In a Unix or GNU scripting environment (e.g. a Linux distro, Cygwin, OSX), what is the best way to determine which Git branch is currently checked out in a working directory?
One use of this technique would be automatically labeling a release (like svnversion would do with Subversion).
Please also see my related question: How to programmatically determine whether a Git checkout is a tag, and if so what is the tag name?
The correct solution is to take a peek at contrib/completions/git-completion.bash does that for bash prompt in __git_ps1. Removing all extras like selecting how to describe detached HEAD situation, i.e. when we are on unnamed branch, it is:
branch_name="$(git symbolic-ref HEAD 2>/dev/null)" ||
branch_name="(unnamed branch)" # detached HEAD
branch_name=${branch_name##refs/heads/}
git symbolic-ref is used to extract fully qualified branch name from symbolic reference; we use it for HEAD, which is currently checked out branch.
Alternate solution could be:
branch_name=$(git symbolic-ref -q HEAD)
branch_name=${branch_name##refs/heads/}
branch_name=${branch_name:-HEAD}
where in last line we deal with the detached HEAD situation, using simply "HEAD" to denote such situation.
Added 11-06-2013
Junio C. Hamano (git maintainer) blog post, Checking the current branch programatically, from June 10, 2013 explains whys (and hows) in more detail.
Does anyone see anything wrong with just asking Git to describe the branch you are on?
git rev-parse --symbolic-full-name --abbrev-ref HEAD
That can be used within $() and passed easily in Bash, Powershell, Perl, etc. It isn't fooled if you have several branches on the commit you are on, and if you currently aren't on a branch, it simply replies with "HEAD".
Alternatively, you can use
git symbolic-ref --short -q HEAD
Which will give you the same output, but it won't return anything at all if you are detached. This one is useful if you want an error when detached though, just remove the -q.
From this answer: https://stackoverflow.com/a/1418022/605356 :
$ git rev-parse --abbrev-ref HEAD
master
Apparently works with Git 1.6.3 or newer.
Try with:
git symbolic-ref --short -q HEAD
Or you try with git branch with --no-color force simple plain string the output:
git branch --no-color
With grep in regex mode(-E) you can check if exists the character '*':
git branch --no-color | grep -E '^\*'
The results its similar to:
* currentBranch
You can use the next options:
sed 's/\*[^a-z]*//g'
cut -d ' ' -f 2
awk '{print $2}'
for example:
git branch --no-color | grep -E '^\*' | sed 's/\*[^a-z]*//g'
git branch --no-color | grep -E '^\*' | sed cut -d ' ' -f 2
git branch --no-color | grep -E '^\*' | awk '{print $2}'
if exists a error you cant use an default value:
cmd || echo 'defualt value';
All into in a bash function:
function get_branch() {
git branch --no-color | grep -E '^\*' | awk '{print $2}' \
|| echo "default_value"
# or
# git symbolic-ref --short -q HEAD || echo "default_value";
}
branch_name=`get_branch`;
echo $branch_name;
Using --porcelain gives a backwards-compatible output easy to parse:
git status --branch --porcelain | grep '##' | cut -c 4-
From the documentation:
The porcelain format is similar to the short format, but is guaranteed not to change in a backwards-incompatible way between Git versions or based on user configuration. This makes it ideal for parsing by scripts.
Here's my solution, suitable for use in a PS1, or for automatically labeling a release
If you are checked out at a branch, you get the branch name.
If you are in a just init'd git project, you just get '@'
If you are headless, you get a nice human name relative to some branch or tag, with an '@' preceding the name.
If you are headless and not an ancestor of some branch or tag you just get the short SHA1.
function we_are_in_git_work_tree {
git rev-parse --is-inside-work-tree &> /dev/null
}
function parse_git_branch {
if we_are_in_git_work_tree
then
local BR=$(git rev-parse --symbolic-full-name --abbrev-ref HEAD 2> /dev/null)
if [ "$BR" == HEAD ]
then
local NM=$(git name-rev --name-only HEAD 2> /dev/null)
if [ "$NM" != undefined ]
then echo -n "@$NM"
else git rev-parse --short HEAD 2> /dev/null
fi
else
echo -n $BR
fi
fi
}
You can remove the if we_are_in_git_work_tree bit if you like; I just use it in another function in my PS1 which you can view in full here: PS1 line with git current branch and colors
If you are using gradle,
```
def gitHash = new ByteArrayOutputStream()
project.exec {
commandLine 'git', 'rev-parse', '--short', 'HEAD'
standardOutput = gitHash
}
def gitBranch = new ByteArrayOutputStream()
project.exec {
def gitCmd = "git symbolic-ref --short -q HEAD || git branch -rq --contains "+getGitHash()+" | sed -e '2,\$d' -e 's/\\(.*\\)\\/\\(.*\\)\$/\\2/' || echo 'master'"
commandLine "bash", "-c", "${gitCmd}"
standardOutput = gitBranch
}
```
That's one solution. If you add it to your .bashrc, it'll display the current branch in the console.
# git branch
parse_git_branch() {
git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/(\1) /'
}
$PS1="\$(parse_git_branch)$PS1"
However it's pretty limited. But there is a great project called git sh, which is doing exactly that (and much more).
I found that calling git is rather slow (any of the subcommands), especially for updating the prompt. Time varies between .1 and .2 seconds within the root dir of a repo, and over .2 seconds outside a repo, on a top notch machine (raid 1, 8 gb ram, 8 hardware threads). It does run Cygwin, though.
Therefore I wrote this script for speed:
#!/usr/bin/perl
$cwd=$ENV{PWD}; #`pwd`;
chomp $cwd;
while (length $cwd)
{
-d "$cwd/.git" and do {
-f "$cwd/.git/HEAD" and do {
open IN, "<", "$cwd/.git/HEAD";
$_=<IN>;
close IN;
s@ref: refs/heads/@@;
print $_;
};
exit;
};
$cwd=~s@/[^/]*$@@;
}
May need some tweaking.
If you are on a detached head (i.e. you've checked out a release) and have an output from git status such as
HEAD detached at v1.7.3.1
And you want the release version, we use the following command...
git status --branch | head -n1 | tr -d 'A-Za-z: '
This returns 1.7.3.1, which we replace in our parameters.yml (Symfony) with
# RevNum=`svn status -u | grep revision | tr -d 'A-Za-z: '` # the old SVN version
RevNum=`git status --branch | head -n1 | tr -d 'A-Za-z: '` # Git (obvs)
sed -i "/^ app_version:/c\ app_version:$RevNum" app/config/parameters.yml
Hope this helps :) Obviously if you have non-numerics in your branch name, you'll need to alter the arguments to the tr command.
git branch --show-current. See my answer here. – VonC