*diff.txt*      For Vim version 7.1.  Last change: 2006 Oct 02  		  VIM REFERENCE MANUAL    by Bram Moolenaar  				*diff* *vimdiff* *gvimdiff* *diff-mode*This file describes the +diff feature: Showing differences between two orthree versions of the same file. The basics are explained in section |08.7| of the user manual. 1. Starting diff mode		|vimdiff|2. Viewing diffs		|view-diffs|3. Jumping to diffs		|jumpto-diffs|4. Copying diffs		|copy-diffs|5. Diff options			|diff-options| {not in Vi} ==============================================================================1. Starting diff mode The easiest way to start editing in diff mode is with the "vimdiff" command.This starts Vim as usual, and additionally sets up for viewing the differencesbetween the arguments. > 	vimdiff file1 file2 [file3 [file4]] This is equivalent to: > 	vim -d file1 file2 [file3 [file4]] You may also use "gvimdiff" or "vim -d -g".  The GUI is started then.You may also use "viewdiff" or "gviewdiff".  Vim starts in readonly mode then."r" may be prepended for restricted mode (see |-Z|). The second and following arguments may also be a directory name.  Vim willthen append the file name of the first argument to the directory name to findthe file. This only works when a standard "diff" command is available.  See 'diffexpr'. Diffs are local to the current tab page |tab-page|.  You can't see diffs witha window in another tab page.  This does make it possible to have severaldiffs at the same time, each in their own tab page. What happens is that Vim opens a window for each of the files.  This is likeusing the |-O| argument.  This uses vertical splits.  If you prefer horizontalsplits add the |-o| argument: > 	vimdiff -o file1 file2 [file3] If you always prefer horizontal splits include "horizontal" in 'diffopt'. In each of the edited files these options are set: 	'diff'		on	'scrollbind'	on	'scrollopt'	includes "hor"	'wrap'		off	'foldmethod'	"diff"	'foldcolumn'	value from 'diffopt', default is 2 These options are set local to the window.  When editing another file they arereset to the global value. The differences shown are actually the differences in the buffer.  Thus if youmake changes after loading a file, these will be included in the displayeddiffs.  You might have to do ":diffupdate" now and then, not all changes areimmediately taken into account. In your .vimrc file you could do something special when Vim was started indiff mode.  You could use a construct like this: > 	if &diff	   setup for diff mode	else	   setup for non-diff mode	endif While already in Vim you can start diff mode in three ways. 							*E98*:diffsplit {filename}					*:diffs* *:diffsplit*		Open a new window on the file {filename}.  The options are set		as for "vimdiff" for the current and the newly opened window.		Also see 'diffexpr'. 							*:difft* *:diffthis*:diffthis	Make the current window part of the diff windows.  This sets		the options like for "vimdiff". :diffpatch {patchfile}					*:diffp* *:diffpatch*		Use the current buffer, patch it with the diff found in		{patchfile} and open a buffer on the result.  The options are		set as for "vimdiff".		{patchfile} can be in any format that the "patch" program		understands or 'patchexpr' can handle.		Note that {patchfile} should only contain a diff for one file,		the current file.  If {patchfile} contains diffs for other		files as well, the results are unpredictable.  Vim changes		directory to /tmp to avoid files in the current directory		accidentally being patched.  But it may still result in		various ".rej" files to be created.  And when absolute path		names are present these files may get patched anyway. To make these commands use a vertical split, prepend |:vertical|.  Examples: > 	:vert diffsplit main.c~	:vert diffpatch /tmp/diff If you always prefer a vertical split include "vertical" in 'diffopt'. 							*E96*There can be up to four buffers with 'diff' set. Since the option values are remembered with the buffer, you can edit anotherfile for a moment and come back to the same file and be in diff mode again. 							*:diffo* *:diffoff*:diffoff	Switch off diff mode for the current window. :diffoff!	Switch off diff mode for all windows in the current tab page. The ":diffoff" command resets the relevant options to their default value.This may be different from what the values were before diff mode was started,the old values are not remembered. 	'diff'		off	'scrollbind'	off	'scrollopt'	without "hor"	'wrap'		on	'foldmethod'	"manual"	'foldcolumn'	0 ==============================================================================2. Viewing diffs						*view-diffs* The effect is that the diff windows show the same text, with the differenceshighlighted.  When scrolling the text, the 'scrollbind' option will make thetext in other windows to be scrolled as well.  With vertical splits the textshould be aligned properly. The alignment of text will go wrong when:- 'wrap' is on, some lines will be wrapped and occupy two or more screen  lines- folds are open in one window but not another- 'scrollbind' is off- changes have been made to the text- "filler" is not present in 'diffopt', deleted/inserted lines makes the  alignment go wrong All the buffers edited in a window where the 'diff' option is set will join inthe diff.  This is also possible for hidden buffers.  They must have beenedited in a window first for this to be possible. 					*:DiffOrig* *diff-original-file*Since 'diff' is a window-local option, it's possible to view the same bufferin diff mode in one window and "normal" in another window.  It is alsopossible to view the changes you have made to a buffer since the file wasloaded.  Since Vim doesn't allow having two buffers for the same file, youneed another buffer.  This command is useful: >	 command DiffOrig vert new | set bt=nofile | r # | 0d_ | diffthis	 	\ | wincmd p | diffthis(this is in |vimrc_example.vim|).  Use ":DiffOrig" to see the differencesbetween the current buffer and the file it was loaded from. A buffer that is unloaded cannot be used for the diff.  But it does work forhidden buffers.  You can use ":hide" to close a window without unloading thebuffer.  If you don't want a buffer to remain used for the diff do ":setnodiff" before hiding it. 							*:diffu* *:diffupdate*:diffu[pdate]			Update the diff highlighting and folds. Vim attempts to keep the differences updated when you make changes to thetext.  This mostly takes care of inserted and deleted lines.  Changes within aline and more complicated changes do not cause the differences to be updated.To force the differences to be updated use: > 	:diffupdate  Vim will show filler lines for lines that are missing in one window but arepresent in another.  These lines were inserted in another file or deleted inthis file.  Removing "filler" from the 'diffopt' option will make Vim notdisplay these filler lines.  Folds are used to hide the text that wasn't changed.  See |folding| for allthe commands that can be used with folds. The context of lines above a difference that are not included in the fold canbe set with the 'diffopt' option.  For example, to set the context to threelines: > 	:set diffopt=filler,context:3  The diffs are highlighted with these groups: |hl-DiffAdd|	DiffAdd		Added (inserted) lines.  These lines exist in				this buffer but not in another.|hl-DiffChange|	DiffChange	Changed lines.|hl-DiffText|	DiffText	Changed text inside a Changed line.  Vim				finds the first character that is different,				and the last character that is different				(searching from the end of the line).  The				text in between is highlighted.  This means				that parts in the middle that are still the				same are highlighted anyway.  Only "iwhite" of				'diffopt' is used here.|hl-DiffDelete| DiffDelete	Deleted lines.  Also called filler lines,				because they don't really exist in this				buffer. ==============================================================================3. Jumping to diffs					*jumpto-diffs* Two commands can be used to jump to diffs:								*[c*	[c		Jump backwards to the previous start of a change.			When a count is used, do it that many times.								*]c*	]c		Jump forwards to the next start of a change.			When a count is used, do it that many times. It is an error if there is no change for the cursor to move to. ==============================================================================4. Diff copying			*copy-diffs* *E99* *E100* *E101* *E102* *E103*								*merge*There are two commands to copy text from one buffer to another.  The result isthat the buffers will be equal within the specified range. 							*:diffg* *:diffget*:[range]diffg[et] [bufspec]		Modify the current buffer to undo difference with another		buffer.  If [bufspec] is given, that buffer is used.		Otherwise this only works if there is one other buffer in diff		mode.		See below for [range]. 						*:diffpu* *:diffput* *E793*:[range]diffpu[t] [bufspec]		Modify another buffer to undo difference with the current		buffer.  Just like ":diffget" but the other buffer is modified		instead of the current one.		When [bufspec] is omitted and there is more than one other		buffer in diff mode where 'modifiable' is set this fails.		See below for [range]. 							*do*do		Same as ":diffget" without argument or range.  The "o" stands		for "obtain" ("dg" can't be used, it could be the start of		"dgg"!). 							*dp*dp		Same as ":diffput" without argument or range. When no [range] is given, the diff at the cursor position or just above it isaffected.  When [range] is used, Vim tries to only put or get the specifiedlines.  When there are deleted lines, this may not always be possible. There can be deleted lines below the last line of the buffer.  When the cursoris on the last line in the buffer and there is no diff above this line, the":diffget" and "do" commands will obtain lines from the other buffer. To be able to get those lines from another buffer in a [range] it's allowed touse the last line number plus one.  This command gets all diffs from the otherbuffer: > 	:1,$+1diffget Note that deleted lines are displayed, but not counted as text lines.  Youcan't move the cursor into them.  To fill the deleted lines with the linesfrom another buffer use ":diffget" on the line below them.								*E787*When the buffer that is about to be modified is read-only and the autocommandthat is triggered by |FileChangedRO| changes buffers the command will fail.The autocommand must not change buffers. The [bufspec] argument above can be a buffer number, a pattern for a buffername or a part of a buffer name.  Examples: 	:diffget		Use the other buffer which is in diff mode	:diffget 3		Use buffer 3	:diffget v2		Use the buffer which matches "v2" and is in				diff mode (e.g., "file.c.v2") ==============================================================================5. Diff options						*diff-options* Also see |'diffopt'| and the "diff" item of |'fillchars'|.  FINDING THE DIFFERENCES					*diff-diffexpr* The 'diffexpr' option can be set to use something else than the standard"diff" program to compare two files and find the differences. When 'diffexpr' is empty, Vim uses this command to find the differencesbetween file1 and file2: > 	diff file1 file2 > outfile The ">" is replaced with the value of 'shellredir'. The output of "diff" must be a normal "ed" style diff.  Do NOT use a contextdiff.  This example explains the format that Vim expects: > 	1a2	> bbb	4d4	< 111	7c7	< GGG	---	> ggg The "1a2" item appends the line "bbb".The "4d4" item deletes the line "111".The '7c7" item replaces the line "GGG" with "ggg". When 'diffexpr' is not empty, Vim evaluates to obtain a diff file in theformat mentioned.  These variables are set to the file names used: 	v:fname_in		original file	v:fname_new		new version of the same file	v:fname_out		resulting diff file Additionally, 'diffexpr' should take care of "icase" and "iwhite" in the'diffopt' option.  'diffexpr' cannot change the value of 'lines' and'columns'. Example (this does almost the same as 'diffexpr' being empty): > 	set diffexpr=MyDiff()	function MyDiff()	   let opt = ""	   if &diffopt =~ "icase"	     let opt = opt . "-i "	   endif	   if &diffopt =~ "iwhite"	     let opt = opt . "-b "	   endif	   silent execute "!diff -a --binary " . opt . v:fname_in . " " . v:fname_new .		\  " > " . v:fname_out	endfunction The "-a" argument is used to force comparing the files as text, comparing asbinaries isn't useful.  The "--binary" argument makes the files read in binarymode, so that a CTRL-Z doesn't end the text on DOS. 						*E97*Vim will do a test if the diff output looks alright.  If it doesn't, you willget an error message.  Possible causes:-  The "diff" program cannot be executed.-  The "diff" program doesn't produce normal "ed" style diffs (see above).-  The 'shell' and associated options are not set correctly.  Try if filtering   works with a command like ":!sort".-  You are using 'diffexpr' and it doesn't work.If it's not clear what the problem is set the 'verbose' option to one or moreto see more messages. The self-installing Vim includes a diff program.  If you don't have it youmight want to download a diff.exe.  For example fromhttp://jlb.twu.net/code/unixkit.php.  USING PATCHES					*diff-patchexpr* The 'patchexpr' option can be set to use something else than the standard"patch" program. When 'patchexpr' is empty, Vim will call the "patch" program like this: > 	patch -o outfile origfile < patchfile This should work fine with most versions of the "patch" program.  Note that aCR in the middle of a line may cause problems, it is seen as a line break. If the default doesn't work for you, set the 'patchexpr' to an expression thatwill have the same effect.  These variables are set to the file names used: 	v:fname_in		original file	v:fname_diff		patch file	v:fname_out		resulting patched file Example (this does the same as 'patchexpr' being empty): > 	set patchexpr=MyPatch()	function MyPatch()	   :call system("patch -o " . v:fname_out . " " . v:fname_in .	   \  " < " . v:fname_diff)	endfunction Make sure that using the "patch" program doesn't have unwanted side effects.For example, watch out for additionally generated files, which should bedeleted.  It should just patch the file and nothing else.   Vim will change directory to "/tmp" or another temp directory beforeevaluating 'patchexpr'.  This hopefully avoids that files in the currentdirectory are accidentally patched.  Vim will also delete files starting withv:fname_in and ending in ".rej" and ".orig".  vim:tw=78:ts=8:ft=help:norl: