merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

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+git-cat-file(1)
+===============
+
+NAME
+----
+git-cat-file - Provide content or type and size information for repository objects
+
+
+SYNOPSIS
+--------
+[verse]
+'git cat-file' (-t [--allow-unknown-type]| -s [--allow-unknown-type]| -e | -p | <type> | --textconv | --filters ) [--path=<path>] <object>
+'git cat-file' (--batch | --batch-check) [ --textconv | --filters ] [--follow-symlinks]
+
+DESCRIPTION
+-----------
+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.
+
+OPTIONS
+-------
+<object>::
+	The name of the object to show.
+	For a more complete list of ways to spell object names, see
+	the "SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
+
+-t::
+	Instead of the content, show the object type identified by
+	<object>.
+
+-s::
+	Instead of the content, show the object size identified by
+	<object>.
+
+-e::
+	Exit with zero status if <object> exists and is a valid
+	object. If <object> is of an invalid format exit with non-zero and
+	emits an error on stderr.
+
+-p::
+	Pretty-print the contents of <object> based on its type.
+
+<type>::
+	Typically this matches the real type of <object> but asking
+	for a type that can trivially be dereferenced from the given
+	<object> is also permitted.  An example is to ask for a
+	"tree" with <object> being a commit object that contains it,
+	or to ask for a "blob" with <object> being a tag object that
+	points at it.
+
+--textconv::
+	Show the content as transformed by a textconv filter. In this case,
+	<object> has to be of the form <tree-ish>:<path>, or :<path> in
+	order to apply the filter to the content recorded in the index at
+	<path>.
+
+--filters::
+	Show the content as converted by the filters configured in
+	the current working tree for the given <path> (i.e. smudge filters,
+	end-of-line conversion, etc). In this case, <object> has to be of
+	the form <tree-ish>:<path>, or :<path>.
+
+--path=<path>::
+	For use with --textconv or --filters, to allow specifying an object
+	name and a path separately, e.g. when it is difficult to figure out
+	the revision from which the blob came.
+
+--batch::
+--batch=<format>::
+	Print object information and contents for each object provided
+	on stdin.  May not be combined with any other options or arguments
+	except `--textconv` or `--filters`, in which case the input lines
+	also need to specify the path, separated by whitespace.  See the
+	section `BATCH OUTPUT` below for details.
+
+--batch-check::
+--batch-check=<format>::
+	Print object information for each object provided on stdin.  May
+	not be combined with any other options or arguments except
+	`--textconv` or `--filters`, in which case the input lines also
+	need to specify the path, separated by whitespace.  See the
+	section `BATCH OUTPUT` below for details.
+
+--batch-all-objects::
+	Instead of reading a list of objects on stdin, perform the
+	requested batch operation on all objects in the repository and
+	any alternate object stores (not just reachable objects).
+	Requires `--batch` or `--batch-check` be specified. Note that
+	the objects are visited in order sorted by their hashes.
+
+--buffer::
+	Normally batch output is flushed after each object is output, so
+	that a process can interactively read and write from
+	`cat-file`. With this option, the output uses normal stdio
+	buffering; this is much more efficient when invoking
+	`--batch-check` on a large number of objects.
+
+--unordered::
+	When `--batch-all-objects` is in use, visit objects in an
+	order which may be more efficient for accessing the object
+	contents than hash order. The exact details of the order are
+	unspecified, but if you do not require a specific order, this
+	should generally result in faster output, especially with
+	`--batch`.  Note that `cat-file` will still show each object
+	only once, even if it is stored multiple times in the
+	repository.
+
+--allow-unknown-type::
+	Allow -s or -t to query broken/corrupt objects of unknown type.
+
+--follow-symlinks::
+	With --batch or --batch-check, follow symlinks inside the
+	repository when requesting objects with extended SHA-1
+	expressions of the form tree-ish:path-in-tree.  Instead of
+	providing output about the link itself, provide output about
+	the linked-to object.  If a symlink points outside the
+	tree-ish (e.g. a link to /foo or a root-level link to ../foo),
+	the portion of the link which is outside the tree will be
+	printed.
++
+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
+--
+
+
+OUTPUT
+------
+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 <type> is specified, the raw (though uncompressed) contents of the <object>
+will be returned.
+
+BATCH OUTPUT
+------------
+
+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
+linkgit: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:
+
+`objectname`::
+	The 40-hex object name of the object.
+
+`objecttype`::
+	The type of the object (the same as `cat-file -t` reports).
+
+`objectsize`::
+	The size, in bytes, of the object (the same as `cat-file -s`
+	reports).
+
+`objectsize:disk`::
+	The size, in bytes, that the object takes up on disk. See the
+	note about on-disk sizes in the `CAVEATS` section below.
+
+`deltabase`::
+	If the object is stored as a delta on-disk, this expands to the
+	40-hex sha1 of the delta base object. Otherwise, expands to the
+	null sha1 (40 zeroes). See `CAVEATS` below.
+
+`rest`::
+	If this atom is used in the output string, input lines are split
+	at the first whitespace boundary. All characters before that
+	whitespace are considered to be the object name; characters
+	after that first run of whitespace (i.e., the "rest" of the
+	line) are output in place of the `%(rest)` atom.
+
+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
+------------
+is printed when, during symlink resolution, a file is used as a
+directory name.
+
+CAVEATS
+-------
+
+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.
+
+Note also that multiple copies of an object may be present in the object
+database; in this case, it is undefined which copy's size or delta base
+will be reported.
+
+GIT
+---
+Part of the linkgit:git[1] suite