Perforce 2009.2: Command Reference

p4 diff2

Synopsis

Compare two depot file revisions.

Syntax

p4 [g-opts] diff2 [-dflags -q -t -u] file1[rev] file2[rev]
p4 [g-opts] diff2 [-dflags -q -t -u] -b branch [[fromfile[rev]] tofile[rev]]

Description

p4 diff2 uses the Perforce server'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 Perforce server, and always uses the server'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 will display the summary as <none>.

Options

-q	Quiet diff. Display only the header, and don't even display that when the file revisions' contents and types are identical.
-dflags	Runs the diff routine with one of a subset of the standard UNIX diff flags. See the Usage Notes below for a listing of these flags.
-b branchname fromfile[rev] tofile[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 fromfile or tofile.
-t	Diff the file revisions even if the file(s) are not of type text.
-u	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.
g-opts	See the Global Options section.

Usage Notes

Can File Arguments Use Revision Specifier?	Can File Arguments Use Revision Range?	Minimal Access Level Required
Yes	No	read access necessary for both file revisions

•	The diff flags supported by p4 diff2 are:

Flag	Name
-dn	RCS output format, showing additions and deletions made to the file and associated line ranges.
-dc	context output format, showing line number ranges and three lines of context around the changes.
-ds	summary output format, showing only the number of chunks and lines added, deleted, or changed.
-du	unified output format, showing added and deleted lines with sufficient context for compatibility with the patch(1) utility.
-db	ignore changes made within whitespace
-dw	ignore whitespace altogether

•	To pass more than one flag 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. Since 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.

Examples

p4 diff2 -ds file#1 file	Compare the second 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