1 *diff.txt* For Vim version 7.3. Last change: 2011 Apr 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|
21 ==============================================================================
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
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:
61 'scrollopt' includes "hor"
64 'foldcolumn' value from 'diffopt', default is 2
66 These options are set local to the window. When editing another file they are
67 reset to the global value.
68 The options can still be overruled from a modeline when re-editing the file.
69 However, 'foldmethod' and 'wrap' won't be set from a modeline when 'diff' is
72 The differences shown are actually the differences in the buffer. Thus if you
73 make changes after loading a file, these will be included in the displayed
74 diffs. You might have to do ":diffupdate" now and then, not all changes are
75 immediately taken into account.
77 In your .vimrc file you could do something special when Vim was started in
78 diff mode. You could use a construct like this: >
83 setup for non-diff mode
86 While already in Vim you can start diff mode in three ways.
89 :diffsplit {filename} *:diffs* *:diffsplit*
90 Open a new window on the file {filename}. The options are set
91 as for "vimdiff" for the current and the newly opened window.
95 :diffthis Make the current window part of the diff windows. This sets
96 the options like for "vimdiff".
98 :diffpatch {patchfile} *E816* *:diffp* *:diffpatch*
99 Use the current buffer, patch it with the diff found in
100 {patchfile} and open a buffer on the result. The options are
101 set as for "vimdiff".
102 {patchfile} can be in any format that the "patch" program
103 understands or 'patchexpr' can handle.
104 Note that {patchfile} should only contain a diff for one file,
105 the current file. If {patchfile} contains diffs for other
106 files as well, the results are unpredictable. Vim changes
107 directory to /tmp to avoid files in the current directory
108 accidentally being patched. But it may still result in
109 various ".rej" files to be created. And when absolute path
110 names are present these files may get patched anyway.
112 To make these commands use a vertical split, prepend |:vertical|. Examples: >
114 :vert diffsplit main.c~
115 :vert diffpatch /tmp/diff
117 If you always prefer a vertical split include "vertical" in 'diffopt'.
120 There can be up to four buffers with 'diff' set.
122 Since the option values are remembered with the buffer, you can edit another
123 file for a moment and come back to the same file and be in diff mode again.
126 :diffoff Switch off diff mode for the current window.
128 :diffoff! Switch off diff mode for the current window and in all windows
129 in the current tab page where 'diff' is set.
131 The ":diffoff" command resets the relevant options to their default value.
132 This may be different from what the values were before diff mode was started,
133 the old values are not remembered.
138 'scrollopt' without "hor"
140 'foldmethod' "manual"
143 ==============================================================================
144 2. Viewing diffs *view-diffs*
146 The effect is that the diff windows show the same text, with the differences
147 highlighted. When scrolling the text, the 'scrollbind' option will make the
148 text in other windows to be scrolled as well. With vertical splits the text
149 should be aligned properly.
151 The alignment of text will go wrong when:
152 - 'wrap' is on, some lines will be wrapped and occupy two or more screen
154 - folds are open in one window but not another
155 - 'scrollbind' is off
156 - changes have been made to the text
157 - "filler" is not present in 'diffopt', deleted/inserted lines makes the
160 All the buffers edited in a window where the 'diff' option is set will join in
161 the diff. This is also possible for hidden buffers. They must have been
162 edited in a window first for this to be possible.
164 *:DiffOrig* *diff-original-file*
165 Since 'diff' is a window-local option, it's possible to view the same buffer
166 in diff mode in one window and "normal" in another window. It is also
167 possible to view the changes you have made to a buffer since the file was
168 loaded. Since Vim doesn't allow having two buffers for the same file, you
169 need another buffer. This command is useful: >
170 command DiffOrig vert new | set bt=nofile | r ++edit # | 0d_
171 \ | diffthis | wincmd p | diffthis
172 (this is in |vimrc_example.vim|). Use ":DiffOrig" to see the differences
173 between the current buffer and the file it was loaded from.
175 A buffer that is unloaded cannot be used for the diff. But it does work for
176 hidden buffers. You can use ":hide" to close a window without unloading the
177 buffer. If you don't want a buffer to remain used for the diff do ":set
178 nodiff" before hiding it.
180 *:diffu* *:diffupdate*
181 :diffu[pdate] Update the diff highlighting and folds.
183 Vim attempts to keep the differences updated when you make changes to the
184 text. This mostly takes care of inserted and deleted lines. Changes within a
185 line and more complicated changes do not cause the differences to be updated.
186 To force the differences to be updated use: >
191 Vim will show filler lines for lines that are missing in one window but are
192 present in another. These lines were inserted in another file or deleted in
193 this file. Removing "filler" from the 'diffopt' option will make Vim not
194 display these filler lines.
197 Folds are used to hide the text that wasn't changed. See |folding| for all
198 the commands that can be used with folds.
200 The context of lines above a difference that are not included in the fold can
201 be set with the 'diffopt' option. For example, to set the context to three
204 :set diffopt=filler,context:3
207 The diffs are highlighted with these groups:
209 |hl-DiffAdd| DiffAdd Added (inserted) lines. These lines exist in
210 this buffer but not in another.
211 |hl-DiffChange| DiffChange Changed lines.
212 |hl-DiffText| DiffText Changed text inside a Changed line. Vim
213 finds the first character that is different,
214 and the last character that is different
215 (searching from the end of the line). The
216 text in between is highlighted. This means
217 that parts in the middle that are still the
218 same are highlighted anyway. Only "iwhite" of
219 'diffopt' is used here.
220 |hl-DiffDelete| DiffDelete Deleted lines. Also called filler lines,
221 because they don't really exist in this
224 ==============================================================================
225 3. Jumping to diffs *jumpto-diffs*
227 Two commands can be used to jump to diffs:
229 [c Jump backwards to the previous start of a change.
230 When a count is used, do it that many times.
232 ]c Jump forwards to the next start of a change.
233 When a count is used, do it that many times.
235 It is an error if there is no change for the cursor to move to.
237 ==============================================================================
238 4. Diff copying *copy-diffs* *E99* *E100* *E101* *E102* *E103*
240 There are two commands to copy text from one buffer to another. The result is
241 that the buffers will be equal within the specified range.
244 :[range]diffg[et] [bufspec]
245 Modify the current buffer to undo difference with another
246 buffer. If [bufspec] is given, that buffer is used. If
247 [bufspec] refers to the current buffer then nothing happens.
248 Otherwise this only works if there is one other buffer in diff
250 See below for [range].
252 *:diffpu* *:diffput* *E793*
253 :[range]diffpu[t] [bufspec]
254 Modify another buffer to undo difference with the current
255 buffer. Just like ":diffget" but the other buffer is modified
256 instead of the current one.
257 When [bufspec] is omitted and there is more than one other
258 buffer in diff mode where 'modifiable' is set this fails.
259 See below for [range].
262 do Same as ":diffget" without argument or range. The "o" stands
263 for "obtain" ("dg" can't be used, it could be the start of
264 "dgg"!). Note: this doesn't work in Visual mode.
267 dp Same as ":diffput" without argument or range.
268 Note: this doesn't work in Visual mode.
271 When no [range] is given, the diff at the cursor position or just above it is
272 affected. When [range] is used, Vim tries to only put or get the specified
273 lines. When there are deleted lines, this may not always be possible.
275 There can be deleted lines below the last line of the buffer. When the cursor
276 is on the last line in the buffer and there is no diff above this line, the
277 ":diffget" and "do" commands will obtain lines from the other buffer.
279 To be able to get those lines from another buffer in a [range] it's allowed to
280 use the last line number plus one. This command gets all diffs from the other
285 Note that deleted lines are displayed, but not counted as text lines. You
286 can't move the cursor into them. To fill the deleted lines with the lines
287 from another buffer use ":diffget" on the line below them.
289 When the buffer that is about to be modified is read-only and the autocommand
290 that is triggered by |FileChangedRO| changes buffers the command will fail.
291 The autocommand must not change buffers.
293 The [bufspec] argument above can be a buffer number, a pattern for a buffer
294 name or a part of a buffer name. Examples:
296 :diffget Use the other buffer which is in diff mode
297 :diffget 3 Use buffer 3
298 :diffget v2 Use the buffer which matches "v2" and is in
299 diff mode (e.g., "file.c.v2")
301 ==============================================================================
302 5. Diff options *diff-options*
304 Also see |'diffopt'| and the "diff" item of |'fillchars'|.
307 FINDING THE DIFFERENCES *diff-diffexpr*
309 The 'diffexpr' option can be set to use something else than the standard
310 "diff" program to compare two files and find the differences.
312 When 'diffexpr' is empty, Vim uses this command to find the differences
313 between file1 and file2: >
315 diff file1 file2 > outfile
317 The ">" is replaced with the value of 'shellredir'.
319 The output of "diff" must be a normal "ed" style diff. Do NOT use a context
320 diff. This example explains the format that Vim expects: >
331 The "1a2" item appends the line "bbb".
332 The "4d4" item deletes the line "111".
333 The '7c7" item replaces the line "GGG" with "ggg".
335 When 'diffexpr' is not empty, Vim evaluates it to obtain a diff file in the
336 format mentioned. These variables are set to the file names used:
338 v:fname_in original file
339 v:fname_new new version of the same file
340 v:fname_out resulting diff file
342 Additionally, 'diffexpr' should take care of "icase" and "iwhite" in the
343 'diffopt' option. 'diffexpr' cannot change the value of 'lines' and
346 Example (this does almost the same as 'diffexpr' being empty): >
348 set diffexpr=MyDiff()
351 if &diffopt =~ "icase"
352 let opt = opt . "-i "
354 if &diffopt =~ "iwhite"
355 let opt = opt . "-b "
357 silent execute "!diff -a --binary " . opt . v:fname_in . " " . v:fname_new .
358 \ " > " . v:fname_out
361 The "-a" argument is used to force comparing the files as text, comparing as
362 binaries isn't useful. The "--binary" argument makes the files read in binary
363 mode, so that a CTRL-Z doesn't end the text on DOS.
366 Vim will do a test if the diff output looks alright. If it doesn't, you will
367 get an error message. Possible causes:
368 - The "diff" program cannot be executed.
369 - The "diff" program doesn't produce normal "ed" style diffs (see above).
370 - The 'shell' and associated options are not set correctly. Try if filtering
371 works with a command like ":!sort".
372 - You are using 'diffexpr' and it doesn't work.
373 If it's not clear what the problem is set the 'verbose' option to one or more
374 to see more messages.
376 The self-installing Vim for MS-Windows includes a diff program. If you don't
377 have it you might want to download a diff.exe. For example from
378 http://gnuwin32.sourceforge.net/packages/diffutils.htm.
381 USING PATCHES *diff-patchexpr*
383 The 'patchexpr' option can be set to use something else than the standard
386 When 'patchexpr' is empty, Vim will call the "patch" program like this: >
388 patch -o outfile origfile < patchfile
390 This should work fine with most versions of the "patch" program. Note that a
391 CR in the middle of a line may cause problems, it is seen as a line break.
393 If the default doesn't work for you, set the 'patchexpr' to an expression that
394 will have the same effect. These variables are set to the file names used:
396 v:fname_in original file
397 v:fname_diff patch file
398 v:fname_out resulting patched file
400 Example (this does the same as 'patchexpr' being empty): >
402 set patchexpr=MyPatch()
404 :call system("patch -o " . v:fname_out . " " . v:fname_in .
405 \ " < " . v:fname_diff)
408 Make sure that using the "patch" program doesn't have unwanted side effects.
409 For example, watch out for additionally generated files, which should be
410 deleted. It should just patch the file and nothing else.
411 Vim will change directory to "/tmp" or another temp directory before
412 evaluating 'patchexpr'. This hopefully avoids that files in the current
413 directory are accidentally patched. Vim will also delete files starting with
414 v:fname_in and ending in ".rej" and ".orig".
416 vim:tw=78:ts=8:ft=help:norl: