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1 *diff.txt* For Vim version 7.2. Last change: 2008 Jul 21
4 VIM REFERENCE MANUAL by Bram Moolenaar
7 *diff* *vimdiff* *gvimdiff* *diff-mode*
8 This file describes the +diff feature: Showing differences between two,
9 three or four versions of the same file.
11 The basics are explained in section |08.7| of the user manual.
13 1. Starting diff mode |vimdiff|
14 2. Viewing diffs |view-diffs|
15 3. Jumping to diffs |jumpto-diffs|
16 4. Copying diffs |copy-diffs|
17 5. Diff options |diff-options|
19 {not in Vi}
21 ==============================================================================
22 1. Starting diff mode
24 The easiest way to start editing in diff mode is with the "vimdiff" command.
25 This starts Vim as usual, and additionally sets up for viewing the differences
26 between the arguments. >
28 vimdiff file1 file2 [file3 [file4]]
30 This is equivalent to: >
32 vim -d file1 file2 [file3 [file4]]
34 You may also use "gvimdiff" or "vim -d -g". The GUI is started then.
35 You may also use "viewdiff" or "gviewdiff". Vim starts in readonly mode then.
36 "r" may be prepended for restricted mode (see |-Z|).
38 The second and following arguments may also be a directory name. Vim will
39 then append the file name of the first argument to the directory name to find
40 the file.
42 This only works when a standard "diff" command is available. See 'diffexpr'.
44 Diffs are local to the current tab page |tab-page|. You can't see diffs with
45 a window in another tab page. This does make it possible to have several
46 diffs at the same time, each in their own tab page.
48 What happens is that Vim opens a window for each of the files. This is like
49 using the |-O| argument. This uses vertical splits. If you prefer horizontal
50 splits add the |-o| argument: >
52 vimdiff -o file1 file2 [file3 [file4]]
54 If you always prefer horizontal splits include "horizontal" in 'diffopt'.
56 In each of the edited files these options are set:
58 'diff' on
59 'scrollbind' on
60 'scrollopt' includes "hor"
61 'wrap' off
62 'foldmethod' "diff"
63 'foldcolumn' value from 'diffopt', default is 2
65 These options are set local to the window. When editing another file they are
66 reset to the global value.
68 The differences shown are actually the differences in the buffer. Thus if you
69 make changes after loading a file, these will be included in the displayed
70 diffs. You might have to do ":diffupdate" now and then, not all changes are
71 immediately taken into account.
73 In your .vimrc file you could do something special when Vim was started in
74 diff mode. You could use a construct like this: >
76 if &diff
77 setup for diff mode
78 else
79 setup for non-diff mode
80 endif
82 While already in Vim you can start diff mode in three ways.
84 *E98*
85 :diffsplit {filename} *:diffs* *:diffsplit*
86 Open a new window on the file {filename}. The options are set
87 as for "vimdiff" for the current and the newly opened window.
88 Also see 'diffexpr'.
90 *:difft* *:diffthis*
91 :diffthis Make the current window part of the diff windows. This sets
92 the options like for "vimdiff".
94 :diffpatch {patchfile} *:diffp* *:diffpatch*
95 Use the current buffer, patch it with the diff found in
96 {patchfile} and open a buffer on the result. The options are
97 set as for "vimdiff".
98 {patchfile} can be in any format that the "patch" program
99 understands or 'patchexpr' can handle.
100 Note that {patchfile} should only contain a diff for one file,
101 the current file. If {patchfile} contains diffs for other
102 files as well, the results are unpredictable. Vim changes
103 directory to /tmp to avoid files in the current directory
104 accidentally being patched. But it may still result in
105 various ".rej" files to be created. And when absolute path
106 names are present these files may get patched anyway.
108 To make these commands use a vertical split, prepend |:vertical|. Examples: >
110 :vert diffsplit main.c~
111 :vert diffpatch /tmp/diff
113 If you always prefer a vertical split include "vertical" in 'diffopt'.
115 *E96*
116 There can be up to four buffers with 'diff' set.
118 Since the option values are remembered with the buffer, you can edit another
119 file for a moment and come back to the same file and be in diff mode again.
121 *:diffo* *:diffoff*
122 :diffoff Switch off diff mode for the current window.
124 :diffoff! Switch off diff mode for all windows in the current tab page.
126 The ":diffoff" command resets the relevant options to their default value.
127 This may be different from what the values were before diff mode was started,
128 the old values are not remembered.
130 'diff' off
131 'scrollbind' off
132 'scrollopt' without "hor"
133 'wrap' on
134 'foldmethod' "manual"
135 'foldcolumn' 0
137 ==============================================================================
138 2. Viewing diffs *view-diffs*
140 The effect is that the diff windows show the same text, with the differences
141 highlighted. When scrolling the text, the 'scrollbind' option will make the
142 text in other windows to be scrolled as well. With vertical splits the text
143 should be aligned properly.
145 The alignment of text will go wrong when:
146 - 'wrap' is on, some lines will be wrapped and occupy two or more screen
147 lines
148 - folds are open in one window but not another
149 - 'scrollbind' is off
150 - changes have been made to the text
151 - "filler" is not present in 'diffopt', deleted/inserted lines makes the
152 alignment go wrong
154 All the buffers edited in a window where the 'diff' option is set will join in
155 the diff. This is also possible for hidden buffers. They must have been
156 edited in a window first for this to be possible.
158 *:DiffOrig* *diff-original-file*
159 Since 'diff' is a window-local option, it's possible to view the same buffer
160 in diff mode in one window and "normal" in another window. It is also
161 possible to view the changes you have made to a buffer since the file was
162 loaded. Since Vim doesn't allow having two buffers for the same file, you
163 need another buffer. This command is useful: >
164 command DiffOrig vert new | set bt=nofile | r # | 0d_ | diffthis
165 \ | wincmd p | diffthis
166 (this is in |vimrc_example.vim|). Use ":DiffOrig" to see the differences
167 between the current buffer and the file it was loaded from.
169 A buffer that is unloaded cannot be used for the diff. But it does work for
170 hidden buffers. You can use ":hide" to close a window without unloading the
171 buffer. If you don't want a buffer to remain used for the diff do ":set
172 nodiff" before hiding it.
174 *:diffu* *:diffupdate*
175 :diffu[pdate] Update the diff highlighting and folds.
177 Vim attempts to keep the differences updated when you make changes to the
178 text. This mostly takes care of inserted and deleted lines. Changes within a
179 line and more complicated changes do not cause the differences to be updated.
180 To force the differences to be updated use: >
182 :diffupdate
185 Vim will show filler lines for lines that are missing in one window but are
186 present in another. These lines were inserted in another file or deleted in
187 this file. Removing "filler" from the 'diffopt' option will make Vim not
188 display these filler lines.
191 Folds are used to hide the text that wasn't changed. See |folding| for all
192 the commands that can be used with folds.
194 The context of lines above a difference that are not included in the fold can
195 be set with the 'diffopt' option. For example, to set the context to three
196 lines: >
198 :set diffopt=filler,context:3
201 The diffs are highlighted with these groups:
203 |hl-DiffAdd| DiffAdd Added (inserted) lines. These lines exist in
204 this buffer but not in another.
205 |hl-DiffChange| DiffChange Changed lines.
206 |hl-DiffText| DiffText Changed text inside a Changed line. Vim
207 finds the first character that is different,
208 and the last character that is different
209 (searching from the end of the line). The
210 text in between is highlighted. This means
211 that parts in the middle that are still the
212 same are highlighted anyway. Only "iwhite" of
213 'diffopt' is used here.
214 |hl-DiffDelete| DiffDelete Deleted lines. Also called filler lines,
215 because they don't really exist in this
216 buffer.
218 ==============================================================================
219 3. Jumping to diffs *jumpto-diffs*
221 Two commands can be used to jump to diffs:
222 *[c*
223 [c Jump backwards to the previous start of a change.
224 When a count is used, do it that many times.
225 *]c*
226 ]c Jump forwards to the next start of a change.
227 When a count is used, do it that many times.
229 It is an error if there is no change for the cursor to move to.
231 ==============================================================================
232 4. Diff copying *copy-diffs* *E99* *E100* *E101* *E102* *E103*
233 *merge*
234 There are two commands to copy text from one buffer to another. The result is
235 that the buffers will be equal within the specified range.
237 *:diffg* *:diffget*
238 :[range]diffg[et] [bufspec]
239 Modify the current buffer to undo difference with another
240 buffer. If [bufspec] is given, that buffer is used.
241 Otherwise this only works if there is one other buffer in diff
242 mode.
243 See below for [range].
245 *:diffpu* *:diffput* *E793*
246 :[range]diffpu[t] [bufspec]
247 Modify another buffer to undo difference with the current
248 buffer. Just like ":diffget" but the other buffer is modified
249 instead of the current one.
250 When [bufspec] is omitted and there is more than one other
251 buffer in diff mode where 'modifiable' is set this fails.
252 See below for [range].
254 *do*
255 do Same as ":diffget" without argument or range. The "o" stands
256 for "obtain" ("dg" can't be used, it could be the start of
257 "dgg"!).
259 *dp*
260 dp Same as ":diffput" without argument or range.
262 When no [range] is given, the diff at the cursor position or just above it is
263 affected. When [range] is used, Vim tries to only put or get the specified
264 lines. When there are deleted lines, this may not always be possible.
266 There can be deleted lines below the last line of the buffer. When the cursor
267 is on the last line in the buffer and there is no diff above this line, the
268 ":diffget" and "do" commands will obtain lines from the other buffer.
270 To be able to get those lines from another buffer in a [range] it's allowed to
271 use the last line number plus one. This command gets all diffs from the other
272 buffer: >
274 :1,$+1diffget
276 Note that deleted lines are displayed, but not counted as text lines. You
277 can't move the cursor into them. To fill the deleted lines with the lines
278 from another buffer use ":diffget" on the line below them.
279 *E787*
280 When the buffer that is about to be modified is read-only and the autocommand
281 that is triggered by |FileChangedRO| changes buffers the command will fail.
282 The autocommand must not change buffers.
284 The [bufspec] argument above can be a buffer number, a pattern for a buffer
285 name or a part of a buffer name. Examples:
287 :diffget Use the other buffer which is in diff mode
288 :diffget 3 Use buffer 3
289 :diffget v2 Use the buffer which matches "v2" and is in
290 diff mode (e.g., "file.c.v2")
292 ==============================================================================
293 5. Diff options *diff-options*
295 Also see |'diffopt'| and the "diff" item of |'fillchars'|.
298 FINDING THE DIFFERENCES *diff-diffexpr*
300 The 'diffexpr' option can be set to use something else than the standard
301 "diff" program to compare two files and find the differences.
303 When 'diffexpr' is empty, Vim uses this command to find the differences
304 between file1 and file2: >
306 diff file1 file2 > outfile
308 The ">" is replaced with the value of 'shellredir'.
310 The output of "diff" must be a normal "ed" style diff. Do NOT use a context
311 diff. This example explains the format that Vim expects: >
313 1a2
314 > bbb
315 4d4
316 < 111
317 7c7
318 < GGG
319 ---
320 > ggg
322 The "1a2" item appends the line "bbb".
323 The "4d4" item deletes the line "111".
324 The '7c7" item replaces the line "GGG" with "ggg".
326 When 'diffexpr' is not empty, Vim evaluates to obtain a diff file in the
327 format mentioned. These variables are set to the file names used:
329 v:fname_in original file
330 v:fname_new new version of the same file
331 v:fname_out resulting diff file
333 Additionally, 'diffexpr' should take care of "icase" and "iwhite" in the
334 'diffopt' option. 'diffexpr' cannot change the value of 'lines' and
335 'columns'.
337 Example (this does almost the same as 'diffexpr' being empty): >
339 set diffexpr=MyDiff()
340 function MyDiff()
341 let opt = ""
342 if &diffopt =~ "icase"
343 let opt = opt . "-i "
344 endif
345 if &diffopt =~ "iwhite"
346 let opt = opt . "-b "
347 endif
348 silent execute "!diff -a --binary " . opt . v:fname_in . " " . v:fname_new .
349 \ " > " . v:fname_out
350 endfunction
352 The "-a" argument is used to force comparing the files as text, comparing as
353 binaries isn't useful. The "--binary" argument makes the files read in binary
354 mode, so that a CTRL-Z doesn't end the text on DOS.
356 *E97*
357 Vim will do a test if the diff output looks alright. If it doesn't, you will
358 get an error message. Possible causes:
359 - The "diff" program cannot be executed.
360 - The "diff" program doesn't produce normal "ed" style diffs (see above).
361 - The 'shell' and associated options are not set correctly. Try if filtering
362 works with a command like ":!sort".
363 - You are using 'diffexpr' and it doesn't work.
364 If it's not clear what the problem is set the 'verbose' option to one or more
365 to see more messages.
367 The self-installing Vim includes a diff program. If you don't have it you
368 might want to download a diff.exe. For example from
369 http://jlb.twu.net/code/unixkit.php.
372 USING PATCHES *diff-patchexpr*
374 The 'patchexpr' option can be set to use something else than the standard
375 "patch" program.
377 When 'patchexpr' is empty, Vim will call the "patch" program like this: >
379 patch -o outfile origfile < patchfile
381 This should work fine with most versions of the "patch" program. Note that a
382 CR in the middle of a line may cause problems, it is seen as a line break.
384 If the default doesn't work for you, set the 'patchexpr' to an expression that
385 will have the same effect. These variables are set to the file names used:
387 v:fname_in original file
388 v:fname_diff patch file
389 v:fname_out resulting patched file
391 Example (this does the same as 'patchexpr' being empty): >
393 set patchexpr=MyPatch()
394 function MyPatch()
395 :call system("patch -o " . v:fname_out . " " . v:fname_in .
396 \ " < " . v:fname_diff)
397 endfunction
399 Make sure that using the "patch" program doesn't have unwanted side effects.
400 For example, watch out for additionally generated files, which should be
401 deleted. It should just patch the file and nothing else.
402 Vim will change directory to "/tmp" or another temp directory before
403 evaluating 'patchexpr'. This hopefully avoids that files in the current
404 directory are accidentally patched. Vim will also delete files starting with
405 v:fname_in and ending in ".rej" and ".orig".
407 vim:tw=78:ts=8:ft=help:norl: