diff.txt For Vim version 9.1. Last change: 2025 Nov 09 VIM REFERENCE MANUAL by Bram Moolenaar diff vimdiff gvimdiff diff-mode This file describes the +diff feature: Showing differences between two to eight versions of the same file. The basics are explained in section 08.7 of the user manual. 1. Starting diff mode start-vimdiff 2. Viewing diffs view-diffs 3. Jumping to diffs jumpto-diffs 4. Copying diffs copy-diffs 5. Diff anchors diff-anchors 6. Diff options diff-options ============================================================================== 1. Starting diff mode start-vimdiff 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 differences between 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 will then append the file name of the first argument to the directory name to find the file. By default an internal diff library will be used. When 'diffopt' or 'diffexpr' has been set an external "diff" command will be used. This only works when such a diff program is available. Diffs are local to the current tab page tab-page. You can't see diffs with a window in another tab page. This does make it possible to have several diffs 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 like using the -O argument. This uses vertical splits. If you prefer horizontal splits add the -o argument: vimdiff -o file1 file2 [file3 [file4]] If you always prefer horizontal splits include "horizontal" in 'diffopt'. In each of the edited files these options are set: 'diff' on 'scrollbind' on 'cursorbind' on 'scrollopt' includes "hor" 'wrap' off, or leave as-is if 'diffopt' includes "followwrap" 'foldmethod' "diff" 'foldcolumn' value from 'diffopt', default is 2 These options are set local to the window. When editing another file they are reset to the global value. The options can still be overruled from a modeline when re-editing the file. However, 'foldmethod' and 'wrap' won't be set from a modeline when 'diff' is set. See :diffoff for an easy way to revert the options. The differences shown are actually the differences in the buffer. Thus if you make changes after loading a file, these will be included in the displayed diffs. You might have to do ":diffupdate" now and then, not all changes are immediately taken into account, especially when using an external diff command. In your .vimrc file you could do something special when Vim was started in diff 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 :diffs[plit] {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 :difft[his] Make the current window part of the diff windows. This sets the options like for "vimdiff". :diffp[atch] {patchfile} E816 :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. Using the "patch" command is not allowed in restricted-mode. 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 eight buffers with 'diff' set. Since the option values are remembered with the buffer, you can edit another file for a moment and come back to the same file and be in diff mode again. :diffo :diffoff :diffo[ff] Switch off diff mode for the current window. Resets related options also when 'diff' was not set. :diffo[ff]! Switch off diff mode for the current window and in all windows in the current tab page where 'diff' is set. Resetting related options only happens in a window that has 'diff' set, if the current window does not have 'diff' set then no options in it are changed. Hidden buffers are also removed from the list of diff'ed buffers. The :diffoff command resets the relevant options to the values they had when using :diffsplit, :diffpatch, :diffthis, or starting Vim in diff mode. When using :diffoff twice the last saved values are restored. Otherwise they are set to their default value: 'diff' off 'scrollbind' off 'cursorbind' off 'scrollopt' without "hor" 'wrap' on, or leave as-is if 'diffopt' includes "followwrap" 'foldmethod' "manual" 'foldcolumn' 0 'foldenable' will most-likely be reset to off. That is when 'foldmethod' is is restored to "manual". The folds themselves are not cleared but they should not show up, resetting 'foldenable' is the best way to do that. ============================================================================== 2. Viewing diffs view-diffs The effect is that the diff windows show the same text, with the differences highlighted. When scrolling the text, the 'scrollbind' option will make the text in other windows to be scrolled as well. With vertical splits the text should 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 in the diff. This is also possible for hidden buffers. They must have been edited in a window first for this to be possible. To get rid of the hidden buffers use :diffoff!. :DiffOrig diff-original-file Since 'diff' is a window-local option, it's possible to view the same buffer in diff mode in one