git/Documentation/git-symbolic-ref.txt
Junio C Hamano cd0a781c38 Documentation: do not blindly run 'cat' .git/HEAD, or echo into it.
Many places in the documentation we still talked about reading
what commit is recorded in .git/HEAD or writing the new head
information into it, both assuming .git/HEAD is a symlink.  That
is not necessarily so.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-11-15 01:31:04 -08:00

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git-symbolic-ref(1)
===================
NAME
----
git-symbolic-ref - read and modify symbolic refs
SYNOPSIS
--------
'git-symbolic-ref' <name> [<ref>]
DESCRIPTION
-----------
Given one argument, reads which branch head the given symbolic
ref refers to and outputs its path, relative to the `.git/`
directory. Typically you would give `HEAD` as the <name>
argument to see on which branch your working tree is on.
Give two arguments, create or update a symbolic ref <name> to
point at the given branch <ref>.
Traditionally, `.git/HEAD` is a symlink pointing at
`refs/heads/master`. When we want to switch to another branch,
we did `ln -sf refs/heads/newbranch .git/HEAD`, and when we want
to find out which branch we are on, we did `readlink .git/HEAD`.
This was fine, and internally that is what still happens by
default, but on platforms that do not have working symlinks,
or that do not have the `readlink(1)` command, this was a bit
cumbersome. On some platforms, `ln -sf` does not even work as
advertised (horrors).
A symbolic ref can be a regular file that stores a string that
begins with `ref: refs/`. For example, your `.git/HEAD` *can*
be a regular file whose contents is `ref: refs/heads/master`.
This can be used on a filesystem that does not support symbolic
links. Instead of doing `readlink .git/HEAD`, `git-symbolic-ref
HEAD` can be used to find out which branch we are on. To point
the HEAD to `newbranch`, instead of `ln -sf refs/heads/newbranch
.git/HEAD`, `git-symbolic-ref HEAD refs/heads/newbranch` can be
used.
Currently, .git/HEAD uses a regular file symbolic ref on Cygwin,
and everywhere else it is implemented as a symlink. This can be
changed at compilation time.
Author
------
Written by Junio C Hamano <junkio@cox.net>
GIT
---
Part of the gitlink:git[7] suite