SYNOPSIS

Everyday Git With 20 Commands Or So

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

  • commands are essentialfor anybody who makes a commit, even for somebody who works alone.

  • If you work with other people, you will need commands listed inthe Individual Developer (Participant) section as well.

  • People who play the role need to learn somemore commands in addition to the above.

  • Repository Administration commands are for systemadministrators who are responsible for the care and feedingof Git repositories.

Individual Developer (Standalone)

A standalone individual developer does not exchange patches withother people, and works alone in a single repository, using thefollowing commands.

  • Use a tarball as a starting point for a new repository.

  • add everything under the current directory.

  • make a lightweight, unannotated tag.

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

  • create a new topic branch.

  • revert your botched changes in .

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

  • to see what changes you are committing.

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

  • look at all your changes including the previous commit.

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

  • switch to the master branch.

  • merge a topic branch into your master branch.

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

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

  • git-clone[1] from the upstream to prime your localrepository.

  • and git-fetch[1] from "origin"to keep up-to-date with the upstream.

  • to shared repository, if you adopt CVSstyle shared repository workflow.

  • git-format-patch[1] to prepare e-mail submission, ifyou adopt Linux kernel-style public forum workflow.

  • to send your e-mail submission withoutcorruption by your MUA.

  • git-request-pull[1] to create a summary of changesfor your upstream to pull.

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

  • checkout a new branch mine from master.

  • repeat as needed.

  • extract patches from your branch, relative to master,

  • and email them.

  • return to master, ready to see what’s new

  • git pull fetches from origin by default and merges into thecurrent branch.

  • immediately after pulling, look at the changes done upstreamsince last time we checked, only in thearea we are interested in.

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

  • fetch from a specific branch ALL from a specific repositoryand merge it.

  • revert the pull.

  • garbage collect leftover objects from reverted pull.

  • Push into another repository. 
  1. satellite$ git clone mothership:frotz frotz (1)
  2. satellite$ cd frotz
  3. satellite$ git config --get-regexp '^(remote|branch)\.' (2)
  4. remote.origin.url mothership:frotz
  5. remote.origin.fetch refs/heads/*:refs/remotes/origin/*
  6. branch.master.remote origin
  7. branch.master.merge refs/heads/master
  8. satellite$ git config remote.origin.push \
  9.        +refs/heads/*:refs/remotes/satellite/* (3)
  10. satellite$ edit/compile/test/commit
  11. satellite$ git push origin (4)
  12.  
  13. mothership$ cd frotz
  14. mothership$ git switch master
  15. mothership$ git merge satellite/master (5)

  • mothership machine has a frotz repository under your homedirectory; clone from it to start a repository on the satellitemachine.

  • clone sets these configuration variables by default.It arranges to fetch and store the branches of mothershipmachine to local remotes/origin/* remote-tracking branches.

  • arrange git push to push all local branches totheir corresponding branch of the mothership machine.

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

  • on mothership machine, merge the work done on the satellitemachine into the master branch.

  • Branch off of a specific tag.

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

  • forward port all changes in private2.6.14 branch to master branchwithout a formal "merging". Or longhandgit format-patch -k -m —stdout v2.6.14..private2.6.14 |git am -3 -k

An alternate participant submission mechanism is using thegit request-pull or pull-request mechanisms (e.g as used onGitHub (www.github.com) to notify your upstream of yourcontribution.

Integrator

A fairly central person acting as the integrator in a groupproject receives changes made by others, reviews and integratesthem and publishes the result for others to use, using thesecommands in addition to the ones needed by participants.

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

  • to apply patches e-mailed in from yourcontributors.

  • git-pull[1] to merge from your trusted lieutenants.

  • to prepare and send suggestedalternative to contributors.

  • git-push[1] to publish the bleeding edge.

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

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

  • see which branches haven’t been merged into master yet.Likewise for any other integration branches e.g. maint, and pu (potential updates).

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

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

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

  • rebase internal topic branch that has not been merged to themaster or exposed as a part of a stable branch.

  • restart pu every time from the next.

  • and bundle topic branches still cooking.

  • create a signed tag.

  • make sure master was not accidentally rewound beyond thatalready pushed out.

  • In the output from git show-branch, master should haveeverything ko/master has, and next should haveeverything ko/next has, etc.

  • push out the bleeding edge, together with new tags that pointinto the pushed history.

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

  1. (in .git/config)
  2. [remote "ko"]
  3.     url = kernel.org:/pub/scm/git/git.git
  4.     fetch = refs/heads/*:refs/remotes/ko/*
  5.     push = refs/heads/master
  6.     push = refs/heads/next
  7.     push = +refs/heads/pu
  8.     push = refs/heads/maint

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

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

  • can be used as a _restricted login shell_for shared central repository users.

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

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

has a goodexample of managing a shared central repository.

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

  • gitolite, gerrit code review, cgit and others.
  • We assume the following in /etc/services 
  1. $ grep 9418 /etc/services
  2. git        9418/tcp        # Git Version Control System
  • Run git-daemon to serve /pub/scm from inetd.

The actual configuration line should be on one line.

  • Run git-daemon to serve /pub/scm from xinetd. 
  1. $ cat /etc/xinetd.d/git-daemon
  2. # default: off
  3. # description: The Git server offers access to Git repositories
  4. service git
  5. {
  6.     disable = no
  7.     type            = UNLISTED
  8.     port            = 9418
  9.     socket_type     = stream
  10.     wait            = no
  11.     user            = nobody
  12.     server          = /usr/bin/git-daemon
  13.     server_args     = --inetd --export-all --base-path=/pub/scm
  14.     log_on_failure  += USERID
  15. }

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

  • log-in shell is set to /usr/bin/git-shell, which does notallow anything but git push and . The users requiressh access to the machine.

  • in many distributions /etc/shells needs to list what is usedas the login shell.

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

  • place the developers into the same git group.

  • and make the shared repository writable by the group.

  • 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 cancreate and push version tags.

GIT