 @defun set-default-file-modes mode
|
|
|
1188 This function sets the default file protection for new files created by
|
|
|
1189 XEmacs and its subprocesses. Every file created with XEmacs initially has
|
|
|
1190 this protection. On Unix, the default protection is the bitwise
|
|
|
1191 complement of the ``umask'' value.
|
|
|
1192
|
|
|
1193 The argument @var{mode} must be an integer. Only the low 9 bits of
|
|
|
1194 @var{mode} are used.
|
|
|
1195
|
|
|
1196 Saving a modified version of an existing file does not count as creating
|
|
|
1197 the file; it does not change the file's mode, and does not use the
|
|
|
1198 default file protection.
|
|
|
1199 @end defun
|
|
|
1200
|
|
|
1201 @defun default-file-modes
|
|
|
1202 This function returns the current default protection value.
|
|
|
1203 @end defun
|
|
|
1204
|
|
|
1205 @cindex MS-DOS and file modes
|
|
|
1206 @cindex file modes and MS-DOS
|
|
|
1207 On MS-DOS, there is no such thing as an ``executable'' file mode bit.
|
|
|
1208 So Emacs considers a file executable if its name ends in @samp{.com},
|
|
|
1209 @samp{.bat} or @samp{.exe}. This is reflected in the values returned
|
|
|
1210 by @code{file-modes} and @code{file-attributes}.
|
|
|
1211
|
|
|
1212 @node File Names
|
|
|
1213 @section File Names
|
|
|
1214 @cindex file names
|
|
|
1215
|
|
|
1216 Files are generally referred to by their names, in XEmacs as elsewhere.
|
|
|
1217 File names in XEmacs are represented as strings. The functions that
|
|
|
1218 operate on a file all expect a file name argument.
|
|
|
1219
|
|
|
1220 In addition to operating on files themselves, XEmacs Lisp programs
|
|
|
1221 often need to operate on the names; i.e., to take them apart and to use
|
|
|
1222 part of a name to construct related file names. This section describes
|
|
|
1223 how to manipulate file names.
|
|
|
1224
|
|
|
1225 The functions in this section do not actually access files, so they
|
|
|
1226 can operate on file names that do not refer to an existing file or
|
|
|
1227 directory.
|
|
|
1228
|
|
444
|
1229 On MS-DOS, these functions understand MS-DOS file-name syntax as well as
|
|
|
1230 Unix syntax. This is so that all the standard Lisp libraries can specify
|
|
|
1231 file names in Unix syntax and work properly on all systems without
|
|
|
1232 change. Similarly for other operating systems.
|
|
428
|
1233
|
|
|
1234 @menu
|
|
|
1235 * File Name Components:: The directory part of a file name, and the rest.
|
|
|
1236 * Directory Names:: A directory's name as a directory
|
|
|
1237 is different from its name as a file.
|
|
|
1238 * Relative File Names:: Some file names are relative to a current directory.
|
|
|
1239 * File Name Expansion:: Converting relative file names to absolute ones.
|
|
|
1240 * Unique File Names:: Generating names for temporary files.
|
|
|
1241 * File Name Completion:: Finding the completions for a given file name.
|
|
|
1242 * User Name Completion:: Finding the completions for a given user name.
|
|
|
1243 @end menu
|
|
|
1244
|
|
|
1245 @node File Name Components
|
|
|
1246 @subsection File Name Components
|
|
|
1247 @cindex directory part (of file name)
|
|
|
1248 @cindex nondirectory part (of file name)
|
|
|
1249 @cindex version number (in file name)
|
|
|
1250
|
|
|
1251 The operating system groups files into directories. To specify a
|
|
|
1252 file, you must specify the directory and the file's name within that
|
|
|
1253 directory. Therefore, XEmacs considers a file name as having two main
|
|
|
1254 parts: the @dfn{directory name} part, and the @dfn{nondirectory} part
|
|
|
1255 (or @dfn{file name within the directory}). Either part may be empty.
|
|
|
1256 Concatenating these two parts reproduces the original file name.
|
|
|
1257
|
|
|
1258 On Unix, the directory part is everything up to and including the last
|
|
444
|
1259 slash; the nondirectory part is the rest.
|
|
428
|
1260
|
|
|
1261 For some purposes, the nondirectory part is further subdivided into
|
|
|
1262 the name proper and the @dfn{version number}. On Unix, only backup
|
|
444
|
1263 files have version numbers in their names.
|
|
428
|
1264
|
|
|
1265 @defun file-name-directory filename
|
|
|
1266 This function returns the directory part of @var{filename} (or
|
|
|
1267 @code{nil} if @var{filename} does not include a directory part). On
|
|
444
|
1268 Unix, the function returns a string ending in a slash.
|
|
428
|
1269
|
|
|
1270 @example
|
|
|
1271 @group
|
|
|
1272 (file-name-directory "lewis/foo") ; @r{Unix example}
|
|
|
1273 @result{} "lewis/"
|
|
|
1274 @end group
|
|
|
1275 @group
|
|
|
1276 (file-name-directory "foo") ; @r{Unix example}
|
|
|
1277 @result{} nil
|
|
|
1278 @end group
|
|
|
1279 @end example
|
|
|
1280 @end defun
|
|
|
1281
|
|
|
1282 @defun file-name-nondirectory filename
|
|
|
1283 This function returns the nondirectory part of @var{filename}.
|
|
|
1284
|
|
|
1285 @example
|
|
|
1286 @group
|
|
|
1287 (file-name-nondirectory "lewis/foo")
|
|
|
1288 @result{} "foo"
|
|
|
1289 @end group
|
|
|
1290 @group
|
|
|
1291 (file-name-nondirectory "foo")
|
|
|
1292 @result{} "foo"
|
|
|
1293 @end group
|
|
|
1294 @end example
|
|
|
1295 @end defun
|
|
|
1296
|
|
|
1297 @defun file-name-sans-versions filename &optional keep-backup-version
|
|
|
1298 This function returns @var{filename} without any file version numbers,
|
|
|
1299 backup version numbers, or trailing tildes.
|
|
|
1300
|
|
|
1301 @c XEmacs feature?
|
|
|
1302 If @var{keep-backup-version} is non-@code{nil}, we do not remove backup
|
|
|
1303 version numbers, only true file version numbers.
|
|
|
1304
|
|
|
1305 @example
|
|
|
1306 @group
|
|
|
1307 (file-name-sans-versions "~rms/foo.~1~")
|
|
|
1308 @result{} "~rms/foo"
|
|
|
1309 @end group
|
|
|
1310 @group
|
|
|
1311 (file-name-sans-versions "~rms/foo~")
|
|
|
1312 @result{} "~rms/foo"
|
|
|
1313 @end group
|
|
|
1314 @group
|
|
|
1315 (file-name-sans-versions "~rms/foo")
|
|
|
1316 @result{} "~rms/foo"
|
|
|
1317 @end group
|
|
|
1318 @end example
|
|
|
1319 @end defun
|
|
|
1320
|
|
|
1321 @defun file-name-sans-extension filename
|
|
|
1322 This function returns @var{filename} minus its ``extension,'' if any.
|
|
|
1323 The extension, in a file name, is the part that starts with the last
|
|
|
1324 @samp{.} in the last name component. For example,
|
|
|
1325
|
|
|
1326 @example
|
|
|
1327 (file-name-sans-extension "foo.lose.c")
|
|
|
1328 @result{} "foo.lose"
|
|
|
1329 (file-name-sans-extension "big.hack/foo")
|
|
|
1330 @result{} "big.hack/foo"
|
|
|
1331 @end example
|
|
|
1332 @end defun
|
|
|
1333
|
|
|
1334 @node Directory Names
|
|
|
1335 @subsection Directory Names
|
|
|
1336 @cindex directory name
|
|
|
1337 @cindex file name of directory
|
|
|
1338
|
|
|
1339 A @dfn{directory name} is the name of a directory. A directory is a
|
|
|
1340 kind of file, and it has a file name, which is related to the directory
|
|
|
1341 name but not identical to it. (This is not quite the same as the usual
|
|
|
1342 Unix terminology.) These two different names for the same entity are
|
|
|
1343 related by a syntactic transformation. On Unix, this is simple: a
|
|
|
1344 directory name ends in a slash, whereas the directory's name as a file
|
|
444
|
1345 lacks that slash.
|
|
428
|
1346
|
|
|
1347 The difference between a directory name and its name as a file is
|
|
|
1348 subtle but crucial. When an XEmacs variable or function argument is
|
|
|
1349 described as being a directory name, a file name of a directory is not
|
|
|
1350 acceptable.
|
|
|
1351
|
|
|
1352 The following two functions convert between directory names and file
|
|
|
1353 names. They do nothing special with environment variable substitutions
|
|
|
1354 such as @samp{$HOME}, and the constructs @samp{~}, and @samp{..}.
|
|
|
1355
|
|
|
1356 @defun file-name-as-directory filename
|
|
|
1357 This function returns a string representing @var{filename} in a form
|
|
|
1358 that the operating system will interpret as the name of a directory. In
|
|
444
|
1359 Unix, this means appending a slash to the string.
|
|
428
|
1360
|
|
|
1361 @example
|
|
|
1362 @group
|
|
|
1363 (file-name-as-directory "~rms/lewis")
|
|
|
1364 @result{} "~rms/lewis/"
|
|
|
1365 @end group
|
|
|
1366 @end example
|
|
|
1367 @end defun
|
|
|
1368
|
|
|
1369 @defun directory-file-name dirname
|
|
|
1370 This function returns a string representing @var{dirname} in a form
|
|
|
1371 that the operating system will interpret as the name of a file. On
|
|
444
|
1372 Unix, this means removing a final slash from the string.
|
|
428
|
1373
|
|
|
1374 @example
|
|
|
1375 @group
|
|
|
1376 (directory-file-name "~lewis/")
|
|
|
1377 @result{} "~lewis"
|
|
|
1378 @end group
|
|
|
1379 @end example
|
|
|
1380 @end defun
|
|
|
1381
|
|
|
1382 @cindex directory name abbreviation
|
|
|
1383 Directory name abbreviations are useful for directories that are
|
|
|
1384 normally accessed through symbolic links. Sometimes the users recognize
|
|
|
1385 primarily the link's name as ``the name'' of the directory, and find it
|
|
|
1386 annoying to see the directory's ``real'' name. If you define the link
|
|
|
1387 name as an abbreviation for the ``real'' name, XEmacs shows users the
|
|
|
1388 abbreviation instead.
|
|
|
1389
|
|
|
1390 If you wish to convert a directory name to its abbreviation, use this
|
|
|
1391 function:
|
|
|
1392
|
|
444
|
1393 @defun abbreviate-file-name filename &optional hack-homedir
|
|
428
|
1394 This function applies abbreviations from @code{directory-abbrev-alist}
|
|
|
1395 to its argument, and substitutes @samp{~} for the user's home
|
|
|
1396 directory.
|
|
|
1397
|
|
|
1398 @c XEmacs feature?
|
|
|
1399 If @var{hack-homedir} is non-@code{nil}, then this also substitutes
|
|
|
1400 @samp{~} for the user's home directory.
|
|
|
1401
|
|
|
1402 @end defun
|
|
|
1403
|
|
|
1404 @defvar directory-abbrev-alist
|
|
|
1405 The variable @code{directory-abbrev-alist} contains an alist of
|
|
|
1406 abbreviations to use for file directories. Each element has the form
|
|
|
1407 @code{(@var{from} . @var{to})}, and says to replace @var{from} with
|
|
|
1408 @var{to} when it appears in a directory name. The @var{from} string is
|
|
|
1409 actually a regular expression; it should always start with @samp{^}.
|
|
|
1410 The function @code{abbreviate-file-name} performs these substitutions.
|
|
|
1411
|
|
|
1412 You can set this variable in @file{site-init.el} to describe the
|
|
|
1413 abbreviations appropriate for your site.
|
|
|
1414
|
|
|
1415 Here's an example, from a system on which file system @file{/home/fsf}
|
|
|
1416 and so on are normally accessed through symbolic links named @file{/fsf}
|
|
|
1417 and so on.
|
|
|
1418
|
|
|
1419 @example
|
|
|
1420 (("^/home/fsf" . "/fsf")
|
|
|
1421 ("^/home/gp" . "/gp")
|
|
|
1422 ("^/home/gd" . "/gd"))
|
|
|
1423 @end example
|
|
|
1424 @end defvar
|
|
|
1425
|
|
|
1426 @c To convert a directory name to its abbreviation, use this
|
|
|
1427 @c function:
|
|
|
1428 @c
|
|
|
1429 @c @defun abbreviate-file-name dirname
|
|
|
1430 @c This function applies abbreviations from @code{directory-abbrev-alist}
|
|
|
1431 @c to its argument, and substitutes @samp{~} for the user's home
|
|
|
1432 @c directory.
|
|
|
1433 @c @end defun
|
|
|
1434
|
|
|
1435 @node Relative File Names
|
|
|
1436 @subsection Absolute and Relative File Names
|
|
|
1437 @cindex absolute file name
|
|
|
1438 @cindex relative file name
|
|
|
1439
|
|
|
1440 All the directories in the file system form a tree starting at the
|
|
|
1441 root directory. A file name can specify all the directory names
|
|
|
1442 starting from the root of the tree; then it is called an @dfn{absolute}
|
|
|
1443 file name. Or it can specify the position of the file in the tree
|
|
|
1444 relative to a default directory; then it is called a @dfn{relative}
|
|
|
1445 file name. On Unix, an absolute file name starts with a slash or a
|
|
444
|
1446 tilde (@samp{~}), and a relative one does not.
|
|
428
|
1447
|
|
|
1448 @defun file-name-absolute-p filename
|
|
|
1449 This function returns @code{t} if file @var{filename} is an absolute
|
|
444
|
1450 file name, @code{nil} otherwise.
|
|
428
|
1451
|
|
|
1452 @example
|
|
|
1453 @group
|
|
|
1454 (file-name-absolute-p "~rms/foo")
|
|
|
1455 @result{} t
|
|
|
1456 @end group
|
|
|
1457 @group
|
|
|
1458 (file-name-absolute-p "rms/foo")
|
|
|
1459 @result{} nil
|
|
|
1460 @end group
|
|
|
1461 @group
|
|
|
1462 (file-name-absolute-p "/user/rms/foo")
|
|
|
1463 @result{} t
|
|
|
1464 @end group
|
|
|
1465 @end example
|
|
|
1466 @end defun
|
|
|
1467
|
|
|
1468 @node File Name Expansion
|
|
|
1469 @subsection Functions that Expand Filenames
|
|
|
1470 @cindex expansion of file names
|
|
|
1471
|
|
|
1472 @dfn{Expansion} of a file name means converting a relative file name
|
|
|
1473 to an absolute one. Since this is done relative to a default directory,
|
|
|
1474 you must specify the default directory name as well as the file name to
|
|
|
1475 be expanded. Expansion also simplifies file names by eliminating
|
|
|
1476 redundancies such as @file{./} and @file{@var{name}/../}.
|
|
|
1477
|
|
|
1478 @defun expand-file-name filename &optional directory
|
|
|
1479 This function converts @var{filename} to an absolute file name. If
|
|
|
1480 @var{directory} is supplied, it is the directory to start with if
|
|
|
1481 @var{filename} is relative. (The value of @var{directory} should itself
|
|
|
1482 be an absolute directory name; it may start with @samp{~}.)
|
|
|
1483 Otherwise, the current buffer's value of @code{default-directory} is
|
|
|
1484 used. For example:
|
|
|
1485
|
|
|
1486 @example
|
|
|
1487 @group
|
|
|
1488 (expand-file-name "foo")
|
|
|
1489 @result{} "/xcssun/users/rms/lewis/foo"
|
|
|
1490 @end group
|
|
|
1491 @group
|
|
|
1492 (expand-file-name "../foo")
|
|
|
1493 @result{} "/xcssun/users/rms/foo"
|
|
|
1494 @end group
|
|
|
1495 @group
|
|
|
1496 (expand-file-name "foo" "/usr/spool/")
|
|
|
1497 @result{} "/usr/spool/foo"
|
|
|
1498 @end group
|
|
|
1499 @group
|
|
|
1500 (expand-file-name "$HOME/foo")
|
|
|
1501 @result{} "/xcssun/users/rms/lewis/$HOME/foo"
|
|
|
1502 @end group
|
|
|
1503 @end example
|
|
|
1504
|
|
|
1505 Filenames containing @samp{.} or @samp{..} are simplified to their
|
|
|
1506 canonical form:
|
|
|
1507
|
|
|
1508 @example
|
|
|
1509 @group
|
|
|
1510 (expand-file-name "bar/../foo")
|
|
|
1511 @result{} "/xcssun/users/rms/lewis/foo"
|
|
|
1512 @end group
|
|
|
1513 @end example
|
|
|
1514
|
|
|
1515 @samp{~/} at the beginning is expanded into the user's home directory.
|
|
|
1516 A @samp{/} or @samp{~} following a @samp{/}.
|
|
|
1517
|
|
|
1518 Note that @code{expand-file-name} does @emph{not} expand environment
|
|
|
1519 variables; only @code{substitute-in-file-name} does that.
|
|
|
1520 @end defun
|
|
|
1521
|
|
|
1522 @c Emacs 19 feature
|
|
|
1523 @defun file-relative-name filename &optional directory
|
|
|
1524 This function does the inverse of expansion---it tries to return a
|
|
|
1525 relative name that is equivalent to @var{filename} when interpreted
|
|
|
1526 relative to @var{directory}.
|
|
|
1527
|
|
|
1528 @c XEmacs feature?
|
|
|
1529 If @var{directory} is @code{nil} or omitted, the value of
|
|
|
1530 @code{default-directory} is used.
|
|
|
1531
|
|
|
1532 @example
|
|
|
1533 (file-relative-name "/foo/bar" "/foo/")
|
|
|
1534 @result{} "bar")
|
|
|
1535 (file-relative-name "/foo/bar" "/hack/")
|
|
|
1536 @result{} "../foo/bar")
|
|
|
1537 @end example
|
|
|
1538 @end defun
|
|
|
1539
|
|
|
1540 @defvar default-directory
|
|
|
1541 The value of this buffer-local variable is the default directory for the
|
|
|
1542 current buffer. It should be an absolute directory name; it may start
|
|
|
1543 with @samp{~}. This variable is local in every buffer.
|
|
|
1544
|
|
|
1545 @code{expand-file-name} uses the default directory when its second
|
|
|
1546 argument is @code{nil}.
|
|
|
1547
|
|
|
1548 On Unix systems, the value is always a string ending with a slash.
|
|
|
1549
|
|
|
1550 @example
|
|
|
1551 @group
|
|
|
1552 default-directory
|
|
|
1553 @result{} "/user/lewis/manual/"
|
|
|
1554 @end group
|
|
|
1555 @end example
|
|
|
1556 @end defvar
|
|
|
1557
|
|
|
1558 @defun substitute-in-file-name filename
|
|
|
1559 This function replaces environment variable references in
|
|
|
1560 @var{filename} with the environment variable values. Following standard
|
|
|
1561 Unix shell syntax, @samp{$} is the prefix to substitute an environment
|
|
|
1562 variable value.
|
|
|
1563
|
|
|
1564 The environment variable name is the series of alphanumeric characters
|
|
|
1565 (including underscores) that follow the @samp{$}. If the character following
|
|
|
1566 the @samp{$} is a @samp{@{}, then the variable name is everything up to the
|
|
|
1567 matching @samp{@}}.
|
|
|
1568
|
|
|
1569 @c Wordy to avoid overfull hbox. --rjc 15mar92
|
|
|
1570 Here we assume that the environment variable @code{HOME}, which holds
|
|
|
1571 the user's home directory name, has value @samp{/xcssun/users/rms}.
|
|
|
1572
|
|
|
1573 @example
|
|
|
1574 @group
|
|
|
1575 (substitute-in-file-name "$HOME/foo")
|
|
|
1576 @result{} "/xcssun/users/rms/foo"
|
|
|
1577 @end group
|
|
|
1578 @end example
|
|
|
1579
|
|
|
1580 @c If a @samp{~} or a @samp{/} appears following a @samp{/}, after
|
|
|
1581 @c substitution, everything before the following @samp{/} is discarded:
|
|
|
1582
|
|
|
1583 After substitution, a @samp{/} or @samp{~} following a @samp{/} is taken
|
|
|
1584 to be the start of an absolute file name that overrides what precedes
|
|
|
1585 it, so everything before that @samp{/} or @samp{~} is deleted. For
|
|
|
1586 example:
|
|
|
1587
|
|
|
1588 @example
|
|
|
1589 @group
|
|
|
1590 (substitute-in-file-name "bar/~/foo")
|
|
|
1591 @result{} "~/foo"
|
|
|
1592 @end group
|
|
|
1593 @group
|
|
|
1594 (substitute-in-file-name "/usr/local/$HOME/foo")
|
|
|
1595 @result{} "/xcssun/users/rms/foo"
|
|
|
1596 @end group
|
|
|
1597 @end example
|
|
|
1598 @end defun
|
|
|
1599
|
|
|
1600 @node Unique File Names
|
|
|
1601 @subsection Generating Unique File Names
|
|
|
1602
|
|
|
1603 Some programs need to write temporary files. Here is the usual way to
|
|
|
1604 construct a name for such a file:
|
|
|
1605
|
|
|
1606 @example
|
|
|
1607 (make-temp-name (expand-file-name @var{name-of-application} (temp-directory)))
|
|
|
1608 @end example
|
|
|
1609
|
|
|
1610 @noindent
|
|
|
1611 Here we use @code{(temp-directory)} to specify a directory for temporary
|
|
|
1612 files---under Unix, it will normally evaluate to @file{"/tmp/"}. The
|
|
|
1613 job of @code{make-temp-name} is to prevent two different users or two
|
|
|
1614 different processes from trying to use the same name.
|
|
|
1615
|
|
|
1616 @defun temp-directory
|
|
|
1617 This function returns the name of the directory to use for temporary
|
|
|
1618 files. Under Unix, this will be the value of @code{TMPDIR}, defaulting
|
|
|
1619 to @file{/tmp}. On Windows, this will be obtained from the @code{TEMP}
|
|
|
1620 or @code{TMP} environment variables, defaulting to @file{/}.
|
|
|
1621
|
|
|
1622 Note that the @code{temp-directory} function does not exist under FSF
|
|
|
1623 Emacs.
|
|
|
1624 @end defun
|
|
|
1625
|
|
|
1626 @defun make-temp-name prefix
|
|
|
1627 This function generates a temporary file name starting with
|
|
|
1628 @var{prefix}. The Emacs process number forms part of the result, so
|
|
|
1629 there is no danger of generating a name being used by another process.
|
|
|
1630
|
|
|
1631 @example
|
|
|
1632 @group
|
|
|
1633 (make-temp-name "/tmp/foo")
|
|
|
1634 @result{} "/tmp/fooGaAQjC"
|
|
|
1635 @end group
|
|
|
1636 @end example
|
|
|
1637
|
|
|
1638 In addition, this function makes an attempt to choose a name that does
|
|
444
|
1639 not specify an existing file. To make this work, @var{prefix} should be
|
|
428
|
1640 an absolute file name.
|
|
|
1641
|
|
|
1642 To avoid confusion, each Lisp application should preferably use a unique
|
|
|
1643 @var{prefix} to @code{make-temp-name}.
|
|
|
1644 @end defun
|
|
|
1645
|
|
|
1646 @node File Name Completion
|
|
|
1647 @subsection File Name Completion
|
|
|
1648 @cindex file name completion subroutines
|
|
|
1649 @cindex completion, file name
|
|
|
1650
|
|
|
1651 This section describes low-level subroutines for completing a file
|
|
|
1652 name. For other completion functions, see @ref{Completion}.
|
|
|
1653
|
|
|
1654 @defun file-name-all-completions partial-filename directory
|
|
444
|
1655 This function returns a list of all possible completions for files
|
|
428
|
1656 whose name starts with @var{partial-filename} in directory
|
|
|
1657 @var{directory}. The order of the completions is the order of the files
|
|
|
1658 in the directory, which is unpredictable and conveys no useful
|
|
|
1659 information.
|
|
|
1660
|
|
|
1661 The argument @var{partial-filename} must be a file name containing no
|
|
|
1662 directory part and no slash. The current buffer's default directory is
|
|
|
1663 prepended to @var{directory}, if @var{directory} is not absolute.
|
|
|
1664
|
|
444
|
1665 File names which end with any member of @code{completion-ignored-extensions}
|
|
|
1666 are not considered as possible completions for @var{partial-filename} unless
|
|
|
1667 there is no other possible completion. @code{completion-ignored-extensions}
|
|
|
1668 is not applied to the names of directories.
|
|
|
1669
|
|
428
|
1670 In the following example, suppose that the current default directory,
|
|
|
1671 @file{~rms/lewis}, has five files whose names begin with @samp{f}:
|
|
|
1672 @file{foo}, @file{file~}, @file{file.c}, @file{file.c.~1~}, and
|
|
|
1673 @file{file.c.~2~}.@refill
|
|
|
1674
|
|
|
1675 @example
|
|
|
1676 @group
|
|
|
1677 (file-name-all-completions "f" "")
|
|
444
|
1678 @result{} ("foo" "file~" "file.c.~2~"
|
|
428
|
1679 "file.c.~1~" "file.c")
|
|
|
1680 @end group
|
|
|
1681
|
|
|
1682 @group
|
|
444
|
1683 (file-name-all-completions "fo" "")
|
|
428
|
1684 @result{} ("foo")
|
|
|
1685 @end group
|
|
|
1686 @end example
|
|
|
1687 @end defun
|
|
|
1688
|
|
444
|
1689 @defun file-name-completion partial-filename directory
|
|
|
1690 This function completes the file name @var{partial-filename} in directory
|
|
428
|
1691 @var{directory}. It returns the longest prefix common to all file names
|
|
444
|
1692 in directory @var{directory} that start with @var{partial-filename}.
|
|
428
|
1693
|
|
444
|
1694 If only one match exists and @var{partial-filename} matches it exactly, the
|
|
428
|
1695 function returns @code{t}. The function returns @code{nil} if directory
|
|
444
|
1696 @var{directory} contains no name starting with @var{partial-filename}.
|
|
|
1697
|
|
|
1698 File names which end with any member of @code{completion-ignored-extensions}
|
|
|
1699 are not considered as possible completions for @var{partial-filename} unless
|
|
|
1700 there is no other possible completion. @code{completion-ignored-extensions}
|
|
|
1701 is not applied to the names of directories.
|
|
428
|
1702
|
|
|
1703 In the following example, suppose that the current default directory
|
|
|
1704 has five files whose names begin with @samp{f}: @file{foo},
|
|
|
1705 @file{file~}, @file{file.c}, @file{file.c.~1~}, and
|
|
|
1706 @file{file.c.~2~}.@refill
|
|
|
1707
|
|
|
1708 @example
|
|
|
1709 @group
|
|
|
1710 (file-name-completion "fi" "")
|
|
|
1711 @result{} "file"
|
|
|
1712 @end group
|
|
|
1713
|
|
|
1714 @group
|
|
|
1715 (file-name-completion "file.c.~1" "")
|
|
|
1716 @result{} "file.c.~1~"
|
|
|
1717 @end group
|
|
|
1718
|
|
|
1719 @group
|
|
|
1720 (file-name-completion "file.c.~1~" "")
|
|
|
1721 @result{} t
|
|
|
1722 @end group
|
|
|
1723
|
|
|
1724 @group
|
|
|
1725 (file-name-completion "file.c.~3" "")
|
|
|
1726 @result{} nil
|
|
|
1727 @end group
|
|
|
1728 @end example
|
|
|
1729 @end defun
|
|
|
1730
|
|
|
1731 @defopt completion-ignored-extensions
|
|
|
1732 @code{file-name-completion} usually ignores file names that end in any
|
|
|
1733 string in this list. It does not ignore them when all the possible
|
|
|
1734 completions end in one of these suffixes or when a buffer showing all
|
|
|
1735 possible completions is displayed.@refill
|
|
|
1736
|
|
|
1737 A typical value might look like this:
|
|
|
1738
|
|
|
1739 @example
|
|
|
1740 @group
|
|
|
1741 completion-ignored-extensions
|
|
|
1742 @result{} (".o" ".elc" "~" ".dvi")
|
|
|
1743 @end group
|
|
|
1744 @end example
|
|
|
1745 @end defopt
|
|
|
1746
|
|
|
1747 @node User Name Completion
|
|
|
1748 @subsection User Name Completion
|
|
|
1749 @cindex user name completion subroutines
|
|
|
1750 @cindex completion, user name
|
|
|
1751
|
|
|
1752 This section describes low-level subroutines for completing a user
|
|
|
1753 name. For other completion functions, see @ref{Completion}.
|
|
|
1754
|
|
|
1755 @defun user-name-all-completions partial-username
|
|
444
|
1756 This function returns a list of all possible completions for a user name
|
|
|
1757 starting with @var{partial-username}. The order of the completions is
|
|
|
1758 unpredictable and conveys no useful information.
|
|
428
|
1759
|
|
444
|
1760 The argument @var{partial-username} must be a partial user name
|
|
428
|
1761 containing no tilde character and no slash.
|
|
|
1762 @end defun
|
|
|
1763
|
|
444
|
1764 @defun user-name-completion partial-username
|
|
|
1765 This function completes a user name from @var{partial-username}. It
|
|
|
1766 returns the longest prefix common to all user names that start with
|
|
|
1767 @var{partial-username}.
|
|
428
|
1768
|
|
444
|
1769 If only one match exists and @var{partial-username} matches it exactly,
|
|
|
1770 the function returns @code{t}. The function returns @code{nil} if no
|
|
|
1771 user name starting with @var{partial-username} exists.
|
|
428
|
1772 @end defun
|
|
|
1773
|
|
444
|
1774 @defun user-name-completion-1 partial-username
|
|
|
1775 This function completes the partial user name @var{partial-username},
|
|
|
1776 like @code{user-name-completion}, differing only in the return value.
|
|
428
|
1777 This function returns the cons of the completion returned by
|
|
|
1778 @code{user-name-completion}, and a boolean indicating whether that
|
|
|
1779 completion was unique.
|
|
|
1780 @end defun
|
|
|
1781
|
|
|
1782
|
|
|
1783 @node Contents of Directories
|
|
|
1784 @section Contents of Directories
|
|
|
1785 @cindex directory-oriented functions
|
|
|
1786 @cindex file names in directory
|
|
|
1787
|
|
|
1788 A directory is a kind of file that contains other files entered under
|
|
|
1789 various names. Directories are a feature of the file system.
|
|
|
1790
|
|
|
1791 XEmacs can list the names of the files in a directory as a Lisp list,
|
|
|
1792 or display the names in a buffer using the @code{ls} shell command. In
|
|
|
1793 the latter case, it can optionally display information about each file,
|
|
|
1794 depending on the value of switches passed to the @code{ls} command.
|
|
|
1795
|
|
|
1796 @defun directory-files directory &optional full-name match-regexp nosort files-only
|
|
|
1797 This function returns a list of the names of the files in the directory
|
|
|
1798 @var{directory}. By default, the list is in alphabetical order.
|
|
|
1799
|
|
|
1800 If @var{full-name} is non-@code{nil}, the function returns the files'
|
|
|
1801 absolute file names. Otherwise, it returns just the names relative to
|
|
|
1802 the specified directory.
|
|
|
1803
|
|
|
1804 If @var{match-regexp} is non-@code{nil}, this function returns only
|
|
|
1805 those file names that contain that regular expression---the other file
|
|
|
1806 names are discarded from the list.
|
|
|
1807
|
|
|
1808 @c Emacs 19 feature
|
|
|
1809 If @var{nosort} is non-@code{nil}, @code{directory-files} does not sort
|
|
|
1810 the list, so you get the file names in no particular order. Use this if
|
|
|
1811 you want the utmost possible speed and don't care what order the files
|
|
|
1812 are processed in. If the order of processing is visible to the user,
|
|
|
1813 then the user will probably be happier if you do sort the names.
|
|
|
1814
|
|
|
1815 @c XEmacs feature
|
|
|
1816 If @var{files-only} is the symbol @code{t}, then only the ``files'' in
|
|
|
1817 the directory will be returned; subdirectories will be excluded. If
|
|
|
1818 @var{files-only} is not @code{nil} and not @code{t}, then only the
|
|
|
1819 subdirectories will be returned. Otherwise, if @var{files-only} is
|
|
|
1820 @code{nil} (the default) then both files and subdirectories will be
|
|
|
1821 returned.
|
|
|
1822
|
|
|
1823 @example
|
|
|
1824 @group
|
|
|
1825 (directory-files "~lewis")
|
|
|
1826 @result{} ("#foo#" "#foo.el#" "." ".."
|
|
444
|
1827 "dired-mods.el" "files.texi"
|
|
428
|
1828 "files.texi.~1~")
|
|
|
1829 @end group
|
|
|
1830 @end example
|
|
|
1831
|
|
|
1832 An error is signaled if @var{directory} is not the name of a directory
|
|
|
1833 that can be read.
|
|
|
1834 @end defun
|
|
|
1835
|
|
|
1836 @ignore @c Not in XEmacs
|
|
|
1837 @defun file-name-all-versions file dirname
|
|
|
1838 This function returns a list of all versions of the file named
|
|
|
1839 @var{file} in directory @var{dirname}.
|
|
|
1840 @end defun
|
|
|
1841 @end ignore
|
|
|
1842
|
|
|
1843 @defun insert-directory file switches &optional wildcard full-directory-p
|
|
|
1844 This function inserts (in the current buffer) a directory listing for
|
|
|
1845 directory @var{file}, formatted with @code{ls} according to
|
|
|
1846 @var{switches}. It leaves point after the inserted text.
|
|
|
1847
|
|
|
1848 The argument @var{file} may be either a directory name or a file
|
|
|
1849 specification including wildcard characters. If @var{wildcard} is
|
|
|
1850 non-@code{nil}, that means treat @var{file} as a file specification with
|
|
|
1851 wildcards.
|
|
|
1852
|
|
|
1853 If @var{full-directory-p} is non-@code{nil}, that means @var{file} is a
|
|
|
1854 directory and switches do not contain @samp{-d}, so that the listing
|
|
|
1855 should show the full contents of the directory. (The @samp{-d} option
|
|
|
1856 to @code{ls} says to describe a directory itself rather than its
|
|
|
1857 contents.)
|
|
|
1858
|
|
|
1859 This function works by running a directory listing program whose name is
|
|
|
1860 in the variable @code{insert-directory-program}. If @var{wildcard} is
|
|
|
1861 non-@code{nil}, it also runs the shell specified by
|
|
|
1862 @code{shell-file-name}, to expand the wildcards.
|
|
|
1863 @end defun
|
|
|
1864
|
|
|
1865 @defvar insert-directory-program
|
|
|
1866 This variable's value is the program to run to generate a directory listing
|
|
|
1867 for the function @code{insert-directory}.
|
|
|
1868 @end defvar
|
|
|
1869
|
|
|
1870 @node Create/Delete Dirs
|
|
|
1871 @section Creating and Deleting Directories
|
|
|
1872 @c Emacs 19 features
|
|
|
1873
|
|
|
1874 Most XEmacs Lisp file-manipulation functions get errors when used on
|
|
|
1875 files that are directories. For example, you cannot delete a directory
|
|
|
1876 with @code{delete-file}. These special functions exist to create and
|
|
|
1877 delete directories.
|
|
|
1878
|
|
|
1879 @deffn Command make-directory dirname &optional parents
|
|
|
1880 This function creates a directory named @var{dirname}. Interactively,
|
|
|
1881 the default choice of directory to create is the current default
|
|
|
1882 directory for file names. That is useful when you have visited a file
|
|
|
1883 in a nonexistent directory.
|
|
|
1884
|
|
|
1885 @c XEmacs feature
|
|
|
1886 Non-interactively, optional argument @var{parents} says whether to
|
|
|
1887 create parent directories if they don't exist. (Interactively, this
|
|
|
1888 always happens.)
|
|
|
1889 @end deffn
|
|
|
1890
|
|
|
1891 @deffn Command delete-directory dirname
|
|
|
1892 This function deletes the directory named @var{dirname}. The function
|
|
|
1893 @code{delete-file} does not work for files that are directories; you
|
|
|
1894 must use @code{delete-directory} in that case.
|
|
|
1895 @end deffn
|
|
|
1896
|
|
|
1897 @node Magic File Names
|
|
|
1898 @section Making Certain File Names ``Magic''
|
|
|
1899 @cindex magic file names
|
|
|
1900
|
|
|
1901 @c Emacs 19 feature
|
|
|
1902 You can implement special handling for certain file names. This is
|
|
|
1903 called making those names @dfn{magic}. You must supply a regular
|
|
|
1904 expression to define the class of names (all those that match the
|
|
|
1905 regular expression), plus a handler that implements all the primitive
|
|
|
1906 XEmacs file operations for file names that do match.
|
|
|
1907
|
|
|
1908 The variable @code{file-name-handler-alist} holds a list of handlers,
|
|
|
1909 together with regular expressions that determine when to apply each
|
|
|
1910 handler. Each element has this form:
|
|
|
1911
|
|
|
1912 @example
|
|
|
1913 (@var{regexp} . @var{handler})
|
|
|
1914 @end example
|
|
|
1915
|
|
|
1916 @noindent
|
|
|
1917 All the XEmacs primitives for file access and file name transformation
|
|
|
1918 check the given file name against @code{file-name-handler-alist}. If
|
|
|
1919 the file name matches @var{regexp}, the primitives handle that file by
|
|
|
1920 calling @var{handler}.
|
|
|
1921
|
|
|
1922 The first argument given to @var{handler} is the name of the primitive;
|
|
|
1923 the remaining arguments are the arguments that were passed to that
|
|
|
1924 operation. (The first of these arguments is typically the file name
|
|
|
1925 itself.) For example, if you do this:
|
|
|
1926
|
|
|
1927 @example
|
|
|
1928 (file-exists-p @var{filename})
|
|
|
1929 @end example
|
|
|
1930
|
|
|
1931 @noindent
|
|
|
1932 and @var{filename} has handler @var{handler}, then @var{handler} is
|
|
|
1933 called like this:
|
|
|
1934
|
|
|
1935 @example
|
|
|
1936 (funcall @var{handler} 'file-exists-p @var{filename})
|
|
|
1937 @end example
|
|
|
1938
|
|
|
1939 Here are the operations that a magic file name handler gets to handle:
|
|
|
1940
|
|
|
1941 @noindent
|
|
|
1942 @code{add-name-to-file}, @code{copy-file}, @code{delete-directory},
|
|
|
1943 @code{delete-file},@*
|
|
|
1944 @code{diff-latest-backup-file},
|
|
|
1945 @code{directory-file-name},
|
|
|
1946 @code{directory-files},
|
|
|
1947 @code{dired-compress-file}, @code{dired-uncache},
|
|
|
1948 @code{expand-file-name},@*
|
|
|
1949 @code{file-accessible-directory-p},
|
|
|
1950 @code{file-attributes}, @code{file-directory-p},
|
|
|
1951 @code{file-executable-p}, @code{file-exists-p}, @code{file-local-copy},
|
|
|
1952 @code{file-modes}, @code{file-name-all-completions},
|
|
|
1953 @code{file-name-as-directory}, @code{file-name-completion},
|
|
|
1954 @code{file-name-directory}, @code{file-name-nondirectory},
|
|
|
1955 @code{file-name-sans-versions}, @code{file-newer-than-file-p},
|
|
|
1956 @code{file-readable-p}, @code{file-regular-p}, @code{file-symlink-p},
|
|
|
1957 @code{file-truename}, @code{file-writable-p},
|
|
|
1958 @code{get-file-buffer},
|
|
|
1959 @code{insert-directory},
|
|
|
1960 @code{insert-file-contents}, @code{load}, @code{make-directory},
|
|
|
1961 @code{make-symbolic-link}, @code{rename-file}, @code{set-file-modes},
|
|
|
1962 @code{set-visited-file-modtime}, @code{unhandled-file-name-directory},
|
|
|
1963 @code{verify-visited-file-modtime}, @code{write-region}.
|
|
|
1964
|
|
|
1965 Handlers for @code{insert-file-contents} typically need to clear the
|
|
|
1966 buffer's modified flag, with @code{(set-buffer-modified-p nil)}, if the
|
|
|
1967 @var{visit} argument is non-@code{nil}. This also has the effect of
|
|
|
1968 unlocking the buffer if it is locked.
|
|
|
1969
|
|
|
1970 The handler function must handle all of the above operations, and
|
|
|
1971 possibly others to be added in the future. It need not implement all
|
|
|
1972 these operations itself---when it has nothing special to do for a
|
|
|
1973 certain operation, it can reinvoke the primitive, to handle the
|
|
|
1974 operation ``in the usual way''. It should always reinvoke the primitive
|
|
|
1975 for an operation it does not recognize. Here's one way to do this:
|
|
|
1976
|
|
|
1977 @smallexample
|
|
|
1978 (defun my-file-handler (operation &rest args)
|
|
|
1979 ;; @r{First check for the specific operations}
|
|
|
1980 ;; @r{that we have special handling for.}
|
|
|
1981 (cond ((eq operation 'insert-file-contents) @dots{})
|
|
|
1982 ((eq operation 'write-region) @dots{})
|
|
|
1983 @dots{}
|
|
|
1984 ;; @r{Handle any operation we don't know about.}
|
|
|
1985 (t (let ((inhibit-file-name-handlers
|
|
444
|
1986 (cons 'my-file-handler
|
|
428
|
1987 (and (eq inhibit-file-name-operation operation)
|
|
|
1988 inhibit-file-name-handlers)))
|
|
|
1989 (inhibit-file-name-operation operation))
|
|
|
1990 (apply operation args)))))
|
|
|
1991 @end smallexample
|
|
|
1992
|
|
|
1993 When a handler function decides to call the ordinary Emacs primitive for
|
|
|
1994 the operation at hand, it needs to prevent the primitive from calling
|
|
|
1995 the same handler once again, thus leading to an infinite recursion. The
|
|
|
1996 example above shows how to do this, with the variables
|
|
|
1997 @code{inhibit-file-name-handlers} and
|
|
|
1998 @code{inhibit-file-name-operation}. Be careful to use them exactly as
|
|
|
1999 shown above; the details are crucial for proper behavior in the case of
|
|
|
2000 multiple handlers, and for operations that have two file names that may
|
|
|
2001 each have handlers.
|
|
|
2002
|
|
|
2003 @defvar inhibit-file-name-handlers
|
|
|
2004 This variable holds a list of handlers whose use is presently inhibited
|
|
|
2005 for a certain operation.
|
|
|
2006 @end defvar
|
|
|
2007
|
|
|
2008 @defvar inhibit-file-name-operation
|
|
|
2009 The operation for which certain handlers are presently inhibited.
|
|
|
2010 @end defvar
|
|
|
2011
|
|
444
|
2012 @defun find-file-name-handler filename &optional operation
|
|
|
2013 This function returns the handler function for file name @var{filename}, or
|
|
428
|
2014 @code{nil} if there is none. The argument @var{operation} should be the
|
|
|
2015 operation to be performed on the file---the value you will pass to the
|
|
|
2016 handler as its first argument when you call it. The operation is needed
|
|
|
2017 for comparison with @code{inhibit-file-name-operation}.
|
|
|
2018 @end defun
|
|
|
2019
|
|
|
2020 @defun file-local-copy filename
|
|
|
2021 This function copies file @var{filename} to an ordinary non-magic file,
|
|
|
2022 if it isn't one already.
|
|
|
2023
|
|
|
2024 If @var{filename} specifies a ``magic'' file name, which programs
|
|
|
2025 outside Emacs cannot directly read or write, this copies the contents to
|
|
|
2026 an ordinary file and returns that file's name.
|
|
|
2027
|
|
|
2028 If @var{filename} is an ordinary file name, not magic, then this function
|
|
|
2029 does nothing and returns @code{nil}.
|
|
|
2030 @end defun
|
|
|
2031
|
|
|
2032 @defun unhandled-file-name-directory filename
|
|
|
2033 This function returns the name of a directory that is not magic.
|
|
|
2034 It uses the directory part of @var{filename} if that is not magic.
|
|
|
2035 Otherwise, it asks the handler what to do.
|
|
|
2036
|
|
|
2037 This is useful for running a subprocess; every subprocess must have a
|
|
|
2038 non-magic directory to serve as its current directory, and this function
|
|
|
2039 is a good way to come up with one.
|
|
|
2040 @end defun
|
|
|
2041
|
|
|
2042 @node Partial Files
|
|
|
2043 @section Partial Files
|
|
|
2044 @cindex partial files
|
|
|
2045
|
|
|
2046 @menu
|
|
|
2047 * Intro to Partial Files::
|
|
|
2048 * Creating a Partial File::
|
|
|
2049 * Detached Partial Files::
|
|
|
2050 @end menu
|
|
|
2051
|
|
|
2052 @node Intro to Partial Files
|
|
|
2053 @subsection Intro to Partial Files
|
|
|
2054
|
|
|
2055 A @dfn{partial file} is a section of a buffer (called the @dfn{master
|
|
|
2056 buffer}) that is placed in its own buffer and treated as its own file.
|
|
|
2057 Changes made to the partial file are not reflected in the master buffer
|
|
|
2058 until the partial file is ``saved'' using the standard buffer save
|
|
|
2059 commands. Partial files can be ``reverted'' (from the master buffer)
|
|
|
2060 just like normal files. When a file part is active on a master buffer,
|
|
|
2061 that section of the master buffer is marked as read-only. Two file
|
|
|
2062 parts on the same master buffer are not allowed to overlap. Partial
|
|
|
2063 file buffers are indicated by the words @samp{File Part} in the
|
|
|
2064 modeline.
|
|
|
2065
|
|
|
2066 The master buffer knows about all the partial files that are active on
|
|
|
2067 it, and thus killing or reverting the master buffer will be handled
|
|
|
2068 properly. When the master buffer is saved, if there are any unsaved
|
|
|
2069 partial files active on it then the user will be given the opportunity
|
|
|
2070 to first save these files.
|
|
|
2071
|
|
|
2072 When a partial file buffer is first modified, the master buffer is
|
|
|
2073 automatically marked as modified so that saving the master buffer will
|
|
|
2074 work correctly.
|
|
|
2075
|
|
|
2076 @node Creating a Partial File
|
|
|
2077 @subsection Creating a Partial File
|
|
|
2078
|
|
444
|
2079 @deffn Command make-file-part &optional start end name buffer
|
|
428
|
2080 Make a file part on buffer @var{buffer} out of the region. Call it
|
|
|
2081 @var{name}. This command creates a new buffer containing the contents
|
|
|
2082 of the region and marks the buffer as referring to the specified buffer,
|
|
|
2083 called the @dfn{master buffer}. When the file-part buffer is saved, its
|
|
|
2084 changes are integrated back into the master buffer. When the master
|
|
|
2085 buffer is deleted, all file parts are deleted with it.
|
|
|
2086
|
|
|
2087 When called from a function, expects four arguments, @var{start},
|
|
|
2088 @var{end}, @var{name}, and @var{buffer}, all of which are optional and
|
|
|
2089 default to the beginning of @var{buffer}, the end of @var{buffer}, a
|
|
444
|
2090 name generated from @var{buffer}'s name, and the current buffer,
|
|
428
|
2091 respectively.
|
|
444
|
2092 @end deffn
|
|
428
|
2093
|
|
|
2094 @node Detached Partial Files
|
|
|
2095 @subsection Detached Partial Files
|
|
|
2096
|
|
|
2097 Every partial file has an extent in the master buffer associated with it
|
|
|
2098 (called the @dfn{master extent}), marking where in the master buffer the
|
|
|
2099 partial file begins and ends. If the text in master buffer that is
|
|
|
2100 contained by the extent is deleted, then the extent becomes
|
|
|
2101 ``detached'', meaning that it no longer refers to a specific region of
|
|
|
2102 the master buffer. This can happen either when the text is deleted
|
|
|
2103 directly or when the master buffer is reverted. Neither of these should
|
|
|
2104 happen in normal usage because the master buffer should generally not be
|
|
|
2105 edited directly.
|
|
|
2106
|
|
|
2107 Before doing any operation that references a partial file's master
|
|
|
2108 extent, XEmacs checks to make sure that the extent is not detached. If
|
|
|
2109 this is the case, XEmacs warns the user of this and the master extent is
|
|
|
2110 deleted out of the master buffer, disconnecting the file part. The file
|
|
|
2111 part's filename is cleared and thus must be explicitly specified if the
|
|
|
2112 detached file part is to be saved.
|
|
|
2113
|
|
|
2114 @node Format Conversion
|
|
|
2115 @section File Format Conversion
|
|
|
2116
|
|
|
2117 @cindex file format conversion
|
|
|
2118 @cindex encoding file formats
|
|
|
2119 @cindex decoding file formats
|
|
|
2120 The variable @code{format-alist} defines a list of @dfn{file formats},
|
|
|
2121 which describe textual representations used in files for the data (text,
|
|
|
2122 text-properties, and possibly other information) in an Emacs buffer.
|
|
|
2123 Emacs performs format conversion if appropriate when reading and writing
|
|
|
2124 files.
|
|
|
2125
|
|
|
2126 @defvar format-alist
|
|
|
2127 This list contains one format definition for each defined file format.
|
|
|
2128 @end defvar
|
|
|
2129
|
|
|
2130 @cindex format definition
|
|
|
2131 Each format definition is a list of this form:
|
|
|
2132
|
|
|
2133 @example
|
|
|
2134 (@var{name} @var{doc-string} @var{regexp} @var{from-fn} @var{to-fn} @var{modify} @var{mode-fn})
|
|
|
2135 @end example
|
|
|
2136
|
|
|
2137 Here is what the elements in a format definition mean:
|
|
|
2138
|
|
|
2139 @table @var
|
|
|
2140 @item name
|
|
|
2141 The name of this format.
|
|
|
2142
|
|
|
2143 @item doc-string
|
|
|
2144 A documentation string for the format.
|
|
|
2145
|
|
|
2146 @item regexp
|
|
|
2147 A regular expression which is used to recognize files represented in
|
|
|
2148 this format.
|
|
|
2149
|
|
|
2150 @item from-fn
|
|
|
2151 A function to call to decode data in this format (to convert file data into
|
|
|
2152 the usual Emacs data representation).
|
|
|
2153
|
|
|
2154 The @var{from-fn} is called with two args, @var{begin} and @var{end},
|
|
|
2155 which specify the part of the buffer it should convert. It should convert
|
|
|
2156 the text by editing it in place. Since this can change the length of the
|
|
|
2157 text, @var{from-fn} should return the modified end position.
|
|
|
2158
|
|
|
2159 One responsibility of @var{from-fn} is to make sure that the beginning
|
|
|
2160 of the file no longer matches @var{regexp}. Otherwise it is likely to
|
|
|
2161 get called again.
|
|
|
2162
|
|
|
2163 @item to-fn
|
|
|
2164 A function to call to encode data in this format (to convert
|
|
|
2165 the usual Emacs data representation into this format).
|
|
|
2166
|
|
|
2167 The @var{to-fn} is called with two args, @var{begin} and @var{end},
|
|
|
2168 which specify the part of the buffer it should convert. There are
|
|
|
2169 two ways it can do the conversion:
|
|
|
2170
|
|
|
2171 @itemize @bullet
|
|
|
2172 @item
|
|
|
2173 By editing the buffer in place. In this case, @var{to-fn} should
|
|
|
2174 return the end-position of the range of text, as modified.
|
|
|
2175
|
|
|
2176 @item
|
|
|
2177 By returning a list of annotations. This is a list of elements of the
|
|
|
2178 form @code{(@var{position} . @var{string})}, where @var{position} is an
|
|
|
2179 integer specifying the relative position in the text to be written, and
|
|
|
2180 @var{string} is the annotation to add there. The list must be sorted in
|
|
|
2181 order of position when @var{to-fn} returns it.
|
|
|
2182
|
|
|
2183 When @code{write-region} actually writes the text from the buffer to the
|
|
|
2184 file, it intermixes the specified annotations at the corresponding
|
|
|
2185 positions. All this takes place without modifying the buffer.
|
|
|
2186 @end itemize
|
|
|
2187
|
|
|
2188 @item modify
|
|
|
2189 A flag, @code{t} if the encoding function modifies the buffer, and
|
|
|
2190 @code{nil} if it works by returning a list of annotations.
|
|
|
2191
|
|
|
2192 @item mode
|
|
|
2193 A mode function to call after visiting a file converted from this
|
|
|
2194 format.
|
|
|
2195 @end table
|
|
|
2196
|
|
|
2197 The function @code{insert-file-contents} automatically recognizes file
|
|
|
2198 formats when it reads the specified file. It checks the text of the
|
|
|
2199 beginning of the file against the regular expressions of the format
|
|
|
2200 definitions, and if it finds a match, it calls the decoding function for
|
|
|
2201 that format. Then it checks all the known formats over again.
|
|
|
2202 It keeps checking them until none of them is applicable.
|
|
|
2203
|
|
|
2204 Visiting a file, with @code{find-file-noselect} or the commands that use
|
|
|
2205 it, performs conversion likewise (because it calls
|
|
|
2206 @code{insert-file-contents}); it also calls the mode function for each
|
|
|
2207 format that it decodes. It stores a list of the format names in the
|
|
|
2208 buffer-local variable @code{buffer-file-format}.
|
|
|
2209
|
|
|
2210 @defvar buffer-file-format
|
|
|
2211 This variable states the format of the visited file. More precisely,
|
|
|
2212 this is a list of the file format names that were decoded in the course
|
|
|
2213 of visiting the current buffer's file. It is always local in all
|
|
|
2214 buffers.
|
|
|
2215 @end defvar
|
|
|
2216
|
|
|
2217 When @code{write-region} writes data into a file, it first calls the
|
|
|
2218 encoding functions for the formats listed in @code{buffer-file-format},
|
|
|
2219 in the order of appearance in the list.
|
|
|
2220
|
|
444
|
2221 @deffn Command format-write-file file format
|
|
428
|
2222 This command writes the current buffer contents into the file @var{file}
|
|
|
2223 in format @var{format}, and makes that format the default for future
|
|
|
2224 saves of the buffer. The argument @var{format} is a list of format
|
|
|
2225 names.
|
|
444
|
2226 @end deffn
|
|
428
|
2227
|
|
444
|
2228 @deffn Command format-find-file file format
|
|
428
|
2229 This command finds the file @var{file}, converting it according to
|
|
|
2230 format @var{format}. It also makes @var{format} the default if the
|
|
|
2231 buffer is saved later.
|
|
|
2232
|
|
|
2233 The argument @var{format} is a list of format names. If @var{format} is
|
|
|
2234 @code{nil}, no conversion takes place. Interactively, typing just
|
|
|
2235 @key{RET} for @var{format} specifies @code{nil}.
|
|
444
|
2236 @end deffn
|
|
428
|
2237
|
|
444
|
2238 @deffn Command format-insert-file file format &optional start end
|
|
428
|
2239 This command inserts the contents of file @var{file}, converting it
|
|
444
|
2240 according to format @var{format}. If @var{start} and @var{end} are
|
|
428
|
2241 non-@code{nil}, they specify which part of the file to read, as in
|
|
|
2242 @code{insert-file-contents} (@pxref{Reading from Files}).
|
|
|
2243
|
|
|
2244 The return value is like what @code{insert-file-contents} returns: a
|
|
|
2245 list of the absolute file name and the length of the data inserted
|
|
|
2246 (after conversion).
|
|
|
2247
|
|
|
2248 The argument @var{format} is a list of format names. If @var{format} is
|
|
|
2249 @code{nil}, no conversion takes place. Interactively, typing just
|
|
|
2250 @key{RET} for @var{format} specifies @code{nil}.
|
|
444
|
2251 @end deffn
|
|
428
|
2252
|
|
|
2253 @defvar auto-save-file-format
|
|
|
2254 This variable specifies the format to use for auto-saving. Its value is
|
|
|
2255 a list of format names, just like the value of
|
|
|
2256 @code{buffer-file-format}; but it is used instead of
|
|
|
2257 @code{buffer-file-format} for writing auto-save files. This variable
|
|
|
2258 is always local in all buffers.
|
|
|
2259 @end defvar
|
|
|
2260
|
|
|
2261 @node Files and MS-DOS
|
|
|
2262 @section Files and MS-DOS
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2263 @cindex MS-DOS file types
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2264 @cindex file types on MS-DOS
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2265 @cindex text files and binary files
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2266 @cindex binary files and text files
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2267
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2268 Emacs on MS-DOS makes a distinction between text files and binary
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2269 files. This is necessary because ordinary text files on MS-DOS use a
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2270 two character sequence between lines: carriage-return and linefeed
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2271 (@sc{crlf}). Emacs expects just a newline character (a linefeed) between
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2272 lines. When Emacs reads or writes a text file on MS-DOS, it needs to
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2273 convert the line separators. This means it needs to know which files
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2274 are text files and which are binary. It makes this decision when
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2275 visiting a file, and records the decision in the variable
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2276 @code{buffer-file-type} for use when the file is saved.
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2277
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2278 @xref{MS-DOS Subprocesses}, for a related feature for subprocesses.
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2279
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2280 @defvar buffer-file-type
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2281 This variable, automatically local in each buffer, records the file type
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2282 of the buffer's visited file. The value is @code{nil} for text,
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2283 @code{t} for binary.
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2284 @end defvar
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2285
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2286 @defun find-buffer-file-type filename
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2287 This function determines whether file @var{filename} is a text file
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2288 or a binary file. It returns @code{nil} for text, @code{t} for binary.
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2289 @end defun
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2290
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2291 @defopt file-name-buffer-file-type-alist
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2292 This variable holds an alist for distinguishing text files from binary
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2293 files. Each element has the form (@var{regexp} . @var{type}), where
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2294 @var{regexp} is matched against the file name, and @var{type} may be is
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2295 @code{nil} for text, @code{t} for binary, or a function to call to
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2296 compute which. If it is a function, then it is called with a single
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2297 argument (the file name) and should return @code{t} or @code{nil}.
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2298 @end defopt
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2299
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2300 @defopt default-buffer-file-type
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2301 This variable specifies the default file type for files whose names
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2302 don't indicate anything in particular. Its value should be @code{nil}
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2303 for text, or @code{t} for binary.
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2304 @end defopt
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2305
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2306 @deffn Command find-file-text filename
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2307 Like @code{find-file}, but treat the file as text regardless of its name.
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2308 @end deffn
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2309
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2310 @deffn Command find-file-binary filename
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2311 Like @code{find-file}, but treat the file as binary regardless of its
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2312 name.
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2313 @end deffn
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