p4 diff2


Compare two depot file revisions.


p4 [g-opts] diff2 [-doptions] [-Od -q -t -u] file1[revfile2[rev]
p4 [g-opts] diff2 [-doptions] [-Od -q -t -u] -b branch [[fromfile[rev]] tofile[rev]]
p4 [g-opts] diff2 [-doptions] [-Od -q -t -u] -S stream [-P parent]
                  [[fromfile[rev]] tofile[rev]]


p4 diff2 uses the Perforce service's built-in diff routine to compare two file revisions from the depot. These revisions are usually two versions of the same file, but they can be revisions of entirely separate files. If no file revision is explicitly provided with the file argument, the head revision is used.

p4 diff2 does not use the diff program specified by the environment variable P4DIFF. The diff algorithm used by p4 diff2 runs on the machine hosting the shared Perforce service, and always uses the service's built-in diff routine.

You can specify file patterns as arguments in place of specific files, with or without revision specifiers; this causes Perforce to perform multiple diffs for each pair of files that match the given pattern. If you invoke p4 diff2 with file patterns, escape the file patterns from the OS shell by using quotes or backslashes, and be sure that the wildcards in the two file patterns match.

Perforce presents the diffs in UNIX diff format, prepended with a header. The header is formatted as follows:

==== file1 (filetype1) - file2 (filetype2) ==== summary

The possible values and meanings of summary are:

  • content: the file revisions' contents are different,

  • types: the revisions' contents are identical, but the filetypes are different,

  • identical: the revisions' contents and filetypes are identical.

If either file1 or file2 does not exist at the specified revision, the header displays the summary as <none>.


-b branch from[rev] to[rev]

Use a branch mapping to diff files in two branched codelines. The files that are compared can be limited by file patterns in either the from or to file specifications.


Runs the diff routine with one of a subset of the standard UNIX diff options. See Usage Notes for a listing of these options.


Limit output to only those files that differ.


Quiet diff. Display only the header; if file1 and file2 are identical, display only "file1 - no differing files" as the output.

-S stream [-P parent]

Diff a stream with its parent. To diff the stream with a stream other than its configured parent, specify -P.


Diff the file revisions even if the file(s) are not of type text.


Generate unified output format, showing added and deleted lines with sufficient context for compatibility with the patch(1) utility. Only those files that differ are included. File names and dates remain in Perforce syntax.


See “Global Options”.

Usage Notes

Can File Arguments Use Revision Specifier?

Can File Arguments Use Revision Range?

Minimal Access Level Required



read access necessary for both file revisions

  • The diff options supported by p4 diff2 are:




    RCS output format, showing additions and deletions made to the file and associated line ranges.


    context output format, showing line number ranges and num lines of context around the changes.


    summary output format, showing only the number of chunks and lines added, deleted, or changed.


    unified output format, showing added and deleted lines with num lines of context, in a form compatible with the patch(1) utility.


    ignore line-ending (CR/LF) convention when finding diffs


    ignore changes made within whitespace; this option implies -dl.


    ignore whitespace altogether; this option implies -dl.

  • To pass more than one option to the diff routine, group them together. For example:

    p4 diff2 -dub file1 file2

    specifies a unified diff that ignores changes in whitespace.

  • The header line of a unified diff produced with the -du option for patch(1) use displays the diffed files in Perforce syntax, not local syntax.

  • When p4 diff2 is used to diff binary files, the line

    ... files differ ...

    is printed if they are not identical.

  • The option -b branch [[fromfile[rev]] tofile[rev]] may seem incorrect at first. Because the branch mapping maps fromfiles to tofiles, why would you specify both fromfile and tofile file patterns? You wouldn't, but this syntax allows you to specify a fromfile file pattern and a tofile revision, or a fromfile revision and a tofile file pattern.

  • RCS keywords within files are not expanded with p4 diff2.


p4 diff2 -ds file#1 file

Compare the fist revision of file file to its head revision, and display a summary of what chunks were added to, deleted from, or changed within the file.

p4 diff2 file@34 file@1998/12/04

Diff the revision of file that was in the depot after changelist 34 was submitted against the revision in the depot at midnight on December 4, 1998.

p4 diff2 //depot/rel1/... //depot/rel2/...#4

Compare the head revisions of all files under //depot/rel1 to the fourth revision of all files under //depot/rel2.

p4 diff2 //depot/rel1/* //depot/rel2/...

Not allowed. The wildcards in each file pattern must match.

p4 diff2 -b branch2 //depot/rel2/...#2 @50

Compare the second revision of the files in //depot/rel2/... to the files branched from it by branch mapping branch2 at the revision they were at in changelist 50.

Related Commands

To compare a client workspace file to a depot file revision

p4 diff

To view the entire contents of a file

p4 print