Add git-for-each-ref: helper for language bindings

[thirdparty/git.git] / Documentation / git-for-each-ref.txt

git-for-each-ref(1)
===================

NAME
----
git-for-each-ref - Output information on each ref

SYNOPSIS
--------
'git-for-each-ref' [--count=<count>]* [--shell|--perl|--python] [--sort=<key>]* [--format=<format>] [<pattern>]

DESCRIPTION
-----------

Iterate over all refs that match `<pattern>` and show them
according to the given `<format>`, after sorting them according
to the given set of `<key>`s.  If `<max>` is given, stop after
showing that many refs.  The interporated values in `<format>`
can optionally be quoted as string literals in the specified
host language.

OPTIONS
-------
<count>::
	By default the command shows all refs that match
	`<pattern>`.  This option makes it stop after showing
	that many refs.

<key>::
	A field name to sort on.  Prefix `-` to sort in
	descending order of the value.  When unspecified,
	`refname` is used.  More than one sort keys can be
	given.

<format>::
	A string that interpolates `%(fieldname)` from the
	object pointed at by a ref being shown.  If `fieldname`
	is prefixed with an asterisk (`*`) and the ref points
	at a tag object, the value for the field in the object
	tag refers is used.  When unspecified, defaults to
	`%(refname)`.

<pattern>::
	If given, the name of the ref is matched against this
	using fnmatch(3).  Refs that do not match the pattern
	are not shown.

--shell, --perl, --python::
	If given, strings that substitute `%(fieldname)`
	placeholders are quoted as string literals suitable for
	the specified host language.  This is meant to produce
	a scriptlet that can directly be `eval`ed.


FIELD NAMES
-----------

Various values from structured fields in referenced objects can
be used to interpolate into the resulting output, or as sort
keys.

For all objects, the following names can be used:

refname::
	The name of the ref (the part after $GIT_DIR/refs/).

objecttype::
	The type of the object (`blob`, `tree`, `commit`, `tag`).

objectsize::
	The size of the object (the same as `git-cat-file -s` reports).

objectname::
	The object name (aka SHA-1).

In addition to the above, for commit and tag objects, the header
field names (`tree`, `parent`, `object`, `type`, and `tag`) can
be used to specify the value in the header field.

Fields that have name-email-date tuple as its value (`author`,
`committer`, and `tagger`) can be suffixed with `name`, `email`,
and `date` to extract the named component.

The first line of the message in a commit and tag object is
`subject`, the remaining lines are `body`.  The whole message
is `contents`.

For sorting purposes, fields with numeric values sort in numeric
order (`objectsize`, `authordate`, `committerdate`, `taggerdate`).
All other fields are used to sort in their byte-value order.

In any case, a field name that refers to a field inapplicable to
the object referred by the ref does not cause an error.  It
returns an empty string instead.


EXAMPLES
--------

Show the most recent 3 tagged commits::

------------
#!/bin/sh

git-for-each-ref --count=3 --sort='-*authordate' \
--format='From: %(*authorname) %(*authoremail)
Subject: %(*subject)
Date: %(*authordate)
Ref: %(*refname)

%(*body)
' 'refs/tags'
------------

A bit more elaborate report on tags::
------------
#!/bin/sh

fmt='
	r=%(refname)
	t=%(*objecttype)
	T=${r#refs/tags/}

	o=%(*objectname)
	n=%(*authorname)
	e=%(*authoremail)
	s=%(*subject)
	d=%(*authordate)
	b=%(*body)

	kind=Tag
	if test "z$t" = z
	then
		# could be a lightweight tag
		t=%(objecttype)
		kind="Lightweight tag"
		o=%(objectname)
		n=%(authorname)
		e=%(authoremail)
		s=%(subject)
		d=%(authordate)
		b=%(body)
	fi
	echo "$kind $T points at a $t object $o"
	if test "z$t" = zcommit
	then
		echo "The commit was authored by $n $e
at $d, and titled

    $s

Its message reads as:
"
		echo "$b" | sed -e "s/^/    /"
		echo
	fi
'

eval=`git-for-each-ref -s --format="$fmt" \
	--sort='*objecttype' \
	--sort=-taggerdate \
	refs/tags`
eval "$eval"
------------