git-rev-parse(1)
================

NAME
----
git-rev-parse - Pick out and massage parameters.


SYNOPSIS
--------
'git-rev-parse' [ --option ] <args>...

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

Many git Porcelainish commands take mixture of flags
(i.e. parameters that begin with a dash '-') and parameters
meant for underlying `git-rev-list` command they use internally
and flags and parameters for other commands they use as the
downstream of `git-rev-list`.  This command is used to
distinguish between them.


OPTIONS
-------
--revs-only::
	Do not output flags and parameters not meant for
	`git-rev-list` command.

--no-revs::
	Do not output flags and parameters meant for
	`git-rev-list` command.

--flags::
	Do not output non-flag parameters.

--no-flags::
	Do not output flag parameters.

--default <arg>::
	If there is no parameter given by the user, use `<arg>`
	instead.

--verify::
	The parameter given must be usable as a single, valid
	object name.  Otherwise barf and abort.

--sq::
	Usually the output is made one line per flag and
	parameter.  This option makes output a single line,
	properly quoted for consumption by shell.  Useful when
	you expect your parameter to contain whitespaces and
	newlines (e.g. when using pickaxe `-S` with
	`git-diff-\*`).

--not::
	When showing object names, prefix them with '{caret}' and
	strip '{caret}' prefix from the object names that already have
	one.

--symbolic::
	Usually the object names are output in SHA1 form (with
	possible '{caret}' prefix); this option makes them output in a
	form as close to the original input as possible.


--all::
	Show all refs found in `$GIT_DIR/refs`.

--show-prefix::
	When the command is invoked from a directory show the
	path of the current directory relative to the top-level
	directory.

--since=datestring, --after=datestring::
	Parses the date string, and outputs corresponding
	--max-age= parameter for git-rev-list command.

--until=datestring, --before=datestring::
	Parses the date string, and outputs corresponding
	--min-age= parameter for git-rev-list command.

<args>...::
	Flags and parameters to be parsed.


SPECIFYING REVISIONS
--------------------

A revision parameter typically, but not necessarily, names a
commit object.  They use what is called an 'extended SHA1'
syntax.

* The full SHA1 object name (40-byte hexadecimal string), or
  a substring of such that is unique within the repository.
  E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
  name the same commit object if there are no other object in
  your repository whose object name starts with dae86e.

* A symbolic ref name.  E.g. 'master' typically means the commit
  object referenced by $GIT_DIR/refs/heads/master.  If you
  happen to have both heads/master and tags/master, you can
  explicitly say 'heads/master' to tell git which one you mean.

* A suffix '{caret}' to a revision parameter means the first parent of
  that commit object.  '{caret}<n>' means the <n>th parent (i.e.
  'rev{caret}'
  is equivalent to 'rev{caret}1').  As a special rule,
  'rev{caret}0' means the commit itself and is used when 'rev' is the
  object name of a tag object that refers to a commit object.

* A suffix '~<n>' to a revision parameter means the commit
  object that is the <n>th generation grand-parent of the named
  commit object, following only the first parent.  I.e. rev~3 is
  equivalent to rev{caret}{caret}{caret} which is equivalent to\
  rev{caret}1{caret}1{caret}1.

* A suffix '{caret}' followed by an object type name enclosed in
  brace pair (e.g. `v0.99.8{caret}\{commit\}`) means the object
  could be a tag, and dereference the tag recursively until an
  object of that type is found or the object cannot be
  dereferenced anymore (in which case, barf).  `rev{caret}0`
  introduced earlier is a short-hand for `rev{caret}\{commit\}`.

* A suffix '{caret}' followed by an empty brace pair
  (e.g. `v0.99.8{caret}\{\}`) means the object could be a tag,
  and dereference the tag recursively until a non-tag object is
  found.

'git-rev-parse' also accepts a prefix '{caret}' to revision parameter,
which is passed to 'git-rev-list'.  Two revision parameters
concatenated with '..' is a short-hand for writing a range
between them.  I.e. 'r1..r2' is equivalent to saying '{caret}r1 r2'

Here is an illustration, by Jon Loeliger.  Both node B and C are
a commit parents of commit node A.  Parent commits are ordered
left-to-right.

    G   H   I   J
     \ /     \ /
      D   E   F
       \  |  /
        \ | /
         \|/
          B     C
           \   /
            \ /
             A

    A =      = A^0
    B = A^   = A^1     = A~1
    C = A^2  = A^2
    D = A^^  = A^1^1   = A~2
    E = B^2  = A^^2
    F = B^3  = A^^3
    G = A^^^ = A^1^1^1 = A~3
    H = D^2  = B^^2    = A^^^2  = A~2^2
    I = F^   = B^3^    = A^^3^
    J = F^2  = B^3^2   = A^^3^2


Author
------
Written by Linus Torvalds <torvalds@osdl.org> and
Junio C Hamano <junkio@cox.net>

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

GIT
---
Part of the gitlink:git[7] suite