git-diff-tree(1) Manual Page

NAME

git - diff-tree - Compares the content and mode of blobs found via two tree objects

SYNOPSIS

git-diff-tree [-p] [-r] [-z] [—stdin] [-B] [-M] [-R] [-C] [-O<orderfile>] [-S<string>] [—pickaxe-all] [-m] [-s] [-v] [-t] <tree-ish> <tree-ish> [<pattern>]*

DESCRIPTION

Compares the content and mode of the blobs found via two tree objects.

Note that "git-diff-tree" can use the tree encapsulated in a commit object.

OPTIONS

<tree-ish>
The id of a tree object.
<pattern>
If provided, the results are limited to a subset of files matching one of these prefix strings. ie file matches /^<pattern1>|<pattern2>|…/ Note that pattern does not provide any wildcard or regexp features.
-p
generate patch (see section on generating patches). For git-diff-tree, this flag implies -r as well.
-B
Break complete rewrite changes into pairs of delete and create.
-M
Detect renames.
-C
Detect copies as well as renames.
-R
Swap two input trees.
-S<string>
Look for differences that contains the change in <string>.
—pickaxe-all
When -S finds a change, show all the changes in that changeset, not just the files that contains the change in <string>.
-O<orderfile>
Output the patch in the order specified in the <orderfile>, which has one shell glob pattern per line.
-r
recurse
-t
show tree entry itself as well as subtrees. Implies -r.
-z
\0 line termination on output
—root
When —root is specified the initial commit will be showed as a big creation event. This is equivalent to a diff against the NULL tree.
—stdin
When —stdin is specified, the command does not take <tree-ish> arguments from the command line. Instead, it reads either one <commit> or a pair of <tree-ish> separated with a single space from its standard input.

When a single commit is given on one line of such input, it compares the commit with its parents. The following flags further affects its behaviour. This does not apply to the case where two <tree-ish> separated with a single space are given.

-m
By default, "git-diff-tree —stdin" does not show differences for merge commits. With this flag, it shows differences to that commit from all of its parents.
-s
By default, "git-diff-tree —stdin" shows differences, either in machine-readable form (without -p) or in patch form (with -p). This output can be supressed. It is only useful with -v flag.
-v
This flag causes "git-diff-tree —stdin" to also show the commit message before the differences.

Limiting Output

If you're only interested in differences in a subset of files, for example some architecture-specific files, you might do:

git-diff-tree -r <tree-ish> <tree-ish> arch/ia64 include/asm-ia64

and it will only show you what changed in those two directories.

Or if you are searching for what changed in just kernel/sched.c, just do

git-diff-tree -r <tree-ish> <tree-ish> kernel/sched.c

and it will ignore all differences to other files.

The pattern is always the prefix, and is matched exactly. There are no wildcards. Even stricter, it has to match complete path comonent. I.e. "foo" does not pick up foobar.h. "foo" does match foo/bar.h so it can be used to name subdirectories.

An example of normal usage is:

torvalds@ppc970:~/git> git-diff-tree 5319e4......
*100664->100664 blob    ac348b.......->a01513.......      git-fsck-cache.c

which tells you that the last commit changed just one file (it's from this one:

commit 3c6f7ca19ad4043e9e72fa94106f352897e651a8
tree 5319e4d609cdd282069cc4dce33c1db559539b03
parent b4e628ea30d5ab3606119d2ea5caeab141d38df7
author Linus Torvalds <torvalds@ppc970.osdl.org> Sat Apr 9 12:02:30 2005
committer Linus Torvalds <torvalds@ppc970.osdl.org> Sat Apr 9 12:02:30 2005
Make "git-fsck-cache" print out all the root commits it finds.
Once I do the reference tracking, I'll also make it print out all the
HEAD commits it finds, which is even more interesting.

in case you care).

Output format

The output format from "git-diff-cache", "git-diff-tree" and "git-diff-files" is very similar.

These commands all compare two sets of things; what are compared are different:

git-diff-cache <tree-ish>
compares the <tree-ish> and the files on the filesystem.
git-diff-cache —cached <tree-ish>
compares the <tree-ish> and the cache.
git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>…]
compares the trees named by the two arguments.
git-diff-files [<pattern>…]
compares the cache and the files on the filesystem.

An output line is formatted this way:

in-place edit :100644 100644 bcd1234… 0123456… M file0 copy-edit :100644 100644 abcd123… 1234567… C68 file1 file2 rename-edit :100644 100644 abcd123… 1234567… R86 file1 file3 create :000000 100644 0000000… 1234567… N file4 delete :100644 000000 1234567… 0000000… D file5 unmerged :000000 000000 0000000… 0000000… U file6

That is, from the left to the right:

 (1) a colon.
 (2) mode for "src"; 000000 if creation or unmerged.
 (3) a space.
 (4) mode for "dst"; 000000 if deletion or unmerged.
 (5) a space.
 (6) sha1 for "src"; 0{40} if creation or unmerged.
 (7) a space.
 (8) sha1 for "dst"; 0{40} if creation, unmerged or "look at work tree".
 (9) a space.
(10) status, followed by optional "score" number.
(11) a tab or a NUL when '-z' option is used.
(12) path for "src"
(13) a tab or a NUL when '-z' option is used; only exists for C or R.
(14) path for "dst"; only exists for C or R.
(15) an LF or a NUL when '-z' option is used, to terminate the record.

<sha1> is shown as all 0's if new is a file on the filesystem and it is out of sync with the cache. Example:

:100644 100644 5be4a4...... 000000...... M file.c

Generating patches with -p

When "git-diff-cache", "git-diff-tree", or "git-diff-files" are run with a -p option, they do not produce the output described above; instead they produce a patch file.

The patch generation can be customized at two levels. This customization also applies to "git-diff-helper".

  1. When the environment variable GIT_EXTERNAL_DIFF is not set, these commands internally invoke "diff" like this:

    diff -L a/<path> -L a/<path> -pu <old> <new>
    

    For added files, /dev/null is used for <old>. For removed files, /dev/null is used for <new>

    The "diff" formatting options can be customized via the environment variable GIT_DIFF_OPTS. For example, if you prefer context diff:

    GIT_DIFF_OPTS=-c git-diff-cache -p $(cat .git/HEAD)
    
  2. When the environment variable GIT_EXTERNAL_DIFF is set, the program named by it is called, instead of the diff invocation described above.

    For a path that is added, removed, or modified, GIT_EXTERNAL_DIFF is called with 7 parameters:

    path old-file old-hex old-mode new-file new-hex new-mode
    

    where:

    <old|new>-file are files GIT_EXTERNAL_DIFF can use to read the contents of <old|ne>,
    <old|new>-hex are the 40-hexdigit SHA1 hashes,
    <old|new>-mode are the octal representation of the file modes.

    The file parameters can point at the user's working file (e.g. new-file in "git-diff-files"), /dev/null (e.g. old-file when a new file is added), or a temporary file (e.g. old-file in the cache). GIT_EXTERNAL_DIFF should not worry about unlinking the temporary file --- it is removed when GIT_EXTERNAL_DIFF exits.

For a path that is unmerged, GIT_EXTERNAL_DIFF is called with 1 parameter, <path>.

Git specific extention to diff format

What -p option produces is slightly different from the traditional diff format.

(1) It is preceeded with a "git diff" header, that looks like
    this:
diff --git a/file1 b/file2
The a/ and b/ filenames are the same unless rename/copy is
involved.  Especially, even for a creation or a deletion,
/dev/null is _not_ used in place of a/ or b/ filename.
When rename/copy is involved, file1 and file2 shows the
name of the source file of the rename/copy and the name of
the file that rename/copy produces, respectively.
(2) It is followed by extended header lines that are one or
    more of:
old mode <mode>
new mode <mode>
deleted file mode <mode>
new file mode <mode>
copy from <path>
copy to <path>
rename from <path>
rename to <path>
similarity index <number>
dissimilarity index <number>

Author

Written by Linus Torvalds <torvalds@osdl.org>

Documentation

Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.

GIT

Part of the git(7) suite