Difference between revisions of "Super Quick Git Guide"

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(ancient (~2009) guide to git, duplicates main article and better guides are available anyway)
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[[Category:Package development]]
#REDIRECT: [[Git]]
{{Merge|Git|This guide doesn't seem any "quicker" than [[Git#Basic usage]], and instead it's making readers' lives harder because they have two articles to follow and compare. Maybe this article could really be turned into a "quick" git guide, but the internet is already chock-full of git cheatsheets, adding another one wouldn't make much sense.|section=Title consideration}}
{{Related articles start}}
{{Related articles end}}
This isn't meant to be an all-encompassing guide by any means - it is meant to
be a really quick walk-through on how to do some basic operations on a git project, such as submitting a patch, taking [https://projects.archlinux.org/pacman.git/ pacman.git] as an example.
For more extensive tutorials, check out the following:
*http://wiki.winehq.org/GitWine (talks a lot about maintaining patches)
In addition, all git commands have decent manpages to refer to. They can be
reached one of two ways - for the git-add command, type 'man git-add' or
'git help add'.
==Getting started==
The first step with git is cloning a remote repository. This is known in the
CVS and SVN camps as checking out. GIT checkout has a different purpose, but
that will be covered later.
To grab the pacman source into a new directory named 'pacman', run the following:
<nowiki>$ git clone git://projects.archlinux.org/pacman.git pacman</nowiki>
This will check out a local copy of the repository for you. This means you have
the FULL history of the project on your computer, not just the most recent
revision. This allows you to get work done even when offline, for example.
The first steps after cloning may be just to look around. If you have read the
tutorials mentioned above, even if you do not understand everything in them,
you will be much better off.
You will probably want to set up your name and email address for use in commit
git config user.name "Your Name"
git config user.email "me@example.com"
or use global settings that can be used by other applications:
# chfn -f 'Your Name' user
$ export EMAIL='me@example.com'
If you pass the '--global' flag to the above git commands, the name and email will
be stored in ~/.gitconfig, so will be used for all git projects unless
overridden by a setting in the individual project.
To update your local repository with any new branches, run 'git pull'.
==Next steps==
===Git branches===
'git branch' will show you a list of branches. Initially, master is the only
branch. However, if you pulled from a remote repo, you may have grabbed other
branches- these can be seen with 'git branch -r'. Read the manpage for details.
When working with git, it is good practice to never do your work on the master
branch. This should stay clean to allow you to run 'git pull' and ensure that
conflicts do not happen on the update.
To create your own working branch, do the following (naming it whatever your
heart desires):
git branch working
git checkout working
Or compress the above into one command:
git checkout -b working
To switch back to the master branch use:
git checkout master
but you can only leave a branch if there are no pending changes to commit.  Find
out what changes have not been committed using:
$ git status
# On branch working
# Changed but not updated:
#  (use "git add <file>..." to update what will be committed)
# modified:  lib/libalpm/util.c
no changes added to commit (use "git add" and/or "git commit -a")
Either commit the changes or revert them before switching branches.
I highly recommend you read the man page for these commands.
===Adding a remote repository===
Each developer usually has his own repository, it might be interesting to have them all available locally.
For example:
<nowiki>git remote add toofishes http://code.toofishes.net/gitprojects/pacman.git</nowiki>
You can see all available branches with 'git branch -r', and as above, create your own based on one of these remote branches:
git checkout -b toofishes-working toofishes/working
===Other time savers===
If you use CVS or SVN and are used to 'co' being equivalent to 'checkout', try the following:
git config --global alias.co "checkout"
You can set any other aliases you like. For example:
git config --global alias.chp "cherry-pick"
git config --global alias.b "branch"
git config --global alias.rf "checkout HEAD"
'git status' is highly helpful, it is recommended to read up on that.
==Making a patch==
Woo! You found a bug in pacman (what a surprise) and know how to fix it. Ensure
you have your working branch checked out ('git checkout working'). Then edit
the file(s) you need in order to make your changes. Compiling is a good idea
to ensure your patch didn't break anything, and if it is a big change, running
'make check' is highly recommended.
So what do you do now? First, run 'git status'. You should see a list or even a
few lists of files. The descriptions by each are a bit confusing, but you
should be able to figure it out. GIT takes a different approach than CVS or SVN
to committing changes- it doesn't commit a thing by default. You have to tell
it what to commit, usually by running 'git add <filename>'. At this point, the
file in its current state will be sent to a staging area for the commit. If
you go back and change something in the file, you will have to git-add it again
if you want the changes to be reflected in the commit.
To commit your patch to your branch:
git add <all edited files>
git commit -s
or just:
git commit -sa
You will then be prompted for a commit message. When writing the message, keep the following in mind. The first line is
used as a patch summary- keep it short and concise. Next, skip a line and type
out a full description of what your patch does. By full, I do not mean long- if
you described everything in the summary line, then do not even bother with a
message. Finally, skip one more line and you will have your Signed-off-by.
This should have been automatically added by passing the '-s' parameter to
'git commit'.
There is one more important step before submission. Because git is distributed,
you do not have the most current version of the repository unless you go out and
get it. In the easiest case, this is just running 'git pull' on the master branch.
git checkout master
git pull
You also want to make sure your patches are based off the most recent revision,
known as the 'head'. To do this, checkout your branch with your patches, and
use the following command:
git checkout my-branch
git rebase master
To visualize what the above command did, qgit can be very helpful.
To format a patch for email submission and review:
git format-patch master
This command will format all patches that make up the difference between your
working branch and the master branch. They will be saved in the local
directory; to store them elsewhere read up on the '-o' option.
==Fixing your patch==
So you sent off your patch to the ML and you got a few suggestions back. How
does one fix it? Hopefully you did it on a branch and not the master branch,
otherwise you are going to have a much tougher time. :)
If it was the last patch on a branch:
(edit the required files)
git add <edited files>
git commit --amend
If it was deeper in your patch tree, use {{Ic|git rebase -i}}. Use {{Ic|git log}} to find the sha1 of the commit just before the one you wish to edit (or the unique prefix), and then:
git rebase -i <sha1 from above>
(edit the text file that appears so 'edit' appears next to the commit you wish to modify)
(edit the required files)
git add -u
git commit --amend
git rebase --continue
http://wiki.winehq.org/GitWine has good information on the above, that is where most of this came from. After fixing your patch, you will probably want to rebase it as described above, and then use format-patch to submit it again.
==Sending patches==
A nice way to send patches is to use git send-email, but it requires some initial setup, especially for the smtp client.
If you follow the instructions carefully, it should go fine : [[Msmtp]]
Then you just need to tell git to use msmtp:
git config --global sendemail.smtpserver "/usr/bin/msmtp"
For each git repo, you can specify the email address where the patches should be sent:
git config sendemail.to "pacman-dev@archlinux.org"
Then simply send your patches generated by git format-patch:
git send-email 0001-amazing-new-feature
==Further reading==
Commands you will definitely want to be knowledgeable on:
clone (only once!), branch, checkout, status, pull, fetch, diff, add,
commit, rebase, format-patch
==Advanced hints==
qgit in extra is a great GUI viewer for git repositories. In addition, read up
on 'git-instaweb'.
Used to CVS or SVN-like behavior on commits, where all changes in the local tree are committed? Try using 'git commit -a'.
Not running a black and white console? Then you probably want color in a lot of GIT's console output.
git config --global color.branch auto
git config --global color.diff auto
git config --global color.status auto

Latest revision as of 03:28, 13 October 2015

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