Tag Archives: version control

git completion on MacOsX

For most of the day I work on a linux machine and I quite got used to having git completion feature for free. But as an occasional MacOsX user I felt quite bad not having the same functionality available. So yesterday I spent a couple of hours googling and playing until I finally got it all working on my MacBook.

Here’s a quick guide.

First of all, you need git-completion script. You can either get it from git source archive

#> curl http://kernel.org/pub/software/scm/git/git-1.7.1.tar.gz -O
#> tar -xzvf git-1.7.1.tar.gz
#> cp git-1.7.1/contrib/completion/git-completion.bash ~/git-completion.bash

or download it directly from github

#> curl http://github.com/git/git/raw/master/contrib/completion/git-completion.bash -O
#> cp git-completion.bash ~/git-completion.bash

Next, modify your ~/.bash_profile file by adding the following line to it:

source ~/git-completion.bash

Now restart you terminal and start using TAB key to autocomplete git commands!

But I didn’t stop there. When I enter a directory with a git repository I like to know which branch it is currently on. To achieve that all you need to do is to modify PS1 environment variable. Add the following line to  your ~/.bash_profile file:

PS1='\u@\h:\W $(__git_ps1 "(%s)")\$ '

Now restart you terminal and cd into a git repository.

sebmarek@proofek:~ $ cd ~/git/phpUnderControl
sebmarek@proofek:phpUnderControl (master)$

To make it even more visible I use bash colouring feature to highlight branch name in a colour of my choice. See bash prompt HOWTO for more details. That’s how my PS1 environment variable looks like:

PS1='\u@\h:\W \[\033[32m\]$(__git_ps1 "(%s)")\[\033[0m\]\$ '

and that’s the result:

sebmarek@proofek:~ $ cd ~/git/phpUnderControl
sebmarek@proofek:phpUnderControl (master)$

Happy giting!

Sharing your git repository

… or maybe not.

We’ve had this problem for some time and couldn’t really find a good solution for that. We wanted to have some repositories to be only writeable for selected users and even some repositories to be accessible for some users and completely invisible for the others.

First requirement seemed to be pretty simple as git access control is based on file permissions. So creating a repository only writeable for a selected group seemed to work… until somebody hasn’t committed a change which created a new object in .git directory which wasn’t group writable! The next person trying to change this object after was getting permission denied error like that:

#> git push origin master
Counting objects: 5, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 286 bytes, done.
Total 3 (delta 2), reused 0 (delta 0)
fatal: failed to write object
error: unpack failed: unpack-objects abnormal exit
To smarek@mygitserver.com:/home/smarek/git/myRepo.git
 ! [remote rejected] master -> master (n/a (unpacker error))
error: failed to push some refs to 'smarek@mygitserver.com:/home/smarek/git/myRepo.git'

Obviously git atomic commits did its trick and didn’t break the repository, but at the same time this issue prevented us pushing the changes to remote repository! We had tried different git hooks, but it didn’t work the way we wanted. So basically we ended up with a script that must have been run manually on git server when the issue was encountered.

if [ $# -lt 1 ]; then
    echo "Usage: $0 <repo>"
    exit 1
chown -R owner:group /path/to/repo/$1.git/objects
chmod -R g+w /path/to/repo/$1.git/objects

Until now. Friend of mine (thanks rodrigez) actually discovered a native git feature, that allows you to control access to a repository – core.sharedRepository. It accepts the following values:

  • umask (or false) – the default value. Git uses permissions reported by umask
  • group (or true) – makes the repository group-writable
  • all (or world or everybody) – same as group, but make the repository readable by all users
  • 0xxx: 0xxx is an octal number and each file will have mode 0xxx. 0xxx will override users umask value. 0640 will create a repository which is group-readable but not writable. 0660 is equivalent to group.

You can set that using either git config command if your repository already exists, or you want to make the default value either global or system wide:

#> git config core.sharedRepository group

or during brand new repository creation:

#> git init --shared=group

So for me setting core.sharedRepository to group solves my first issues, while removing all access to other users to all files in the repository and setting core.sharedRepository to 0770 will restrict access to the repository to only limited number of people.

Git Up and Get Going

I have used git for the first time about a year ago. We’ve been talking about abandoning CVS for quite a while and Subversion seemed to be the best choice at the time. Yes we’ve looked at different version control systems, we tried sample migrations and still we couldn’t make a decision. And CVS… it was a constant battle, continuos corruptions, old hardware, hours long merges, but  it worked, so the general response was – why to change something that works.

We needed a strong kick in our butt and fortunately there was a man that was brave enough to kick until it hurt (thanks Rys!). With management convinced we only needed to plan the migration, schedule the training and just start using it.

That was about a year ago. Now, we use it on a daily basis, and I can’t imagine how we could live without it before. Yes, it’s not as mature as Subversion, Windows tool are poor and far from ideal, but it definitely speeded up our development process. I remember all this scepticism at the time and I only bring it up now because in the past few weeks I have actually seen more and more developers and projects switching to git. I was really glad to see PHPUnit and phpUnderControl moving over to github. It makes contribution to these projects so much easier.

I think git is the future of the open source software and it makes its development so much easier and faster. So if you haven’t used it yet or you’re just simply afraid of it, please put your fears aside and git up and going!