The [[mw:Git (software)|Git ]] system (http://git-scm.com/) was originally developed by Linus Torvalds as a distributed version control system to replace '''BitKeeper ''' for the Linux Kernel project The bottom line is this: modern software development may take many "forms", but it usually boils down to [http://nvie.com/posts/a-successful-git-branching-model/ this]. Git enables such a branched workflow. That is why distributed version control in general, and git in particular, is the most widely adopted version control system for software development <ref>https://ianskerrett.wordpress.com/2014/06/23/eclipse-community-survey-2014-results/</ref> See [[Git/hacks]] for example commands
== Intro to Git ==
The IIC has a new Greg Rundlett setup git repository hosting service.<br />You can browse our git repositories services at the IIC (http://svn.iic.harvard.edu/gitweb/)
Why do we have git? Because [http://whygitisbetterthanx.com Git is better than X] Now that we have the "My DVCS is better than your DVCS" argument out of the way, you can actually get some valuable insights from that website if you are interested in comparing Git with Mercurial, Bazaar, Subversion or Perforce. If I had to single out one primary advantage of Git, it would be that it actually features branching and merging.
Repo visibility is completely customizable, as are individual permissions to write to repos. I've installed a system called gitosis to handle the privileges through a special git repository. It uses Public Key cryptography rather than granting SSH accounts to everyone. This makes it really easy to do your work securely without even needing a password. For the curious, the actual mechanics of gitosis are detailed at [http://scie.nti.st/2007/11/14/hosting-git-repositories-the-easy-and-secure-way scie.nti.st]. Although that link may still work, there is also https://git-scm.com/book/en/v1/Git-on-the-Server-Gitosis.
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To host a public repo, go to http://github.com
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You might want to read about how we [[Git/migrating to git|migrate from Subversion to Git]] or how [http://julienrenaux.fr/2014/02/28/leading-the-svn-to-git-migration/ others have done it]
== Initial Configuration ==
In your [https://git-scm.com/book/en/v2/Getting-Started-First-Time-Git-Setup first time setting up Git on a new computer], you want to configure your username and email among other settings.
<source lang="bash">
git config --global user.name "Greg Rundlett"
git config --global user.email greg@freephile.com
git config --global core.editor vim
git config --global diff.tool meld
git config --global --add color.ui true
# store password in memory for an hour
git config --global credential.helper 'cache --timeout=3600'
# recent packaged versions of git might be 1.8.3.1 (CentOS 7.4) whereas the current available is 2.15.1
# push.default is unset; its implicit value is changing in
# Git 2.0 from 'matching' to 'simple'. To squelch this message
# and adopt the new behavior now, use:
git config --global push.default simple
</source>
=== Example .gitconfig ===
<code>git config --global -e</code> and paste in the following:
<source lang="ini">
[user]
name = Greg Rundlett
email = greg@freephile.com
[alias]
co = checkout
ci = commit
unstage = reset HEAD
wu = log --stat origin..@{0}
wup = log -p origin..@{0}
lg = log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit --date=relative
[core]
excludesfile = /home/greg/.gitignore_global
editor = vim
[color]
ui = true
[credential]
helper = cache --timeout=3600
# ------------------ M E R G E -------------------------
[merge]
tool = meld
[mergetool "meld"]
cmd = meld --auto-merge \"$LOCAL\" \"$BASE\" \"$REMOTE\" --output \"$MERGED\" --label \"MERGE (REMOTE BASE MY)\"
trustExitCode = false
[mergetool]
# don't ask if we want to skip merge
prompt = false
# don't create backup *.orig files
keepBackup = false
# ------------------ D I F F -------------------------
[diff]
guitool = meld
[difftool "meld"]
cmd = meld \"$LOCAL\" \"$REMOTE\" --label \"DIFF (Original v. Mine)\"
[push]
default = simple
[gitreview]
remote = origin
[help]
format = web
[web]
# browser = google-chrome
browser = firefox
</source>
{{Highlight
|text = If you want to browse the git help in your browser (as above), then make sure you <code>sudo apt-get install git-doc</code> to get the HTML files}}
== Decentralized Workflow and Branching Model ==
Here's a good explanation on how most groups use Git in a successful branching model for development, "master", release branches, hotfixes, etc.
http://nvie.com/posts/a-successful-git-branching-model/
== Submodules ==
Using multiple repositories to compose your project. See https://git-scm.com/book/en/v2/Git-Tools-Submodules
<source lang="bash">
git init myproject
cd myproject
git submodule add git@github.com:example.com/htdocs.git website
git submodule add https://gerrit.wikimedia.org/r/p/mediawiki/core.git mediawiki
git submodule add https://gitlab.com/Aranad/tools.git odtools
cd mediawiki/
git checkout REL1_31
cd ../
git commit -m 'initial commit'
git diff --submodule
git config --global diff.submodule log
git diff
git config -f .gitmodules submodule.mediawiki.branch REL1_31
git submodule update --remote
git status
git commit -am 'tracking REL1_31 in the mediawiki submodule'
git config status.submodulesummary 1
git log -p --submodule
cd mediawiki/
git submodule update --remote --merge
git config alias.sdiff '!'"git diff && git submodule foreach 'git diff'"
git config alias.spush 'push --recurse-submodules=on-demand'
git config alias.supdate 'submodule update --remote --merge'
</source>
== Tools ==
[[File:Meza.big.picture.pdf|thumb|Meza Big Picture|right]]
* http://git-scm.com/tools
* http://github.com/guides/using-the-egit-eclipse-plugin-with-github
* [https://github.com/esc/git-big-picture Git Big Picture] is a nice visualization tool that produces images like the one on the right.
== Reporting ==
How many lines have I contributed since last year?
<source lang="bash">
git log --stat --author $(git config --get user.email) --since="last year" --until="last month" | awk -F',' '/files? changed/ {
files += $1
insertions += $2
deletions += $3
print
}
END {
print "Files Changed: " files
print "Insertions: " insertions
print "Deletions: " deletions
print "Lines changed: " insertions + deletions
}'
</source>
== Visualizing ==
There are a lot of ways to use the <code>git log</code> command to visualize your history. Everything from <code>git log --pretty=oneline</code> or <code>git log --graph --oneline</code> to <code>git log --graph --full-history --all --color --date=short --pretty=format:"%x1b[31m%h%x09%x1b[32m%d%x1b[0m%x20%ad %s"</code> which you probably want to put into your <code>~/.gitconfig</code> as some alias because who the heck is going to remember that one?<ref>https://stackoverflow.com/questions/1838873/visualizing-branch-topology-in-git</ref> Of course there are also many GUI clients.
== Documentation ==
* http://wildlyinaccurate.com/a-hackers-guide-to-git Helpful intro because it doesn't pretend that Git is just like Subversion
* http://www.gitcasts.com GitCasts
* http://www.kernel.org/pub/software/scm/git/docs/everyday.html Everyday Git in 20 commands
* http://git.or.cz/course/svn.html
* http://software.complete.org/software/wiki/site/GitGuide Git Guide (short) at Software Complete.org
* '''http://book.git-scm.com/index.htmlbook/en/v2'''
* http://git-scm.com/documentation
* http://www.kernel.org/pub/software/scm/git/docs/user-manual.html
* http://github.com/guides/providing-your-ssh-key
== Now what? = Git and Subversion ===* http://git-scm.com/book/en/Git-and-Other-Systems-Git-and-Subversion* http://viget.com/extend/effectively-using-git-with-subversion* http://trac.parrot.org/parrot/wiki/git-svn-tutorial* http://flavio.castelli.name/2007/09/04/howto_use_git_with_svn/ == Background ==
I got into Git to make managing Drupal projects possible. Now that we have a distributed VCS, we can actually collaborate in multiple ways (more than just a centralized model<ref>http://whygitisbetterthanx.com/#any-workflow</ref>), and we can work offline . We can easily branch and merge. We can pull in updates from the Drupal core maintainers. We can pull in updates from the Drupal community (module maintainers). We can track our own custom modules - especially if they are developed by more than one person. We can branch, tag and deploy these combined sources to multiple instances (dev, staging, production) across multiple instances of Drupal (e.g. client projects that should share the exact same codebase) and have complete clarity on where each project stands regarding patches and security fixes or updates. There have been several attempts in the Drupal community (credit to Moshe, Ben,<ref>http://drupal.org/node/197666</ref> Dries, et al.<ref>http://drupal.org/node/355154</ref>) to get this all working over the past year or so and I think we're finally seeing the tide turn in our favor. Drupal may actually start to be "easy" to maintain and deploy. Actually, the whole point is to BE up-to-date on all our projects. This only happens when it is feasible. Git makes it feasible.
* http://versioncontrolblog.com/2007/08/02/upgrading-drupal-52-with-git/
I pulled down the whole clone (which is only 26MB in size) of mikl's public history of Drupal in a few minutes.
With Git , it is even possible to manage projects which are composites of multiple sources <ref>http://git.or.cz/gitwiki/GitSubmoduleTutorial</ref> (Ever tried that with Subversion's 'externals'? -- Don't bother to try it with Subversion because it just doesn't work! Not only are externals feature poor, you'll still end up wanting to merge even more than before. And as we know, merging is not a feature in Subversion.)
Only in /var/www/drupal/sites: www.example.org
</pre>
== How it was done Git Repo Hosting ==See [[Git repo hosting]] == Building a Git server == (This recipe was from 2008. It may still work, but ymmv)
Generally following the series of instructions at
http://vafer.org/blog/20080115011413 I installed Git-core, gitweb and gitosis on the host
<presource lang="bash">
# install git, the git-svn tool and the viewvc equivalent
apt-get install git-core git-svn gitweb
# and install it
apt-get install gitosis
</pre> == References ==<references /source>
* http://www.davidgrant.ca/maintaining_vendor_sources_with_subversion
* http://www.burtonini.com/blog/computers/svn-vendor-2005-05-04-13-55
{{References}}
[[Category:Tools]]
[[Category:Howto]]
[[Category:Subversion]]
[[Category:SystemAdministrationSystem Administration]]