git cat-file (-t [--allow-unknown-type]| -s [--allow-unknown-type]| -e | -p | <type> | --textconv | --filters ) [--path=<path>] <object> git cat-file (--batch[=<format>] | --batch-check[=<format>]) [ --textconv | --filters ] [--follow-symlinks]
In its first form, the command provides the content or the type of an object in the repository. The type is required unless -t or -p is used to find the object type, or -s is used to find the object size, or --textconv or --filters is used (which imply type "blob").
In the second form, a list of objects (separated by linefeeds) is provided on stdin, and the SHA-1, type, and size of each object is printed on stdout. The output format can be overridden using the optional <format> argument. If either --textconv or --filters was specified, the input is expected to list the object names followed by the path name, separated by a single whitespace, so that the appropriate drivers can be determined.
This option does not (currently) work correctly when an object in the index is specified (e.g. :link instead of HEAD:link) rather than one in the tree.
This option cannot (currently) be used unless --batch or --batch-check is used.
For example, consider a git repository containing:
f: a file containing "hello\n" link: a symlink to f dir/link: a symlink to ../f plink: a symlink to ../f alink: a symlink to /etc/passwd
For a regular file f, echo HEAD:f | git cat-file --batch would print
ce013625030ba8dba906f756967f9e9ca394464a blob 6
And echo HEAD:link | git cat-file --batch --follow-symlinks would print the same thing, as would HEAD:dir/link, as they both point at HEAD:f.
Without --follow-symlinks, these would print data about the symlink itself. In the case of HEAD:link, you would see
4d1ae35ba2c8ec712fa2a379db44ad639ca277bd blob 1
Both plink and alink point outside the tree, so they would respectively print:
symlink 4 ../f
symlink 11 /etc/passwd
If -t is specified, one of the <type>.
If -s is specified, the size of the <object> in bytes.
If -e is specified, no output, unless the <object> is malformed.
If -p is specified, the contents of <object> are pretty-printed.
If --batch or --batch-check is given, cat-file will read objects from stdin, one per line, and print information about them. By default, the whole line is considered as an object, as if it were fed to git-rev-parse(1).
You can specify the information shown for each object by using a custom <format>. The <format> is copied literally to stdout for each object, with placeholders of the form %(atom) expanded, followed by a newline. The available atoms are:
If no format is specified, the default format is %(objectname) %(objecttype) %(objectsize).
If --batch is specified, the object information is followed by the object contents (consisting of %(objectsize) bytes), followed by a newline.
For example, --batch without a custom format would produce:
<sha1> SP <type> SP <size> LF <contents> LF
Whereas --batch-check='%(objectname) %(objecttype)' would produce:
<sha1> SP <type> LF
If a name is specified on stdin that cannot be resolved to an object in the repository, then cat-file will ignore any custom format and print:
<object> SP missing LF
If a name is specified that might refer to more than one object (an ambiguous short sha), then cat-file will ignore any custom format and print:
<object> SP ambiguous LF
If --follow-symlinks is used, and a symlink in the repository points outside the repository, then cat-file will ignore any custom format and print:
symlink SP <size> LF <symlink> LF
The symlink will either be absolute (beginning with a /), or relative to the tree root. For instance, if dir/link points to ../../foo, then <symlink> will be ../foo. <size> is the size of the symlink in bytes.
If --follow-symlinks is used, the following error messages will be displayed:
<object> SP missing LF
is printed when the initial symlink requested does not exist.
dangling SP <size> LF <object> LF
is printed when the initial symlink exists, but something that it (transitive-of) points to does not.
loop SP <size> LF <object> LF
is printed for symlink loops (or any symlinks that require more than 40 link resolutions to resolve).
notdir SP <size> LF <object> LF
Note that the sizes of objects on disk are reported accurately, but care should be taken in drawing conclusions about which refs or objects are responsible for disk usage. The size of a packed non-delta object may be much larger than the size of objects which delta against it, but the choice of which object is the base and which is the delta is arbitrary and is subject to change during a repack.
Part of the git(1) suite