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comparison man/new-users-guide/files.texi @ 0:376386a54a3c r19-14
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date | Mon, 13 Aug 2007 08:45:50 +0200 |
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1 @comment node-name, next, previous, up | |
2 @node Files, Other Customizations, Modes, Top | |
3 @chapter Files | |
4 @cindex files | |
5 | |
6 The basic unit of stored data in Unix is the @dfn{file}. To edit a file, | |
7 you must tell Emacs to read the file into a buffer. This is called | |
8 @dfn{visiting} the file. You can now edit the buffer and to save the | |
9 changes you must write the buffer back to the file. | |
10 | |
11 In addition to visiting and saving files, Emacs can delete, copy, rename, | |
12 and append to files, and operate on file directories. | |
13 | |
14 @comment node-name, next, previous, up | |
15 @menu | |
16 * File Names:: How to type and edit file name arguments. | |
17 * Visiting:: Visiting a file prepares Emacs to edit the file. | |
18 * Saving Files:: How to save Emacs files. | |
19 @end menu | |
20 | |
21 @node File Names, Visiting, Files, Files | |
22 @section File Names | |
23 @cindex file names | |
24 | |
25 Most of the Emacs commands that operate on a file require you to | |
26 specify a file name. For example, you might specify the file name | |
27 initially when you enter Emacs : | |
28 | |
29 @example | |
30 xemacs myfile RET | |
31 @end example | |
32 | |
33 @noindent | |
34 After you hit @key{RET}, you will enter XEmacs with "myfile" read into | |
35 the current buffer. If you do not specify the filename when entering | |
36 Emacs, you can use the @b{Open...} option from the @b{File} menu. You | |
37 will be prompted for a filename in the echo area: | |
38 | |
39 @example | |
40 Find file: /usr/workspace/ | |
41 @end example | |
42 | |
43 @vindex default-directory | |
44 @noindent | |
45 Type in a file name which you want to open after the "/" and hit | |
46 @key{RET}. The specified file will be read into the current buffer. The | |
47 "/usr/workspace" might be the @dfn{default directory}. When Emacs | |
48 prompts you for a file, it uses the default-directory unless you specify | |
49 a directory. You can see what the default directory of the current | |
50 buffer is by using the @b{Describe Variable} option from the @b{Help} | |
51 menu. When Emacs prompts you for the variable name to describe, type | |
52 @var{default-directory}. If you wish to open a file in some other | |
53 directory, use @key{DEL} or the @key{BackSpace} key to go back and type | |
54 the path name of the new directory. | |
55 | |
56 You can create a new directory by typing @kbd{M-x | |
57 make-directory}. This command will prompt you for a directory name: | |
58 | |
59 @example | |
60 Create directory: /usr/workspace/ | |
61 @end example | |
62 | |
63 @findex make-directory | |
64 @findex remove-directory | |
65 @cindex creating-directories | |
66 @cindex removing-directories | |
67 @noindent | |
68 After you type a directory name and press @key{RET}, a new directory | |
69 with the specified name will be created. If you do not wish to create a | |
70 new directory, then simply press @kbd{C-g} to quit the | |
71 command. Similarly, you can also remove a directory by using the command | |
72 @kbd{remove-directory}. The command @kbd{M-x pwd} will print the current | |
73 buffer's default directory. For more information on file names, | |
74 @xref{File Names,,,,XEmacs User's Manual}. | |
75 | |
76 | |
77 @node Visiting, Saving Files, File Names, Files | |
78 @section Visiting Files | |
79 @cindex visiting files | |
80 | |
81 To edit a file in Emacs you need to @dfn{visit} it. @dfn{Visiting} a | |
82 file means copying its contents (or reading them) into the current | |
83 buffer. Emacs will create a new buffer for each file that you visit. The | |
84 buffer will be named after the file that you open. If you open a file | |
85 @file{/usr/workspace/myfile.texinfo}, the buffer will be called | |
86 "myfile.texinfo". If a buffer with this name already exists, a unique | |
87 name will be constructed by appending @samp{<2>}, @samp{<3>}, etc. If | |
88 this is the second buffer with the same name, a "<2>" will be appended, | |
89 "<3>" for a third buffer and so on. The name of the buffer which is | |
90 being displayed in the window will be shown both at the top and bottom | |
91 of the frame. Once you are in XEmacs, you can use the following | |
92 commands: | |
93 | |
94 @table @kbd | |
95 @item C-x C-f | |
96 @findex find-file | |
97 @kindex C-x C-f | |
98 This command will visit a file (@code{find-file}). It will prompt you | |
99 for a file name to visit. The @b{Open...} option from the @b{File} menu | |
100 does the same thing: | |
101 | |
102 @example | |
103 Find file: /usr/workspace/ | |
104 @end example | |
105 | |
106 @noindent | |
107 Type in a filename and press @key{RET}. You will see a new buffer on the | |
108 screen with its name in the mode-line. If the filename you specify | |
109 already exists in Emacs, the buffer containing that file will be | |
110 selected. You will get an error message if the filename does not | |
111 exist. If you still press @key{RET}, a new buffer with the given | |
112 filename will be displayed on the screen. | |
113 | |
114 @item C-x C-v | |
115 @kindex C-x C-v | |
116 @findex find-alternate-file | |
117 This command (@code{find-alternate-file}), will visit a different file | |
118 instead of the one visited last. It is similar to @kbd{C-c C-f} except | |
119 that it kills the current buffer (after offering to save it). | |
120 | |
121 @item C-x 5 C-f | |
122 @kindex C-x 5 C-f | |
123 @findex find-file-other-frame | |
124 This command will visit a file in another frame | |
125 (@code{find-file-other-frame}) without changing the current window or | |
126 frame. The @b{Open in New Frame...} from the @b{File} menu will do the | |
127 same thing. It will prompt you for a file name in the echo area. After | |
128 you type the file name and press @key{RET}, the specified file will be | |
129 read into a new buffer and displayed on a new frame. | |
130 @end table | |
131 | |
132 @node Saving Files, , Visiting, Files | |
133 @section Saving Files | |
134 @cindex saving files | |
135 | |
136 The changes that you make after visiting a file will not be saved | |
137 unless you save the buffer. When you save the buffer, Emacs writes the | |
138 current contents of the buffer into the visited file. Some commands to | |
139 save buffers are: | |
140 | |
141 @table @kbd | |
142 @item C-x C-s | |
143 @findex save-buffer | |
144 @kindex C-x C-s | |
145 This command will permanently save the current buffer in its visited | |
146 file (@code{save-buffer}). You will see the following message in the | |
147 echo area if you save a file called "myfile.texinfo" : | |
148 | |
149 @example | |
150 Wrote /usr/workspace/myfile.texinfo | |
151 @end example | |
152 | |
153 @noindent | |
154 Try using this command twice. You will get the above message the first | |
155 time you use this command, the second time you will get the following | |
156 message: | |
157 | |
158 @example | |
159 (No changes need to be saved) | |
160 @end example | |
161 | |
162 @noindent | |
163 This message indicates that you haven't made any changes since the last | |
164 time you saved the file. | |
165 | |
166 @item C-x s | |
167 @kindex C-x s | |
168 @findex save-some-buffers | |
169 This command will save all the buffers in their visited files | |
170 (@code{save-some-buffers}). It will prompt you for typing yes or no: | |
171 | |
172 @example | |
173 Save file /usr/workspace/myfile.texinfo? (y or n) | |
174 @end example | |
175 | |
176 @noindent | |
177 You will get the above message for all the buffers. Type "y" if you want | |
178 to save the buffer. | |
179 | |
180 @item C-x C-w | |
181 @findex write file | |
182 @kindex C-x C-w | |
183 This command will prompt you for a file name and save the current buffer | |
184 in that file. (@code{write-file}). You will see the following message in | |
185 the echo area: | |
186 | |
187 @example | |
188 Write file: /usr/workspace/ | |
189 @end example | |
190 | |
191 @noindent | |
192 After you type in a file name, press @key{RET}. The buffer will be saved | |
193 in a new file. You can make copies of a particular file using this | |
194 command. | |
195 @end table | |
196 | |
197 You can also undo all the changes made since the file was visited or | |
198 saved by reading the text from the file again (called | |
199 @dfn{reverting}). For more information on this option, | |
200 @xref{Reverting,,,,XEmacs User's Manual}. | |
201 | |
202 @vindex make-backup-files | |
203 When you save a file in Emacs, it destroys its old contents. However, | |
204 if you set the variable @var{make-backup-files} to non-@var{nil} | |
205 i.e. @samp{t}, Emacs will create a @dfn{backup} file. Select the | |
206 @b{Describe variable} option from the @b{Help} menu and look at the | |
207 documentation for this variable. Its default value should be | |
208 @samp{t}. However, if its not then use @kbd{M-x set-variable} to set it | |
209 to @samp{t} (@pxref{Setting Variables}). The backup file will contain | |
210 the contents from the last time you visited the file. Emacs also | |
211 provides options for creating numbered backups. For more information on | |
212 backups, @xref{Backup,,,,XEmacs User's Manual}. | |
213 | |
214 @cindex auto saving | |
215 Emacs also saves all the files from time to time so that in case of a | |
216 system crash you don't lose lot of your work. You will see the message | |
217 @samp{Auto-saving...} displayed in the echo area when the buffer is | |
218 being saved automatically. The auto saved files are named by putting the | |
219 character @samp{#} in front and back. For example a file called | |
220 "myfile.texinfo" would be named as @file{#myfile.texinfo#}. For | |
221 information on controlling auto-saving and recovering data from | |
222 auto-saving, @xref{Auto Save Files,,,,XEmacs User's Manual}. | |
223 | |
224 @cindex simultaneous editing | |
225 Emacs provides protection from simultaneous editing which occurs if | |
226 two users are visiting the same file and trying to save their | |
227 changes. It will put a lock on a file which is being visited and | |
228 modified. If any other user tries to modify that file, it will inform | |
229 the user about the lock and provide some | |
230 options. For more information on protection against simultaneous | |
231 editing, @xref{Interlocking,,,,XEmacs User's Manual}. | |
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