Git

NAME

giteveryday - A useful minimum set of commands for Everyday Git

SYNOPSIS

Everyday Git With 20 Commands Or So

DESCRIPTION

Git users can broadly be grouped into four categories for the purposes of describing here a small set of useful commands for everyday Git.

Individual Developer (Standalone)

A standalone individual developer does not exchange patches with other people, and works alone in a single repository, using the following commands.

Examples

Use a tarball as a starting point for a new repository. 
$ tar zxf frotz.tar.gz
$ cd frotz
$ git init
$ git add . (1)
$ git commit -m "import of frotz source tree."
$ git tag v2.43 (2)

  1. add everything under the current directory.

  2. make a lightweight, unannotated tag.

Create a topic branch and develop. 
$ git switch -c alsa-audio (1)
$ edit/compile/test
$ git restore curses/ux_audio_oss.c (2)
$ git add curses/ux_audio_alsa.c (3)
$ edit/compile/test
$ git diff HEAD (4)
$ git commit -a -s (5)
$ edit/compile/test
$ git diff HEAD^ (6)
$ git commit -a --amend (7)
$ git switch master (8)
$ git merge alsa-audio (9)
$ git log --since='3 days ago' (10)
$ git log v2.43.. curses/ (11)

  1. create a new topic branch.

  2. revert your botched changes in curses/ux_audio_oss.c.

  3. you need to tell Git if you added a new file; removal and modification will be caught if you do git commit -a later.

  4. to see what changes you are committing.

  5. commit everything, as you have tested, with your sign-off.

  6. look at all your changes including the previous commit.

  7. amend the previous commit, adding all your new changes, using your original message.

  8. switch to the master branch.

  9. merge a topic branch into your master branch.

  10. review commit logs; other forms to limit output can be combined and include -10 (to show up to 10 commits), --until=2005-12-10, etc.

  11. view only the changes that touch what’s in curses/ directory, since v2.43 tag.

Individual Developer (Participant)

A developer working as a participant in a group project needs to learn how to communicate with others, and uses these commands in addition to the ones needed by a standalone developer.

Examples

Clone the upstream and work on it. Feed changes to upstream. 
$ git clone git://git.kernel.org/pub/scm/.../torvalds/linux-2.6 my2.6
$ cd my2.6
$ git switch -c mine master (1)
$ edit/compile/test; git commit -a -s (2)
$ git format-patch master (3)
$ git send-email --to="person <email@example.com>" 00*.patch (4)
$ git switch master (5)
$ git pull (6)
$ git log -p ORIG_HEAD.. arch/i386 include/asm-i386 (7)
$ git ls-remote --heads http://git.kernel.org/.../jgarzik/libata-dev.git (8)
$ git pull git://git.kernel.org/pub/.../jgarzik/libata-dev.git ALL (9)
$ git reset --hard ORIG_HEAD (10)
$ git gc (11)

  1. checkout a new branch mine from master.

  2. repeat as needed.

  3. extract patches from your branch, relative to master,

  4. and email them.

  5. return to master, ready to see what’s new

  6. git pull fetches from origin by default and merges into the current branch.

  7. immediately after pulling, look at the changes done upstream since last time we checked, only in the area we are interested in.

  8. check the branch names in an external repository (if not known).

  9. fetch from a specific branch ALL from a specific repository and merge it.

  10. revert the pull.

  11. garbage collect leftover objects from reverted pull.

Push into another repository. 
satellite$ git clone mothership:frotz frotz (1)
satellite$ cd frotz
satellite$ git config --get-regexp '^(remote|branch)\.' (2)
remote.origin.url mothership:frotz
remote.origin.fetch refs/heads/*:refs/remotes/origin/*
branch.master.remote origin
branch.master.merge refs/heads/master
satellite$ git config remote.origin.push \
	   +refs/heads/*:refs/remotes/satellite/* (3)
satellite$ edit/compile/test/commit
satellite$ git push origin (4)

mothership$ cd frotz
mothership$ git switch master
mothership$ git merge satellite/master (5)

  1. mothership machine has a frotz repository under your home directory; clone from it to start a repository on the satellite machine.

  2. clone sets these configuration variables by default. It arranges git pull to fetch and store the branches of mothership machine to local remotes/origin/* remote-tracking branches.

  3. arrange git push to push all local branches to their corresponding branch of the mothership machine.

  4. push will stash all our work away on remotes/satellite/* remote-tracking branches on the mothership machine. You could use this as a back-up method. Likewise, you can pretend that mothership "fetched" from you (useful when access is one sided).

  5. on mothership machine, merge the work done on the satellite machine into the master branch.

Branch off of a specific tag. 
$ git switch -c private2.6.14 v2.6.14 (1)
$ edit/compile/test; git commit -a
$ git checkout master
$ git cherry-pick v2.6.14..private2.6.14 (2)

  1. create a private branch based on a well known (but somewhat behind) tag.

  2. forward port all changes in private2.6.14 branch to master branch without a formal "merging". Or longhand
    git format-patch -k -m --stdout v2.6.14..private2.6.14 | git am -3 -k

An alternate participant submission mechanism is using the git request-pull or pull-request mechanisms (e.g. as used on GitHub (www.github.com) to notify your upstream of your contribution.

Integrator

A fairly central person acting as the integrator in a group project receives changes made by others, reviews and integrates them and publishes the result for others to use, using these commands in addition to the ones needed by participants.

This section can also be used by those who respond to git request-pull or pull-request on GitHub (www.github.com) to integrate the work of others into their history. A sub-area lieutenant for a repository will act both as a participant and as an integrator.

Examples

A typical integrator’s Git day. 
$ git status (1)
$ git branch --no-merged master (2)
$ mailx (3)
& s 2 3 4 5 ./+to-apply
& s 7 8 ./+hold-linus
& q
$ git switch -c topic/one master
$ git am -3 -i -s ./+to-apply (4)
$ compile/test
$ git switch -c hold/linus && git am -3 -i -s ./+hold-linus (5)
$ git switch topic/one && git rebase master (6)
$ git switch -C seen next (7)
$ git merge topic/one topic/two && git merge hold/linus (8)
$ git switch maint
$ git cherry-pick master~4 (9)
$ compile/test
$ git tag -s -m "GIT 0.99.9x" v0.99.9x (10)
$ git fetch ko && for branch in master maint next seen (11)
    do
	git show-branch ko/$branch $branch (12)
    done
$ git push --follow-tags ko (13)

  1. see what you were in the middle of doing, if anything.

  2. see which branches haven’t been merged into master yet. Likewise for any other integration branches e.g. maint, next and seen.

  3. read mails, save ones that are applicable, and save others that are not quite ready (other mail readers are available).

  4. apply them, interactively, with your sign-offs.

  5. create topic branch as needed and apply, again with sign-offs.

  6. rebase internal topic branch that has not been merged to the master or exposed as a part of a stable branch.

  7. restart seen every time from the next.

  8. and bundle topic branches still cooking.

  9. backport a critical fix.

  10. create a signed tag.

  11. make sure master was not accidentally rewound beyond that already pushed out.

  12. In the output from git show-branch, master should have everything ko/master has, and next should have everything ko/next has, etc.

  13. push out the bleeding edge, together with new tags that point into the pushed history.

In this example, the ko shorthand points at the Git maintainer’s repository at kernel.org, and looks like this:

(in .git/config)
[remote "ko"]
	url = kernel.org:/pub/scm/git/git.git
	fetch = refs/heads/*:refs/remotes/ko/*
	push = refs/heads/master
	push = refs/heads/next
	push = +refs/heads/seen
	push = refs/heads/maint

Repository Administration

A repository administrator uses the following tools to set up and maintain access to the repository by developers.

  • git-daemon[1] to allow anonymous download from repository.

  • git-shell[1] can be used as a restricted login shell for shared central repository users.

  • git-http-backend[1] provides a server side implementation of Git-over-HTTP ("Smart http") allowing both fetch and push services.

  • gitweb[1] provides a web front-end to Git repositories, which can be set-up using the git-instaweb[1] script.

update hook howto has a good example of managing a shared central repository.

In addition there are a number of other widely deployed hosting, browsing and reviewing solutions such as:

  • gitolite, gerrit code review, cgit and others.

Examples

We assume the following in /etc/services 
$ grep 9418 /etc/services
git		9418/tcp		# Git Version Control System
Run git-daemon to serve /pub/scm from inetd. 
$ grep git /etc/inetd.conf
git	stream	tcp	nowait	nobody \
  /usr/bin/git-daemon git-daemon --inetd --export-all /pub/scm

The actual configuration line should be on one line.

Run git-daemon to serve /pub/scm from xinetd. 
$ cat /etc/xinetd.d/git-daemon
# default: off
# description: The Git server offers access to Git repositories
service git
{
	disable = no
	type            = UNLISTED
	port            = 9418
	socket_type     = stream
	wait            = no
	user            = nobody
	server          = /usr/bin/git-daemon
	server_args     = --inetd --export-all --base-path=/pub/scm
	log_on_failure  += USERID
}

Check your xinetd(8) documentation and setup, this is from a Fedora system. Others might be different.

Give push/pull only access to developers using git-over-ssh.

e.g. those using: $ git push/pull ssh://host.xz/pub/scm/project

$ grep git /etc/passwd (1)
alice:x:1000:1000::/home/alice:/usr/bin/git-shell
bob:x:1001:1001::/home/bob:/usr/bin/git-shell
cindy:x:1002:1002::/home/cindy:/usr/bin/git-shell
david:x:1003:1003::/home/david:/usr/bin/git-shell
$ grep git /etc/shells (2)
/usr/bin/git-shell

  1. log-in shell is set to /usr/bin/git-shell, which does not allow anything but git push and git pull. The users require ssh access to the machine.

  2. in many distributions /etc/shells needs to list what is used as the login shell.

CVS-style shared repository. 
$ grep git /etc/group (1)
git:x:9418:alice,bob,cindy,david
$ cd /home/devo.git
$ ls -l (2)
  lrwxrwxrwx   1 david git    17 Dec  4 22:40 HEAD -> refs/heads/master
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 branches
  -rw-rw-r--   1 david git    84 Dec  4 22:40 config
  -rw-rw-r--   1 david git    58 Dec  4 22:40 description
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 hooks
  -rw-rw-r--   1 david git 37504 Dec  4 22:40 index
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 info
  drwxrwsr-x   4 david git  4096 Dec  4 22:40 objects
  drwxrwsr-x   4 david git  4096 Nov  7 14:58 refs
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 remotes
$ ls -l hooks/update (3)
  -r-xr-xr-x   1 david git  3536 Dec  4 22:40 update
$ cat info/allowed-users (4)
refs/heads/master	alice\|cindy
refs/heads/doc-update	bob
refs/tags/v[0-9]*	david

  1. place the developers into the same git group.

  2. and make the shared repository writable by the group.

  3. use update-hook example by Carl from Documentation/howto/ for branch policy control.

  4. alice and cindy can push into master, only bob can push into doc-update. david is the release manager and is the only person who can create and push version tags.

GIT

Part of the git[1] suite

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