NAME¶
Git::Repository::Tutorial - Control git from Perl using Git::Repository
VERSION¶
version 1.312
SYNOPSIS¶
use Git::Repository;
# do cool stuff with Git, using the following advice
HOW-TO¶
A Git::Repository object represents an actual Git repository, against which you
can
run commands.
Obtain a Git::Repository object from an existing repository¶
If your script is expected to run against a repository in the current directory
(like most Git commands), let Git::Repository handle the magic:
$r = Git::Repository->new();
If the repository has a working copy (work tree):
$r = Git::Repository->new( work_tree => $dir );
If the repository is a bare repository, or you prefer to provide the
.git
directory location:
$r = Git::Repository->new( git_dir => $gitdir );
If the work tree and the git directory are in unrelated locations, you can also
provide both:
$r = Git::Repository->new( work_tree => $dir, git_dir => $gitdir );
The constructor also accepts an option hash. The various options are detailed in
the manual page for Git::Repository::Command.
Run any git command¶
Git commands can be run against an existing Git::Repository object, or against
the class itself (in which case, git will try to deduce its context from the
current directory and the environment).
The pattern for running commands is always the same:
$r->run( $command => @arguments, \%options );
The $command and @arguments are identical to those you'd pass to the
"git" command-line tool. The options hash contains options, as
described in the manual page for Git::Repository::Command.
Create a new repository¶
Sometime, you'll need to create the Git repository from scratch:
# git version 1.6.5 and above
Git::Repository->run( init => $dir );
$r = Git::Repository->new( work_tree => $dir );
Any git older than 1.6.5 requires the command to be run in the work tree, so we
use the "cwd" option:
# git version 1.5.0.rc1 and above
Git::Repository->run( init => { cwd => $dir } );
$r = Git::Repository->new( work_tree => $dir );
# older git versions
Git::Repository->run( 'init-db' => { cwd => $dir } );
$r = Git::Repository->new( work_tree => $dir );
Note that the old "create()" method is obsolete (as of Git::Repository
1.18, from April 16, 2011) and has been removed (as of Git::Repository 1.301,
January 21, 2013).
Clone a repository¶
Cloning works the same way:
Git::Repository->run( clone => $url => $dir );
$r = Git::Repository->new( work_tree => $dir );
Run a simple command¶
When you don't really care about the output of the command, just call it:
$r->run( add => '.' );
$r->run( commit => '-m', 'my commit message' );
In case of an error or warning, Git::Repository will "croak()" or
"carp()" appropriately.
Properly quote options¶
It's common to work out the proper string of Git commands needed to achieve your
goal in the shell, before actually turning them into calls to
"Git::Repository->run".
Some options might require quoting, to properly get the arguments to Git through
the shell:
# shell
$ git log --since='Fri Jul 26 19:34:15 2013 +0200' --grep='report ticket'
Such quoting is of course not needed with Git::Repository:
$since = 'Fri Jul 26 19:34:15 2013 +0200';
$grep = 'report ticket';
my $cmd = $r->command( log => "--since=$since", "--grep=$grep" );
Silence warnings for some Git commands¶
Some Git porcelain commands provide additional information on
"STDERR". One typical example is "git checkout":
$ git checkout mybranch
Switched to branch 'mybranch'
The "run()" method of Git::Repository treats all output on
"STDERR" as a warning. Therefore, the following code:
$r->run( checkout => 'mybranch' );
will output a warning like this one:
Switched to branch 'mybranch' at myscript.pl line 10.
In such a case, you can use the "quiet" option to silence the warning
for a single command:
$r->run( checkout => 'mybranch', { quiet => 1 } );
To silence
all warnings, you can pass the "quiet" option during
the creation of the original repository object:
my $r = Git::Repository->new( { quiet => 1 } );
This is not recommended, as it might hide important information from you.
Process normal and error output¶
The "run()" command doesn't capture "STDERR": it only warns
(or dies) if something was printed on it. To be able to actually capture error
output, "command()" must be used.
my $cmd = $r->command( @cmd );
my @errput = $cmd->stderr->getlines();
$cmd->close;
"run()" also captures all output at once, which can lead to
unnecessary memory consumption when capturing the output of some really
verbose commands.
my $cmd = $r->command( log => '--pretty=oneline', '--all' );
my $log = $cmd->stdout;
while (<$log>) {
...;
}
$cmd->close;
Of course, as soon as one starts reading and writing to an external process'
communication handles, a risk of blocking exists.
Caveat emptor.
Use the "input" option:
my $commit = $r->run( 'commit-tree', $tree, '-p', $parent,
{ input => $message } );
Change the environment of a command¶
Use the "env" option:
$r->run(
'commit', '-m', 'log message',
{ env => {
GIT_COMMITTER_NAME => 'Git::Repository',
GIT_COMMITTER_EMAIL => 'book@cpan.org',
},
},
);
See Git::Repository::Command for other available options.
Ensure the output from Git commands is not localized¶
Since version 1.7.9, Git translates its most common interface messages into the
user's language if translations are available and the locale is appropriately
set.
This means that naively parsing the output "porcelain" commands might
fail if the program is unexpectedly run under an unexpected locale.
The easiest way to ensure your Git commands will be run in a
"locale-safe" environment, is to set the "LC_ALL"
environment variable to "C".
The brutal way:
$ENV{LC_ALL} = 'C';
The temporary way:
local $ENV{LC_ALL} = 'C';
The subtle way (restricted to the commands run on a given Git::Repository
instance):
my $r = Git::Repository->new( { env => { LC_ALL => 'C' } } );
The stealthiest way (restricted to a single command):
$r->run( ..., { env => { LC_ALL => 'C' } } );
Ensure the Git commands are run from the current working directory¶
By default, Git::Repository::Command will "chdir()" to the root of the
work tree before launching the requested Git command.
This means that no matter where your program "chdir()" to, commands on
the Git::Repository instance will by default be run from the root of the work
tree. So, commands such as "add" need to use the "full"
path (relative to "GIT_WORK_TREE") of the files to be added.
The "cwd" option can be used to define where Git::Repository::Command
will "chdir()" to. To instruct Git::Repository::Command to
not "chdir()" (and therefore run the Git command from the
current working directory), set the option to "undef":
# run from cwd for this command only
$r->run( ..., { cwd => undef } );
# always run git from cwd
my $r = Git::Repository->new( { cwd => undef } );
Finely control when "run()" dies¶
By default, "Git::Repository->run( ... )" dies if the Git command
exited with a status code of 128 (fatal error) or 129 (usage message).
Some commands will throw an error and exit with a status different from the
previous two:
$r->run( checkout => 'does-not-exist' ); # exit status: 1
The above "run()" call does not die, and output the following warning:
error: pathspec 'does-not-exist' did not match any file(s) known to git.
The exit status (as given by "$? >> 8") is 1.
To force "run()" to die when the Git command exits with status 1, use
the "fatal" option (added in version 1.304, May 25, 2013):
$r->run( checkout => 'does-not-exist', { fatal => 1 } );
By default, 128 and 129 remain in the list of fatal codes.
Here are a few examples:
# set the fatal codes for all call to run() on this object
$r = Git::Repository->new( { fatal => [ 1 .. 255 ] } );
As usual, setting the option to the Git::Repository object will set it for all
commands run for it:
# "!0" is a shortcut for 1 .. 255
$r = Git::Repository->new( { fatal => [ "!0" ] } );
Using negative codes will make these values non-fatal:
# the above call to new() makes all exit codes fatal
# but 3 and 7 won't be fatal for this specific run
$r->run( ..., { fatal => [ -3, -7 ] } );
When the list contains a single item, there is no need to use an array
reference:
# same as [ "!0" ]
$r = Git::Repository->new( { fatal => "!0" } );
# remove 17 from the list of fatal exit codes for this run only
$r->run( ..., { fatal => -17 } );
See Git::Repository::Command for other available options.
Process the output of git log¶
When creating a tool that needs to process the output of
git log, you
should always define precisely the expected format using the
--pretty
option, and choose a format that is easy to parse.
Assuming
git log will output the default format will eventually lead to
problems, for example when the user's git configuration defines
"format.pretty" to be something else than the default of
"medium".
See also Git::Repository::Plugin::Log for adding to your Git::Repository objects
a "log()" method that will parse the log output for you.
Process the output of git shortlog¶
git shortlog behaves differently when it detects it's not attached to a
terminal. In that case, it just tries to read some
git log output from
its standard input.
So this oneliner will hang, because
git shortlog is waiting for some data
from the program connected to its standard input (the oneliner):
perl -MGit::Repository -le 'print scalar Git::Repository->run( shortlog => -5 )'
Whereas this one will "work" (as in "immediately return with no
output"):
perl -MGit::Repository -le 'print scalar Git::Repository->run( shortlog => -5, { input => "" } )'
So, you need to give
git shortlog some input (from
git
log):
perl -MGit::Repository -le 'print scalar Git::Repository->run( shortlog => { input => scalar Git::Repository->run( log => -5 ) } )'
If the log output is large, you'll probably be better off with something like
the following:
use Git::Repository;
# start both git commands
my $log = Git::Repository->command('log')->stdout;
my $cmd = Git::Repository->command( shortlog => -ens );
# feed one with the output of the other
my $in = $cmd->stdin;
print {$in} $_ while <$log>;
close $in;
# and do something with the output
print $cmd->stdout->getlines;
Wrap git in a sudo call¶
If for a given repository you want to wrap all calls to git in a
"sudo" call, you can use the "git" option with an array
ref:
my $r = Git::Repository->new( { git => [qw( sudo -u nobody git )] } );
In this case, every call to git from $r will actually call "sudo -u nobody
git".
Use submodules¶
Because Git::Repository automatically sets the "GIT_DIR" and
"GIT_WORK_TREE" environment variables, some "submodule"
sub-commands may fail. For example:
$r->run( submodule => add => $repository => 'sub' );
will give the following error:
error: pathspec 'sub' did not match any file(s) known to git.
To avoid this error, you should enforce the removal of the
"GIT_WORK_TREE" variable from the environment in which the command
is run:
$r->run(
submodule => add => $repository => 'sub',
{ env => { GIT_WORK_TREE => undef } }
);
Note that System::Command version 1.04 is required to be able to remove
variables from the environment.
Sort git versions¶
Basically, you need to recreate the "cmp" operator for Git versions,
using the
private "_version_gt()" method (which accepts two
parameters):
@sorted_versions = sort {
Git::Repository::_version_gt( $a, $b )
|| -Git::Repository::_version_gt( $b, $a )
} @versions;
Add specialized methods to your Git::Repository objects¶
Have a look at Git::Repository::Plugin and Git::Repository::Plugin::Log, to
learn how to add your own methods to Git::Repository.
BUGS¶
Please report any bugs or feature requests on the bugtracker website
http://rt.cpan.org/NoAuth/Bugs.html?Dist=Git-Repository or by email to
bug-git-repository@rt.cpan.org.
When submitting a bug or request, please include a test-file or a patch to an
existing test-file that illustrates the bug or desired feature.
AUTHOR¶
Philippe Bruhat (BooK) <book@cpan.org>
COPYRIGHT¶
Copyright 2010-2014 Philippe Bruhat (BooK), all rights reserved.
LICENSE¶
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.