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1 *diff.txt* For Vim version 7.2. Last change: 2009 Jan 14
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. If
241 [bufspec] refers to the current buffer then nothing happens.
242 Otherwise this only works if there is one other buffer in diff
243 mode.
244 See below for [range].
246 *:diffpu* *:diffput* *E793*
247 :[range]diffpu[t] [bufspec]
248 Modify another buffer to undo difference with the current
249 buffer. Just like ":diffget" but the other buffer is modified
250 instead of the current one.
251 When [bufspec] is omitted and there is more than one other
252 buffer in diff mode where 'modifiable' is set this fails.
253 See below for [range].
255 *do*
256 do Same as ":diffget" without argument or range. The "o" stands
257 for "obtain" ("dg" can't be used, it could be the start of
258 "dgg"!).
260 *dp*
261 dp Same as ":diffput" without argument or range.
263 When no [range] is given, the diff at the cursor position or just above it is
264 affected. When [range] is used, Vim tries to only put or get the specified
265 lines. When there are deleted lines, this may not always be possible.
267 There can be deleted lines below the last line of the buffer. When the cursor
268 is on the last line in the buffer and there is no diff above this line, the
269 ":diffget" and "do" commands will obtain lines from the other buffer.
271 To be able to get those lines from another buffer in a [range] it's allowed to
272 use the last line number plus one. This command gets all diffs from the other
273 buffer: >
275 :1,$+1diffget
277 Note that deleted lines are displayed, but not counted as text lines. You
278 can't move the cursor into them. To fill the deleted lines with the lines
279 from another buffer use ":diffget" on the line below them.
280 *E787*
281 When the buffer that is about to be modified is read-only and the autocommand
282 that is triggered by |FileChangedRO| changes buffers the command will fail.
283 The autocommand must not change buffers.
285 The [bufspec] argument above can be a buffer number, a pattern for a buffer
286 name or a part of a buffer name. Examples:
288 :diffget Use the other buffer which is in diff mode
289 :diffget 3 Use buffer 3
290 :diffget v2 Use the buffer which matches "v2" and is in
291 diff mode (e.g., "file.c.v2")
293 ==============================================================================
294 5. Diff options *diff-options*
296 Also see |'diffopt'| and the "diff" item of |'fillchars'|.
299 FINDING THE DIFFERENCES *diff-diffexpr*
301 The 'diffexpr' option can be set to use something else than the standard
302 "diff" program to compare two files and find the differences.
304 When 'diffexpr' is empty, Vim uses this command to find the differences
305 between file1 and file2: >
307 diff file1 file2 > outfile
309 The ">" is replaced with the value of 'shellredir'.
311 The output of "diff" must be a normal "ed" style diff. Do NOT use a context
312 diff. This example explains the format that Vim expects: >
314 1a2
315 > bbb
316 4d4
317 < 111
318 7c7
319 < GGG
320 ---
321 > ggg
323 The "1a2" item appends the line "bbb".
324 The "4d4" item deletes the line "111".
325 The '7c7" item replaces the line "GGG" with "ggg".
327 When 'diffexpr' is not empty, Vim evaluates to obtain a diff file in the
328 format mentioned. These variables are set to the file names used:
330 v:fname_in original file
331 v:fname_new new version of the same file
332 v:fname_out resulting diff file
334 Additionally, 'diffexpr' should take care of "icase" and "iwhite" in the
335 'diffopt' option. 'diffexpr' cannot change the value of 'lines' and
336 'columns'.
338 Example (this does almost the same as 'diffexpr' being empty): >
340 set diffexpr=MyDiff()
341 function MyDiff()
342 let opt = ""
343 if &diffopt =~ "icase"
344 let opt = opt . "-i "
345 endif
346 if &diffopt =~ "iwhite"
347 let opt = opt . "-b "
348 endif
349 silent execute "!diff -a --binary " . opt . v:fname_in . " " . v:fname_new .
350 \ " > " . v:fname_out
351 endfunction
353 The "-a" argument is used to force comparing the files as text, comparing as
354 binaries isn't useful. The "--binary" argument makes the files read in binary
355 mode, so that a CTRL-Z doesn't end the text on DOS.
357 *E810* *E97*
358 Vim will do a test if the diff output looks alright. If it doesn't, you will
359 get an error message. Possible causes:
360 - The "diff" program cannot be executed.
361 - The "diff" program doesn't produce normal "ed" style diffs (see above).
362 - The 'shell' and associated options are not set correctly. Try if filtering
363 works with a command like ":!sort".
364 - You are using 'diffexpr' and it doesn't work.
365 If it's not clear what the problem is set the 'verbose' option to one or more
366 to see more messages.
368 The self-installing Vim includes a diff program. If you don't have it you
369 might want to download a diff.exe. For example from
370 http://jlb.twu.net/code/unixkit.php.
373 USING PATCHES *diff-patchexpr*
375 The 'patchexpr' option can be set to use something else than the standard
376 "patch" program.
378 When 'patchexpr' is empty, Vim will call the "patch" program like this: >
380 patch -o outfile origfile < patchfile
382 This should work fine with most versions of the "patch" program. Note that a
383 CR in the middle of a line may cause problems, it is seen as a line break.
385 If the default doesn't work for you, set the 'patchexpr' to an expression that
386 will have the same effect. These variables are set to the file names used:
388 v:fname_in original file
389 v:fname_diff patch file
390 v:fname_out resulting patched file
392 Example (this does the same as 'patchexpr' being empty): >
394 set patchexpr=MyPatch()
395 function MyPatch()
396 :call system("patch -o " . v:fname_out . " " . v:fname_in .
397 \ " < " . v:fname_diff)
398 endfunction
400 Make sure that using the "patch" program doesn't have unwanted side effects.
401 For example, watch out for additionally generated files, which should be
402 deleted. It should just patch the file and nothing else.
403 Vim will change directory to "/tmp" or another temp directory before
404 evaluating 'patchexpr'. This hopefully avoids that files in the current
405 directory are accidentally patched. Vim will also delete files starting with
406 v:fname_in and ending in ".rej" and ".orig".
408 vim:tw=78:ts=8:ft=help:norl: