1 @c -*- coding: utf-8; mode: texinfo; -*-
4 @node Working with source code
5 @chapter Working with source code
7 @warning{New contributors should read @ref{Quick start}, and in
8 particular @ref{lily-git}, instead of this chapter.}
10 Advanced contributors will find this material quite useful,
11 particularly if they are working on major new features.
14 * Manually installing lily-git.tcl::
16 * Basic Git procedures::
17 * Advanced Git procedures::
19 * Repository directory structure::
20 * Other Git documentation::
24 @node Manually installing lily-git.tcl
25 @section Manually installing lily-git.tcl
27 We have created an easy-to-use GUI to simplify git for new
28 contributors. If you are comfortable with the command-line, then
29 skip ahead to @ref{Starting with Git}.
31 @warning{These instructions are only for people who are @emph{not}
34 @c there's some duplication in this section with stuff covered in
35 @c Quick Start, but moving it into a macro inside included/ would
36 @c be getting a bit icky. -gp
40 If you haven't already, download and install Git.
44 @item Windows users: download the @code{.exe} file labeled
45 @qq{Full installer for official Git} from:
48 @uref{http://code.google.com/p/msysgit/downloads/list}
51 @item Other operating systems: either install @command{git} with
52 your package manager, or download it from the @qq{Binaries}
56 @uref{http://git-scm.com/download}
63 Download the @command{lily-git.tcl} script from:
65 @c don't change the cgit link below to gitweb; gitweb uses
66 @c long filenames like "scripts_auxiliar_lily-git.tcl"
69 @uref{http://git.sv.gnu.org/cgit/lilypond.git/plain/scripts/auxiliar/lily-git.tcl}
73 To run the program from the command line, navigate to the
74 directory containing @command{lily-git.tcl} and enter:
81 Click on the @qq{Get source} button.
83 This will create a directory called @file{lilypond-git/} within
84 your home directory, and will download the source code into that
85 directory (around 150@tie{}Mb). When the process is finished, the
86 @qq{Command output} window will display @qq{Done}, and the button
87 label will change to say @qq{Update source}.
90 Navigate to the @file{lilypond-git/} directory to view the source
95 @warning{Throughout the rest of this manual, most command-line
96 input should be entered from @file{$LILYPOND_GIT}. This is
97 referred to as the @emph{top source directory}.}
99 Further instructions are in @ref{How to use lily-git}.
102 @node Starting with Git
103 @section Starting with Git
105 Using the Git program directly (as opposed to using the
106 @command{lily-git.tcl} GUI) allows you to have much greater control
107 over the contributing process. You should consider using Git if
108 you want to work on complex projects, or if you want to work on
109 multiple projects concurrently.
114 * Git for the impatient::
115 * Other repositories::
116 * Downloading remote branches::
121 @subsection Setting up
123 @warning{These instructions assume that you are using the
124 command-line version of Git 1.7 or higher.}
128 * Initializing a repository::
134 @unnumberedsubsubsec Installing Git
136 If you are using a Unix-based machine, the easiest way to download
137 and install Git is through a package manager such as @command{rpm}
138 or @command{apt-get} -- the installation is generally automatic.
139 The only required package is (usually) called @command{git-core},
140 although some of the auxiliary @command{git@var{*}} packages are
141 also useful (such as @command{gitk}).
143 Alternatively, you can visit the Git website
144 (@uref{http://git-scm.com/}) for downloadable binaries and
148 @node Initializing a repository
149 @unnumberedsubsubsec Initializing a repository
151 Once Git is installed, get a copy of the source code:
154 git clone git://git.sv.gnu.org/lilypond.git ~/lilypond-git
157 The above command will put the it in @file{~/lilypond-git}, where
158 @code{~} represents your home directory.
160 @subsubheading Technical details
162 This creates (within the @file{$LILYPOND_GIT} directory) a
163 subdirectory called @file{.git/}, which Git uses to keep track of
164 changes to the repository, among other things. Normally you don't
165 need to access it, but it's good to know it's there.
168 @node Configuring Git
169 @unnumberedsubsubsec Configuring Git
171 @warning{Throughout the rest of this manual, all command-line
172 input should be entered from the top directory of the Git
173 repository being discussed (eg. @file{$LILYPOND_GIT}). This is
174 referred to as the @emph{top source directory}.}
176 Before working with the copy of the main LilyPond repository, you
177 should configure some basic settings with the
178 @command{git@tie{}config} command. Git allows you to set both
179 global and repository-specific options.
181 To configure settings that affect all repositories, use the
182 @option{--global} command line option. For example, the first
183 two options that you should always set are your @var{name} and
184 @var{email}, since Git needs these to keep track of commit
188 git config --global user.name "@var{John Smith}"
189 git config --global user.email @var{john@@example.com}
192 To configure Git to use colored output where possible, use:
195 git config --global color.ui auto
198 The text editor that opens when using @command{git@tie{}commit}
199 can also be changed. If none of your editor-related environment
200 variables are set ($GIT_EDITOR, $VISUAL, or $EDITOR), the default
201 editor is usually @command{vi} or @command{vim}. If you're not
202 familiar with either of these, you should probably change the
203 default to an editor that you know how to use. For example, to
204 change the default editor to @command{nano}, enter:
207 git config --global core.editor @var{nano}
210 Finally, and in some ways most importantly, let's make sure that
211 we know what branch we're on. If you're not using LilyDev, add
212 this to your @file{~/.bashrc}:
215 export PS1="\u@\h \w\$(__git_ps1)$ "
218 If you are not using LilyDev, you may need to install the
219 additional @code{git-completion} package, but it is definitely
223 @subsubheading Technical details
225 Git stores the information entered with
226 @command{git@tie{}config@tie{}--global} in the file
227 @file{.gitconfig}, located in your home directory. This file can
228 also be modified directly, without using
229 @command{git@tie{}config}. The @file{.gitconfig} file generated
230 by the above commands would look like this:
235 email = john@@example.com
242 Using the @command{git@tie{}config} command @emph{without} the
243 @option{--global} option configures repository-specific settings,
244 which are stored in the file @file{.git/config}. This file is
245 created when a repository is initialized (using
246 @command{git@tie{}init}), and by default contains these lines:
250 repositoryformatversion = 0
253 logallrefupdates = true
256 However, since different repository-specific options are
257 recommended for different development tasks, it is best to avoid
258 setting any now. Specific recommendations will be mentioned later
262 @node Git for the impatient
263 @subsection Git for the impatient
265 @advanced{The intent of this subsection is to get you working on lilypond as
266 soon as possible. If you want to learn about git, go read
267 @ref{Other Git documentation}.
269 Also, these instructions are designed to eliminate the most common
270 problems we have found in using git. If you already know git and
271 have a different way of working, great! Feel free to ignore the
272 advice in this subsection.}
275 Ok, so you've been using @command{lily-git.tcl} for a while, but
276 it's time to take the next step. Since our review process delays
277 patches by 60-120 hours, and you want to be able to work on other
278 stuff while your previous work is getting reviewed, you're going
279 to use @strong{branches}.
281 You can think of a branch as being a separate copy of the source
282 code. But don't worry about it.
284 @subsubheading Start work: make a new branch
286 Let's pretend you want to add a section to the Contributor's Guide
287 about using branches.
289 Start by updating the repository, then making a new branch. Call
290 the branch anything you want as long as the name starts with
291 @code{dev/}. Branch names that don't begin with @code{dev/} are
292 reserved for special things in lilypond.
296 git pull -r origin master
300 @subsubheading Switch to that branch
302 Nothing has happened to the files yet. Let's change into the new
303 branch. You can think of this as @qq{loading a file}, although in
304 this case it's really @qq{loading a directory and subdirectories
311 Your prompt now shows you that you're on the other branch:
314 gperciva@@LilyDev:~/lilypond-git (dev/cg)$
317 To be able to manage multiple lilypond issues at once, you'll need to switch
318 branches. You should have each lilypond issue on a separate branch.
319 Switching branches is easy:
323 git checkout origin/staging
324 git checkout origin/release/unstable
328 Branches that begin with @code{origin/} are part of the remote repository,
329 rather than your local repository, so when you check them out you get a
330 temporary local branch. You should never make changes directly on a
331 branch beginning with @code{origin/}. You get changes into the remote
332 repository by making them in local branches, and then pushing them to
333 @code{origin/staging} as described below.
335 @subsubheading Make your changes
337 Edit files, then commit them.
344 Remember how I said that switching to a branch was like
345 @qq{loading a directory}? Well, you've just @qq{saved a
346 directory}, so that you can @qq{load} it later.
348 @advanced{If you have used @command{cvs} or @command{svn}, you may
349 be very confused: those programs use @qq{commit} to mean
350 @qq{upload my changes to the shared source repository}.
351 Unfortunately, just to be different, @w{@command{git commit}}
352 means @qq{save my changes to the files}.}
354 When you create a new file, you need to add it to git, then commit it:
357 git add input/regression/avoid-crash-on-condition.ly
362 Edit more files. Commit them again. Edit yet more files, commit
363 them again. Go eat dinner. Switch to @code{master} so you can
364 play with the latest changes from other developers. Switch back
365 to your branch and edit some more. Commit those changes.
367 At this stage, don't worry about how many commits you have.
370 @subsubheading Save commits to external files
372 Branches are nerve-wracking until you get used to them. You can
373 save your hard work as individual @file{.patch} files. Be sure to
374 commit your changes first.
378 git format-patch master
381 I personally have between 4 and 20 of those files saved in a
382 special folder at any point in time. Git experts might laugh as
383 that behavior, but I feel a @emph{lot} better knowing that I've
387 @subsubheading Prepare your branch for review
389 After committing, you can update your branch with the latest master:
394 git pull -r origin master
400 Due to the speed of lilypond development, sometimes
401 @code{master} has changed so much that your branch can no
402 longer be applied to it. In that happens, you will have a merge
403 conflict. Stop for a moment to either cry or have a stiff drink,
404 then proceed to @ref{Merge conflicts}.
407 @subsubheading Upload your branch
409 Finally, you're finished your changes. Time to upload for review.
410 Make sure that you're on your branch, then upload:
418 @subsubheading Wait for reviews
420 While you're waiting for a countdown and reviews, go back to
421 master, make a @code{dev/doc-beams} branch, and start adding doc
422 suggestions from issue 12345 from the tracker. Or make a
423 @code{dev/page-breaks} and fix bug in page breaking. Or whatever.
424 Don't worry, your @code{dev/cg} is safe.
427 @subsubheading Combining commits (optional unless you have broken commits)
429 Does the history of your branch look good?
435 If you have a lot of commits on your branch, you might want to
436 combine some of them. Alternately, you may like your commits, but
437 want to edit the commit messages.
443 Follow instructions on the screen.
445 @warning{This step gives you the power to completely lose your
446 work. Make a backup of your commits by saving them to
447 @file{.patch} files before playing with this. If you do lose
448 your work, don't despair. You can get it back by using @code{git reflog}.
449 The use of @code{git reflog} is not covered here.}
451 @warning{If any of the commits on your branch represent partial work that will
452 not pass @var{make && make doc}, you @strong{must} squash these
453 commits into a working commit. Otherwise, your push will break staging
454 and will not be able to be merged to master. In general, you will
455 be safer to have one commit per push.}
458 @subsubheading Push to staging
460 When you've got the coveted @code{Patch-push} status, time to
465 git rebase origin/staging dev/cg~0
469 @warning{Do not skip the @command{gitk} step; a quick 5-second
470 check of the visual history can save a great deal of frustration
471 later on. You should see a set of your commits that are ahead of
472 @code{origin/staging}, with no label for the top commit -- only a
475 @warning{If @code{origin/staging} and @code{origin/master} are the
476 same commit, your branch (@code{dev/cg} in the example) will also
477 be at the top of the @code{gitk} tree. This is normal.}
479 If everything looks good, push it:
482 git push origin HEAD:staging
485 Then change back to your working branch:
491 @warning{It is a best practice to avoid rebasing any of your branches
492 to @code{origin/staging}. If @code{origin/staging} is broken, it
493 will be deleted and rebuilt. If you have rebased one of your branches
494 to @code{origin/staging}, the broken commits can end up in your branch.
495 The commands given above do the rebase on a temporary branch, and avoid
496 changing your working branch.}
499 @subsubheading Delete your branch (safe)
501 After a few hours, if there's nothing wrong with your branch, it
502 should be automatically moved to @code{origin/master}. Update,
503 then try removing your branch:
507 git pull -r origin master
511 The last command will fail if the contents of @code{dev/cg} are
512 not present in @code{origin/master}.
515 @subsubheading Delete your branch (UNSAFE)
517 @c don't give explicit commands here -- this is too dangerous to copy and paste
518 Sometimes everything goes wrong. If you want to remove a branch even though
519 it will cause your work to be lost (that is, if the contents of @code{dev/cg}
520 are @strong{not} present in master), follow the instructions in @qq{Delete
521 your branch (safe)}, but replace the @code{-d} on the final line with
525 @node Other repositories
526 @subsection Other repositories
528 We have a few other code repositories.
532 * Grand Unified Builder (GUB)::
534 * yet more repositories::
538 @unnumberedsubsubsec lilypond-extra
540 There is a separate repository for general administrative scripts,
541 as well as pictures and media files for the website. People
542 interested in working on the website should download this
543 repository, and set their @code{$LILYPOND_WEB_MEDIA_GIT}
544 environment variable to point to that repository.
547 @uref{https://github.com/gperciva/lilypond-extra}
550 To configure an environment variable in bash (the default for most
551 GNU/Linux distributions),
554 export LILYPOND_WEB_MEDIA_GIT=$HOME/dir/of/lilypond-extra/
557 Be aware that @code{lilypond-extra} is the definitive source for some binary
558 files - in particular PDF versions of papers concerning LilyPond. To add
559 further PDFs of this sort, all that is necessary is to add the PDF to
560 @code{lilypond-extra} and then add a reference to it in the documentation. The
561 file will then be copied to the website when @code{make website} is run.
563 However, pictures that are also used in the documentation build are mastered in
564 the main git repository. If any of these is changed, it should be updated in
565 git, and then the updates copied to @code{lilypond-extra}.
567 @node Grand Unified Builder (GUB)
568 @unnumberedsubsubsec Grand Unified Builder (GUB)
570 Another item of interest might be the Grand Unified Builder, our
571 cross-platform building tool. Since it is used by other projects as
572 well, it is not stored in our gub repository. For more info, see
573 @uref{http://lilypond.org/gub}.
575 There are two locations for this repository: the version being used to
576 build lilypond, which is at
579 @uref{http://github.com/gperciva/gub}
582 and the original version by Jan Nieuwenhuizen, kept at
585 @uref{http://github.com/janneke/gub}
590 @unnumberedsubsubsec lilypad
592 Our binary releases on MacOS X and Windows contain a lightweight
593 text editor. This code is here:
596 https://github.com/gperciva/lilypad
600 @node yet more repositories
601 @unnumberedsubsubsec yet more repositories
603 There are a few other repositories floating around, which will
604 hopefully be documented in the near future.
607 @node Downloading remote branches
608 @subsection Downloading remote branches
610 @warning{contains obsolete + misleading info}
613 * Organization of remote branches::
614 * LilyPond repository sources::
618 @node Organization of remote branches
619 @unnumberedsubsubsec Organization of remote branches
622 The main LilyPond repository is organized into @emph{branches} to
623 facilitate development. These are often called @emph{remote}
624 branches to distinguish them from @emph{local} branches you might
625 create yourself (see @ref{Using local branches}).
627 The @code{master} branch contains all the source files used to
628 build LilyPond, which includes the program itself (both stable and
629 development releases), the documentation (and its translations),
630 and the website. Generally, the @code{master} branch is expected
631 to compile successfully.
633 The @code{translation} branch is a side branch that
634 allows translators to work without needing to worry about
635 compilation problems. Periodically, the Translation Meister
636 (after verifying that it doesn't break compilation), will
637 @emph{merge} this branch into @code{staging} to incorporate
638 recent translations. Similarly, the @code{master} branch is
639 usually merged into the @code{translation} branch after
640 significant changes to the English documentation. See
641 @ref{Translating the documentation} for details.
644 Most contributors will never need to touch the other branches. If
645 you wish to do so, you will need more familiarity with Git; please
646 see @ref{Other Git documentation}.
649 @item @code{dev/XYZ}:
650 These branches are for individual developers. They store code
651 which is not yet stable enough to be added to the @code{master}
654 @item @code{stable/XYZ}:
655 The branches are kept for archival reasons.
657 @item @code{archive/XYZ}:
658 The branches are kept for archival reasons.
663 @node LilyPond repository sources
664 @unnumberedsubsubsec LilyPond repository sources
667 The recommended source for downloading a copy of the main
671 git://git.sv.gnu.org/lilypond.git
674 However, if your internet router filters out connections using the
675 GIT protocol, or if you experience difficulty connecting via GIT,
676 you can try these other sources:
679 ssh://git.sv.gnu.org/srv/git/lilypond.git
680 http://git.sv.gnu.org/r/lilypond.git
683 The SSH protocol can only be used if your system is properly set
684 up to use it. Also, the HTTP protocol is slowest, so it should
685 only be used as a last resort.
688 @node Basic Git procedures
689 @section Basic Git procedures
693 * The Git contributor's cycle::
694 * Pulling and rebasing::
695 * Using local branches::
696 * Commits and patches::
700 @node The Git contributor's cycle
701 @subsection The Git contributor's cycle
704 Here is a simplified view of the contribution process on Git:
708 Update your local repository by @emph{pulling} the most recent
709 updates from the remote repository.
712 Edit source files within your local repository's @emph{working
716 @emph{Commit} the changes you've made to a local @emph{branch}.
719 Generate a @emph{patch} to share your changes with the developers.
723 @node Pulling and rebasing
724 @subsection Pulling and rebasing
727 When developers push new patches to the @code{git.sv.gnu.org}
728 repository, your local repository is @strong{not} automatically
729 updated. It is important to keep your repository up-to-date by
730 periodically @emph{pulling} the most recent @emph{commits} from
731 the remote branch. Developers expect patches to be as current as
732 possible, since outdated patches require extra work before they
735 Occasionally you may need to rework some of your own modifications
736 to match changes made to the remote branch (see @ref{Merge
737 conflicts}), and it's considerably easier to rework things
738 incrementally. If you don't update your repository along the way,
739 you may have to spend a lot of time resolving branch conflicts and
740 reconfiguring much of the work you've already done.
742 Fortunately, Git is able to resolve certain types of branch
743 conflicts automatically with a process called @emph{rebasing}.
744 When rebasing, Git tries to modify your old commits so they appear
745 as new commits (based on the latest updates). For a more involved
746 explanation, see the @command{git-rebase} man page.
748 To pull without rebasing (recommended for translators), use the
752 git pull # recommended for translators
755 If you're tracking the remote @code{master} branch, you should add
756 the @option{-r} option (short for @option{--rebase}) to keep commits
757 on your local branch current:
760 git pull -r # use with caution when translating
763 If you don't edit translated documentation and don't want to type
764 @option{-r} every time, configure the master branch to rebase by
765 default with this command:
768 git config branch.master.rebase true
771 If pull fails because of a message like
774 error: Your local changes to 'Documentation/learning/tutorial.itely'
775 would be overwritten by merge. Aborting.
782 Documentation/learning/tutorial.itely: needs update
783 refusing to pull with rebase: your working tree is not up-to-date
787 it means that you have modified some files in you working tree
788 without committing changes (see @ref{Commits and patches}); you
789 can use the @command{git@tie{}stash} command to work around this:
792 git stash # save uncommitted changes
793 git pull -r # pull using rebase (translators omit "-r")
794 git stash pop # reapply previously saved changes
797 Note that @command{git@tie{}stash@tie{}pop} will try to apply a
798 patch, and this may create a conflict. If this happens, see
799 @ref{Merge conflicts}.
801 TODO: I think the next paragraph is confusing. Perhaps prepare
802 the reader for new terms `committish' and `head'? -mp
804 @warning{translators and documentation editors, if you have
805 changed committishes in the head of translated files using commits
806 you have not yet pushed to @code{git.sv.gnu.org}, please do not
807 rebase. If you want to avoid wondering whether you should rebase
808 each time you pull, please always use committishes from master
809 and/or translation branch on @code{git.sv.gnu.org}, which
810 in particular implies that you must push your changes to
811 documentation except committishes updates (possibly after having
812 rebased), then update the committishes and push them.}
814 TODO: when committishes automatic conditional update have been
815 tested and documented, append the following to the warning above:
816 Note that using update-committishes make target generally touches
819 @subsubheading Technical details
821 The @command{git@tie{}config} command mentioned above adds the
822 line @code{rebase = true} to the master branch in your local
823 repository's @file{.git/config} file:
828 merge = refs/heads/master
833 @node Using local branches
834 @subsection Using local branches
838 * Creating and removing branches::
839 * Listing branches and remotes::
840 * Checking out branches::
845 @node Creating and removing branches
846 @unnumberedsubsubsec Creating and removing branches
849 Local branches are useful when you're working on several different
850 projects concurrently. To create a new branch, enter:
853 git branch @var{name}
856 To delete a branch, enter:
859 git branch -d @var{name}
862 Git will ask you for confirmation if it sees that data would be
863 lost by deleting the branch. Use @option{-D} instead of @option{-d}
864 to bypass this. Note that you cannot delete a branch if it is
865 currently checked out.
868 @node Listing branches and remotes
869 @unnumberedsubsubsec Listing branches and remotes
871 You can get the exact path or URL of all remote branches by
878 To list Git branches on your local repositories, run
881 git branch # list local branches only
882 git branch -r # list remote branches
883 git branch -a # list all branches
887 @node Checking out branches
888 @unnumberedsubsubsec Checking out branches
890 To know the currently checked out branch, i.e. the branch whose
891 source files are present in your working tree, read the first line
899 The currently checked out branch is also marked with an asterisk
900 in the output of @command{git branch}.
902 You can check out another branch @code{@var{other_branch}}, i.e.
903 check out @code{@var{other_branch}} to the working tree, by
907 git checkout @var{other_branch}
910 Note that it is possible to check out another branch while having
911 uncommitted changes, but it is not recommended unless you know
912 what you are doing; it is recommended to run @command{git status}
913 to check this kind of issue before checking out another branch.
915 @node Merging branches
916 @unnumberedsubsubsec Merging branches
918 To merge branch @code{@var{foo}} into branch @code{@var{bar}},
919 i.e. to @qq{add} all changes made in branch @code{@var{foo}} to
920 branch @code{@var{bar}}, run
923 git checkout @var{bar}
927 If any conflict happens, see @ref{Merge conflicts}.
929 There are common usage cases for merging: as a translator, you will
930 often want the Translations meister to merge @code{master} into
931 @code{translation}; on the other hand, the Translations meister wants
932 to merge @code{translation} into @code{staging} whenever he has
933 checked that @code{translation} builds successfully.
936 @node Commits and patches
937 @subsection Commits and patches
941 * Understanding commits::
945 * Uploading a patch for review::
949 @node Understanding commits
950 @unnumberedsubsubsec Understanding commits
952 Technically, a @emph{commit} is a single point in the history of a
953 branch, but most developers use the term to mean a @emph{commit
954 object}, which stores information about a particular revision. A
955 single commit can record changes to multiple source files, and
956 typically represents one logical set of related changes (such as a
957 bug-fix). You can list the ten most recent commits in your
958 current branch with this command:
961 git log -10 --oneline
964 If you're using an older version of Git and get an @q{unrecognized
965 argument} error, use this instead:
968 git log -10 --pretty=oneline --abbrev-commit
971 More interactive lists of the commits on the remote @code{master}
972 branch are available at
973 @uref{http://git.sv.gnu.org/gitweb/?p=lilypond.git;a=shortlog} and
974 @uref{http://git.sv.gnu.org/cgit/lilypond.git/log/}.
978 @unnumberedsubsubsec Making commits
981 Once you have modified some source files in your working
982 directory, you can make a commit with the following procedure:
986 Make sure you've configured Git properly (see @ref{Configuring
987 Git}). Check that your changes meet the requirements described in
988 @ref{Code style} and/or @ref{Documentation policy}. For advanced
989 edits, you may also want to verify that the changes don't break
990 the compilation process.
993 Run the following command:
1000 to make sure you're on the right branch, and to see which files
1001 have been modified, added or removed, etc. You may need to tell
1002 Git about any files you've added by running one of these:
1005 git add @var{file} # add untracked @var{file} individually
1006 git add . # add all untracked files in current directory
1010 After @command{git@tie{}add}, run @command{git@tie{}status} again
1011 to make sure you got everything. You may also need to modify
1015 Preview the changes about to be committed (to make sure everything
1023 The @code{HEAD} argument refers to the most recent commit on the
1024 currently checked-out branch.
1027 Generate the commit with:
1034 The @option{-a} is short for @option{--all} which includes modified
1035 and deleted files, but only those newly created files that have
1036 previously been added.
1041 @node Commit messages
1042 @unnumberedsubsubsec Commit messages
1045 When you run the @command{git@tie{}commit@tie{}-a} command, Git
1046 automatically opens the default text editor so you can enter a
1047 @emph{commit message}. If you find yourself in a foreign editing
1048 environment, you're probably in @command{vi} or @command{vim}. If
1049 you want to switch to an editor you're more familiar with, quit by
1050 typing @code{:q!} and pressing @code{<Enter>}. See
1051 @ref{Configuring Git} for instructions on changing the default
1054 In any case, Git will open a text file for your commit message
1055 that looks like this:
1059 # Please enter the commit message for your changes. Lines starting
1060 # with '#' will be ignored, and an empty message aborts the commit.
1062 # Changes to be committed:
1063 # (use "git reset HEAD <file>..." to unstage)
1065 # modified: working.itexi
1069 Your commit message should begin with a one-line summary
1070 describing the change (no more than 50 characters long), and if
1071 necessary a blank line followed by several lines giving the
1074 @c $ git log -1 --pretty=medium 4d6f1e5
1076 Doc: add Baerenreiter and Henle solo cello suites
1078 Added comparison of solo cello suite engravings to new essay with
1079 high-res images, fixed cropping on Finale example.
1082 Commit messages often start with a short prefix describing the
1083 general location of the changes. If a commit affects the
1084 documentation in English (or in several languages simultaneously)
1085 the commit message should be prefixed with @qq{Doc:@tie{}}. If
1086 the commit affects only one of the translations, the commit
1087 message should be prefixed with @qq{Doc-@var{**}:@tie{}}, where
1088 @var{**} is the two-letter language code. Commits that affect the
1089 website should use @qq{Web:@tie{}} for English, and
1090 @qq{Web-@var{**}:@tie{}} for the other languages. Also, changes
1091 to a single file are often prefixed with the name of the file
1092 involved. Visit the links listed in @ref{Understanding commits}
1096 @node Making patches
1097 @unnumberedsubsubsec Making patches
1099 If you want to share your changes with other contributors and
1100 developers, you need to generate @emph{patches} from your commits.
1101 We prefer it if you follow the instructions in
1102 @ref{Uploading a patch for review}. However, we present an
1103 alternate method here.
1105 You should always run @command{git@tie{}pull@tie{}-r} (translators
1106 should leave off the @option{-r}) before doing this to ensure that
1107 your patches are as current as possible.
1109 Once you have made one or more commits in your local repository,
1110 and pulled the most recent commits from the remote branch, you can
1111 generate patches from your local commits with the command:
1114 git format-patch origin
1117 The @code{origin} argument refers to the remote tracking branch at
1118 @code{git.sv.gnu.org}. This command generates a separate patch
1119 for each commit that's in the current branch but not in the remote
1120 branch. Patches are placed in the current working directory and
1121 will have names that look something like this:
1124 0001-Doc-Fix-typos.patch
1125 0002-Web-Remove-dead-links.patch
1129 Send an email (must be less than 64 KB) to
1130 @email{lilypond-devel@@gnu.org} briefly explaining your work, with
1131 the patch files attached. Translators should send patches to
1132 @email{translations@@lilynet.net}. After your patches are
1133 reviewed, the developers may push one or more of them to the main
1134 repository or discuss them with you.
1137 @node Uploading a patch for review
1138 @unnumberedsubsubsec Uploading a patch for review
1140 Any non-trivial change should be uploaded to our @qq{Rietveld}
1141 code review website:
1144 @uref{http://codereview.appspot.com/}
1147 @subsubheading @command{git-cl} install
1149 LilyDev users should skip over these @q{install} instructions.
1154 Install @command{git-cl} by entering:
1157 git clone https://github.com/gperciva/git-cl.git
1160 If that command fails for some reason, try this instead:
1163 git clone git://github.com/gperciva/git-cl.git
1167 Add the @file{git-cl/} directory to your PATH,
1168 or create a symbolic link to the @command{git-cl}
1169 and @command{upload.py} scripts in one of your PATH
1170 directories (such as @file{$HOME/bin}).
1172 In Ubuntu (and LilyDev), you can add directories to PATH
1173 by adding this line to a hidden file @file{.bashrc},
1174 located in your home directory:
1177 PATH=~/type-here-directory-containing-git-cl:"$@{PATH@}"
1182 @subsubheading @command{git-cl} configuration
1184 LilyDev users should perform these @q{configuration} instructions.
1188 You must have a google account; please create one if you do not
1191 Note that a google account does not need to be a gmail account; you can
1192 use any email address for your google account when you sign up.
1195 Move into the top source directory and then configure @command{git
1196 cl} with the following commands:
1203 For the @qq{Rietveld server} question, the default value
1204 (@qq{codereview.appspot.com}) should be accepted by
1205 answering with a newline (CR).
1207 The @qq{CC list} question should be answered with:
1210 lilypond-devel@@gnu.org
1213 The @qq{Tree status URL} value should be left blank. So should
1214 the @qq{ViewVC URL} value, since it is used by @command{git cl
1215 dcommit} which is only for repositories which use @command{git
1216 svn} (LilyPond doesn't).
1220 @subsubheading Uploading patch set
1222 @warning{Unless you are familiar with branches, only work on one
1223 set of changes at once.}
1225 There are two methods, depending on your git setup.
1229 @strong{Master branch}: (easy option, and used in @command{lily-git.tcl})
1231 If you added your patch to @code{master}, then:
1235 git cl upload origin/master
1238 @c Mention staging here?
1239 If you have git push ability, make sure that you @emph{remove}
1240 your patch (with @command{git rebase} or @command{git reset})
1241 before pushing other stuff.
1243 @c don't make this one an @example; we don't want to make it easy
1244 @c for people to use this accidently
1245 Notifications of patches are automatically added to our issue
1246 tracker to reduce the chance of patches getting lost. To suppress
1247 this (not recommended), add the @code{-n / --no-code-issue}
1251 @strong{Separate branch}: (complicated option)
1253 Ensure your changes are committed in a separate branch, which
1254 should differ from the reference branch to be used by just the
1255 changes to be uploaded. If the reference branch is to be
1256 origin/master, ensure this is up-to-date. If necessary, use git
1257 rebase to rebase the branch containing the changes to the head of
1258 origin/master. Finally, check out branch with the changes and
1262 git cl upload <reference SHA1 ID>
1266 where <reference SHA1 ID> is the SHA1 ID of the commit to be used
1267 as a reference source for the patch. Generally, this will be the
1268 SHA1 ID of origin/master, and in that case the command:
1271 git cl upload origin/master
1279 First you will see a terminal editor where you can edit the
1280 message that will accompany your patch. @command{git-cl} will
1281 respect the @env{EDITOR} environment variable if defined,
1282 otherwise it will use @command{vi} as the default editor.
1284 After prompting for your Google email address and password, the
1285 patch set will be posted to Rietveld, and you will be given a URL
1288 @warning{Some installations of git-cl fail when uploading a patch
1289 with certain filename extensions. If this happens, it can
1290 generally be fixed by editing the list of exceptions at top of
1293 @subsubheading Announcing your patch set
1295 You should then announce the patch by logging into the code review
1296 issue webpage and using @qq{Publish + Mail Comments} to add a
1297 (mostly bogus) comment to your issue. The text of your comment
1298 will be sent to our developer mailing list.
1300 @warning{There is no automatic notification of a new patch; you
1301 must add a comment yourself.}
1303 @subsubheading Revisions
1305 As revisions are made in response to comments, successive patch sets
1306 for the same issue can be uploaded by reissuing the git-cl command
1307 with the modified branch checked out.
1309 Sometimes in response to comments on revisions, the best way to
1310 work may require creation of a new branch in git. In order to
1311 associate the new branch with an existing Rietveld issue,
1312 the following command can be used:
1315 git cl issue issue-number
1319 where @code{issue-number} is the number of the existing Rietveld
1322 @subsubheading Resetting git cl
1324 If @command{git cl} becomes confused, you can @qq{reset} it by
1331 @subsubheading Wait for a countdown
1333 Your patch will be available for reviews for the next few hours or
1334 days. Three times a week, patches with no known problems are
1335 gathered into a @qq{patch countdown} and their status changed to
1336 @code{patch-countdown}. The countdown is a 48-hour waiting period
1337 in which any final reviews or complaints should be made.
1339 During the countdown, your patch may be set to
1340 @code{patch-needs_work}, indicating that you should fix something
1341 (or at least discuss why the patch needs no modification). If no
1342 problems are found, the patch will be set to @code{patch-push}.
1344 Once a patch has @code{patch-push}, it should be sent to your
1345 mentor for uploading. If you have git push ability, look at
1346 @ref{Pushing to staging}.
1349 @node Advanced Git procedures
1350 @section Advanced Git procedures
1353 @warning{This section is not necessary for normal contributors;
1354 these commands are presented for information for people interested
1355 in learning more about git.}
1357 It is possible to work with several branches on the same local Git
1358 repository; this is especially useful for translators who may have
1359 to deal with both @code{translation} and a stable branch,
1360 e.g. @code{stable/2.12}.
1362 Some Git commands are introduced first, then a workflow with
1363 several Git branches of LilyPond source code is presented.
1368 * Advanced Git concepts::
1369 * Reverting all local changes::
1371 * Applying remote patches::
1372 * Sending and receiving patches via email::
1373 * Cleaning up multiple patches::
1375 * Pushing to staging::
1379 @node Merge conflicts
1380 @subsection Merge conflicts
1383 Occasionally an update may result in conflicts -- this happens
1384 when you and somebody else have modified the same part of the same
1385 file and git cannot figure out how to merge the two versions
1386 together. When this happens, you must manually merge the two
1389 If you need some documentation to understand and resolve
1390 conflicts, see paragraphs @emph{How conflicts are presented} and
1391 @emph{How to resolve conflicts} in @command{git merge} man page.
1393 If all else fails, you can follow the instructions in
1394 @ref{Reverting all local changes}. Be aware that this eliminates
1395 any changes you have made!
1398 @node Advanced Git concepts
1399 @subsection Advanced Git concepts
1402 A bit of Git vocabulary will be explained below. The following is
1403 only introductory; for a better understanding of Git concepts, you
1404 may wish to read @ref{Other Git documentation}.
1406 The @code{git@tie{}pull@tie{}origin} command above is just a
1407 shortcut for this command:
1410 git pull git://git.sv.gnu.org/lilypond.git/ @var{branch}:origin/@var{branch}
1414 where @code{@var{branch}} is typically @code{master} or
1415 @code{translation}; if you do not know or remember, see
1416 @ref{Downloading remote branches} to remember which commands you
1417 issued or which source code you wanted to get.
1419 A @emph{commit} is a set of changes made to the sources; it also
1420 includes the committish of the parent commit, the name and e-mail
1421 of the @emph{author} (the person who wrote the changes), the name
1422 and e-mail of the @emph{committer} (the person who brings these
1423 changes into the Git repository), and a commit message.
1425 A @emph{committish} is the SHA1 checksum of a commit, a number
1426 made of 40 hexadecimal digits, which acts as the internal unique
1427 identifier for this commit. To refer to a particular revision,
1428 don't use vague references like the (approximative) date, simply
1429 copy and paste the committish.
1431 A @emph{branch} is nothing more than a pointer to a particular
1432 commit, which is called the @emph{head} of the branch; when
1433 referring to a branch, one often actually thinks about its head
1434 and the ancestor commits of the head.
1437 @node Reverting all local changes
1438 @subsection Reverting all local changes
1440 Sometimes git will become hopelessly confused, and you just want
1441 to get back to a known, stable state. This command destroys any
1442 local changes you have made in the currently checked-out branch,
1443 but at least you get back to the current online version:
1446 git reset --hard origin/master
1454 The commands above don't only bring you the latest version of the
1455 sources, but also the full history of revisions (revisions, also
1456 called commits, are changes made to the sources), stored in the
1457 @file{.git} directory. You can browse this history with
1460 git log # only shows the logs (author, committish and commit message)
1461 git log -p # also shows diffs
1462 gitk # shows history graphically
1465 @warning{The @code{gitk} command may require a separate
1466 @code{gitk} package, available in the appropriate distribution's
1470 @node Applying remote patches
1471 @subsection Applying remote patches
1474 TODO: Explain how to determine if a patch was created with
1475 @code{git@tie{}format-patch}.
1477 Well-formed git patches created with @code{git@tie{}format-patch}
1478 should be committed with the following command:
1484 Patches created without @code{git@tie{}format-patch} can be
1485 applied in two steps. The first step is to apply the patch to the
1486 working tree and the index:
1489 git apply --index @var{patch}
1493 The second step is to commit the changes and give credit to the
1494 author of the patch. This can be done with the following command:
1497 git commit --author="@var{John Smith} <@var{john@@example.com}>"
1500 Please note that using the @code{--index} option for patching is quite
1501 important here and @emph{cannot} reliably be replaced by using the
1502 @code{-a} option when committing: that would only commit files from the
1503 working tree that are already registered with git, so every file that
1504 the patch actually @emph{adds}, like a regtest for a fixed bug, would
1505 get lost. For the same reason, you should not use the git-independent
1506 @samp{patch} program for applying patches.
1508 @node Sending and receiving patches via email
1509 @subsection Sending and receiving patches via email
1512 The default @code{x-diff} MIME type associated with patch files
1513 (i.e., files whose name ends in @code{.patch}) means that the
1514 encoding of line endings may be changed from UNIX to DOS format
1515 when they are sent as attachments. Attempting to apply such an
1516 inadvertently altered patch will cause git to fail with a message
1517 about @q{whitespace errors}.
1519 The solution to such problems is surprisingly simple---just change
1520 the default file extension of patches generated by git to end in
1521 @code{.txt}, for example:
1524 git config format.suffix '.patch.txt'
1527 This should cause email programs to apply the correct base64
1528 encoding to attached patches.
1530 If you receive a patch with DOS instead of UNIX line-endings, it
1531 can be converted back using the @code{dos2unix} utility.
1533 Lots of useful information on email complications with patches is
1534 provided on the Wine wiki at
1535 @uref{http://wiki.winehq.org/GitWine}.
1538 @node Cleaning up multiple patches
1539 @subsection Cleaning up multiple patches
1541 If you have been developing on your own branch for a while, you
1542 may have more commmits than is really sensible. To revise your
1543 work and condense commits, use:
1546 git rebase origin/master
1547 git rebase -i origin/master
1550 @warning{Be a bit cautious -- if you completely remove commits
1551 during the interactive session, you will... err... completely
1552 remove those commits.}
1556 @subsection Commit access
1558 Most contributors are not able to commit patches directly to the
1559 main repository---only members of the LilyPond development team
1560 have @emph{commit access}. If you are a contributor and are
1561 interested in joining the development team, contact the Project
1562 Manager through the mailing list
1563 (@email{lilypond-devel@@gnu.org}). Generally, only contributors
1564 who have already provided a number of patches which have been
1565 pushed to the main repository will be considered for membership.
1567 If you have been approved by the Project Manager, use the
1568 following procedure to obtain commit access:
1572 If you don't already have one, set up a Savannah user account at
1573 @uref{https://savannah.gnu.org/account/register.php}. If your web
1574 browser responds with an @qq{untrusted connection} message when
1575 you visit the link, follow the steps for including the CAcert root
1576 certificate in your browser, given at
1577 @uref{http://savannah.gnu.org/tls/tutorial/}.
1579 @warning{Savannah will silently put your username in lower-case --
1580 do not try to use capital letters.}
1584 After registering, if you are not logged in automatically, login
1585 at @uref{https://savannah.gnu.org/account/login.php}---this should
1586 take you to your @qq{my} page
1587 (@uref{https://savannah.gnu.org/my/}).
1591 Click on the @qq{My Groups} link to access the @qq{My Group
1592 Membership} page. From there, find the @qq{Request for Inclusion}
1593 box and search for @qq{LilyPond}. Among the search results, check
1594 the box labeled @qq{GNU LilyPond Music Typesetter} and write a
1595 brief (required) message for the Project Manager (@qq{Hey it's
1596 me!} should be fine).
1598 Note that you will not have commit access until the Project
1599 Manager activates your membership. Once your membership is
1600 activated, LilyPond should appear under the heading @qq{Groups I'm
1601 Contributor of} on your @qq{My Group Membership} page.
1605 Generate an SSH @q{rsa} key pair. Enter the following at the
1612 When prompted for a location to save the key, press <ENTER> to
1613 accept the default location (@file{~/.ssh/id_rsa}).
1615 Next you are asked to enter an optional passphrase. On most
1616 systems, if you use a passphrase, you will likely be prompted for
1617 it every time you use @command{git@tie{}push} or
1618 @command{git@tie{}pull}. You may prefer this since it can protect
1619 you from your own mistakes (like pushing when you mean to pull),
1620 though you may find it tedious to keep re-entering it.
1622 You can change/enable/disable your passphrase at any time with:
1625 ssh-keygen -f ~/.ssh/id_rsa -p
1628 Note that the GNOME desktop has a feature which stores your
1629 passphrase for you for an entire GNOME session. If you use a
1630 passphrase to @qq{protect you from yourself}, you will want to
1631 disable this feature, since you'll only be prompted once. Run the
1632 following command, then logout of GNOME and log back in:
1635 gconftool-2 --set -t bool \
1636 /apps/gnome-keyring/daemon-components/ssh false
1639 After setting up your passphrase, your private key is saved as
1640 @file{~/.ssh/id_rsa} and your public key is saved as
1641 @file{~/.ssh/id_rsa.pub}.
1645 Register your public SSH @q{rsa} key with Savannah. From the
1646 @qq{My Account Configuration} page, click on @qq{Edit SSH Keys},
1647 then paste the contents of your @file{~/.ssh/id_rsa.pub} file into
1648 one of the @qq{Authorized keys} text fields, and click
1651 Savannah should respond with something like:
1654 Success: Key #1 seen Keys registered
1659 Configure Git to use the SSH protocol (instead of the GIT
1660 protocol). From your local Git repository, enter:
1663 git config remote.origin.url \
1664 ssh://@var{user}@@git.sv.gnu.org/srv/git/lilypond.git
1668 replacing @var{user} with your Savannah username.
1672 After your membership has been activated and you've configured Git
1673 to use SSH, test the connection with:
1679 SSH should issue the following warning:
1682 The authenticity of host 'git.sv.gnu.org (140.186.70.72)' can't
1684 RSA key fingerprint is
1685 80:5a:b0:0c:ec:93:66:29:49:7e:04:2b:fd:ba:2c:d5.
1686 Are you sure you want to continue connecting (yes/no)?
1689 Make sure the RSA key fingerprint displayed matches the one above.
1690 If it doesn't, respond @qq{no} and check that you configured Git
1691 properly in the previous step. If it does match, respond
1692 @qq{yes}. SSH should then issue another warning:
1695 Warning: Permanently added 'git.sv.gnu.org,140.186.70.72' (RSA) to
1696 the list of known hosts.
1699 The list of known hosts is stored in the file
1700 @file{~/.ssh/known_hosts}.
1702 At this point, you are prompted for your passphrase if you have
1703 one, then Git will attempt a pull.
1705 If @command{git@tie{}pull@tie{}--verbose} fails, you should see
1706 error messages like these:
1709 Permission denied (publickey).
1710 fatal: The remote end hung up unexpectedly
1713 If you get the above error, you may have made a mistake when
1714 registering your SSH key at Savannah. If the key is properly
1715 registered, you probably just need to wait for the Savannah server
1716 to activate it. It usually takes a few minutes for the key to be
1717 active after registering it, but if it still doesn't work after an
1718 hour, ask for help on the mailing list.
1720 If @command{git@tie{}pull@tie{}--verbose} succeeds, the output
1721 will include a @q{From} line that shows @q{ssh} as the protocol:
1724 From ssh://git.sv.gnu.org/srv/git/lilypond
1727 If the protocol shown is not @q{ssh}, check that you configured
1728 Git properly in the previous step.
1732 Test your commit access with a dry run:
1734 @warning{Do not push directly to master; instead, push to staging.
1735 See @ref{Pushing to staging}.}
1738 git push --dry-run --verbose
1741 Note that recent versions of Git (Git 1.6.3 or later) will issue a
1742 big warning if the above command is used. The simplest solution
1743 is to tell Git to push all matching branches by default:
1746 git config push.default matching
1750 Then @code{git@tie{}push} should work as before. For more
1751 details, consult the @code{git@tie{}push} man page.
1755 Repeat the steps from generating an RSA key through to testing
1756 your commit access, for each machine from which you will be
1757 making commits, or you may simply copy the files from your
1758 local @file{~/.ssh} folder to the same folder on the other
1763 @subsubheading Technical details
1767 On Firefox, to view or remove the CAcert root certificate, go to:
1768 Edit > Preferences > Advanced > Encryption > View Certificates >
1769 Authorities > Certificate Name > Root CA > CA Cert Signing
1773 The @command{git@tie{}config} commands above should modify your
1774 local repository's @file{.git/config} file. These lines:
1778 url = git://git.sv.gnu.org/lilypond.git/
1782 should now be changed to:
1786 url = ssh://@var{user}@@git.sv.gnu.org/srv/git/lilypond.git
1790 where @var{user} is your login name on Savannah.
1794 @command{git@tie{}config@tie{}push.default@tie{}matching} command
1795 should add these lines to @file{.git/config}:
1804 Encryption protocols, including ssh, generally do not permit packet
1805 fragmentation to avoid introducing a point of insecurity. This
1806 means that the maximum packet size must not exceed the smallest
1807 MTU (Maximum Transmission Unit) set in the routers along the path.
1808 This smallest MTU is determined by a procedure during call set-up
1809 which relies on the transmission over the path of ICMP packets.
1810 If any of the routers in the path block ICMP packets this mechanism
1811 fails, resulting in the possibility of packets being transmitted
1812 which exceed the MTU of one of the routers. If this happens the
1813 packet is discarded, causing the ssh session to hang, timeout or
1814 terminate with the error message
1817 ssh: connect to host <host ip addr> port 22: Bad file number
1818 fatal: The remote end hung up unexpectedly
1821 depending on precisely when in the proceedings the first large
1822 packet is transmitted. Most routers on the internet have MTU
1823 set to 1500, but routers installed in homes to connect via
1824 broadband may use a slightly smaller MTU for efficient transmission
1825 over ATM. If this problem is encountered a possible work-around is
1826 to set the MTU in the local router to 1500.
1829 @node Pushing to staging
1830 @subsection Pushing to staging
1832 Do not push directly to the git @code{master} branch. Instead,
1833 push to @code{staging}.
1835 You will not see your patch on @code{origin/master} until some
1836 automatic tests have been run. These tests are run every couple
1837 of hours; please wait at least 12 hours before wondering if your
1838 patch has been lost. Note that you can check the commits on
1839 @code{origin/staging} by looking at the git web interface on
1842 It may happen occasionally that the staging branch breaks automated
1843 testing. In this case the automatic move of staging material to
1844 master gets halted in order to avoid broken material entering master.
1845 This is a safety net. Please do not try breaking out from it by
1846 adding fixes on top of staging: in that case the whole sequence will
1847 end up in master after all, defeating the purpose of the system. The
1848 proper fix usually involves rewriting the staging branch and is best
1849 left to core developers after discussion on the developer list.
1851 @subsubheading If your work is in a patch file
1853 Assuming that your patch is in a file called
1854 @file{0001-my-patch.patch}, and you are currently on git master,
1858 git checkout staging
1860 git am 0001-my-patch.patch
1862 git push origin staging
1866 @warning{Do not skip the @command{gitk} step; a quick 5-second
1867 check of the visual history can save a great deal of frustration
1868 later on. You should only see that @command{staging} is only 1
1869 commit ahead of @code{origin/staging}.}
1871 @subsubheading If your work is in a branch
1873 If you are working on branches and your work in is
1874 @code{my_branch_name}, then do:
1877 git checkout staging
1879 git merge my_branch_name
1881 git push origin staging
1884 @warning{Do not skip the @command{gitk} step; a quick 5-second
1885 check of the visual history can save a great deal of frustration
1886 later on. You should see that @code{staging} is only ahead of
1887 @code{origin/staging} by the commits from your branch.}
1891 @node Git on Windows
1892 @section Git on Windows
1894 @warning{We heavily recommend that development be done with our
1895 virtual machine @ref{LilyDev}.}
1897 @c Some of this may duplicate stuff in other sections
1898 @c But it is probably best for windows users to have it all together
1899 @c If necessary, clear this up later -td
1901 TODO: Decide what to do with this... Pare it down? Move
1902 paragraphs next to analogous Unix instructions? -mp
1904 @subsection Background to nomenclature
1906 Git is a system for tracking the changes made to source files by a
1907 distributed set of editors. It is designed to work without a
1908 master repository, but we have chosen to have a master repository
1909 for LilyPond files. Editors hold a local copy of the master
1910 repository together with any changes they have made locally.
1911 Local changes are held in a local @q{branch}, of which there may
1912 be several, but these instructions assume you are using just one.
1913 The files visible in the local repository always correspond to
1914 those on the currently @q{checked out} local branch.
1916 Files are edited on a local branch, and in that state the changes
1917 are said to be @q{unstaged}. When editing is complete, the
1918 changes are moved to being @q{staged for commit}, and finally the
1919 changes are @q{committed} to the local branch. Once committed,
1920 the changes (called a @q{commit}) are given a unique 40-digit
1921 hexadecimal reference number called the @q{Committish} or @q{SHA1
1922 ID} which identifies the commit to Git. Such committed changes
1923 can be sent to the master repository by @q{pushing} them (if you
1924 have write permission) or by sending them by email to someone who
1925 has, either as a complete file or as a @q{diff} or @q{patch}
1926 (which send just the differences from the master repository).
1928 @subsection Installing git
1931 @uref{http://code.google.com/p/msysgit/downloads/list} (note, not
1932 msysGit, which is for Git developers and not PortableGit, which is
1933 not a full git installation) and install it.
1935 Note that most users will not need to install SSH. That is not
1936 required until you have been granted direct push permissions to
1937 the master git repository.
1939 Start Git by clicking on the desktop icon. This will bring up a
1940 command line bash shell. This may be unfamiliar to Windows users.
1941 If so, follow these instructions carefully. Commands are entered
1942 at a $ prompt and are terminated by keying a newline.
1944 @subsection Initialising Git
1946 Decide where you wish to place your local Git repository, creating
1947 the folders in Windows as necessary. Here we call the folder to
1948 contain the repository @code{[path]/Git}, but if you intend using
1949 Git for other projects a directory name like @code{lilypond-git}
1950 might be better. You will need to have space for around
1953 Start the Git bash shell by clicking on the desk-top icon
1954 installed with Git and type
1960 to position the shell at your new Git repository.
1962 Note: if [path] contains folders with names containing spaces use
1974 to initialize your Git repository.
1976 Then type (all on one line; the shell will wrap automatically)
1979 git remote add -ft master origin git://git.sv.gnu.org/lilypond.git
1982 to download the lilypond master files.
1984 @warning{Be patient! Even on a broadband connection this can take
1985 10 minutes or more. Wait for lots of [new tag] messages and the $
1988 We now need to generate a local copy of the downloaded files in a
1989 new local branch. Your local branch needs to have a name. It is
1990 usual to call it @q{master} and we shall do that here.
1995 git checkout -b master origin/master
1998 This creates a second branch called @q{master}. You will see two
1999 warnings (ignore these), and a message advising you that your
2000 local branch @q{master} has been set up to track the remote
2001 branch. You now have two branches, a local branch called
2002 @q{master}, and a tracking branch called @q{origin/master}, which
2003 is a shortened form of @q{remotes/origin/master}.
2005 Return to Windows Explorer and look in your Git repository. You
2006 should see lots of folders. For example, the LilyPond
2007 documentation can be found in [path]/Git/Documentation/.
2009 The Git bash shell is terminated by typing @code{exit} or by
2010 clicking on the usual Windows close-window widget.
2014 Almost all subsequent work will use the Git Graphical User
2015 Interface, which avoids having to type command line commands. To
2016 start Git GUI first start the Git bash shell by clicking on the
2017 desktop icon, and type
2024 The Git GUI will open in a new window. It contains four panels
2025 and 7 pull-down menus. At this stage do not use any of the
2026 commands under Branch, Commit, Merge or Remote. These will be
2029 The top panel on the left contains the names of files which you
2030 are in the process of editing (Unstaged Changes), and the lower
2031 panel on the left contains the names of files you have finished
2032 editing and have staged ready for committing (Staged Changes). At
2033 present, these panels will be empty as you have not yet made any
2034 changes to any file. After a file has been edited and saved the
2035 top panel on the right will display the differences between the
2036 edited file selected in one of the panels on the left and the last
2037 version committed on the current branch.
2039 The panel at bottom right is used to enter a descriptive message
2040 about the change before committing it.
2042 The Git GUI is terminated by entering CNTL-Q while it is the
2043 active window or by clicking on the usual Windows close-window
2046 @subsection Personalising your local git repository
2048 Open the Git GUI, click on
2054 and enter your name and email address in the left-hand (Git
2055 Repository) panel. Leave everything else unchanged and save it.
2057 Note that Windows users must leave the default setting for line
2058 endings unchanged. All files in a git repository must have lines
2059 terminated by just a LF, as this is required for Merge to work,
2060 but Windows files are terminated by CRLF by default. The git
2061 default setting causes the line endings of files in a Windows git
2062 repository to be flipped automatically between LF and CRLF as
2063 required. This enables files to be edited by any Windows editor
2064 without causing problems in the git repository.
2066 @subsection Checking out a branch
2068 At this stage you have two branches in your local repository,
2069 both identical. To see them click on
2075 You should have one local branch called @q{master} and one
2076 tracking branch called @q{origin/master}. The latter is your
2077 local copy of the @q{remotes/origin/master} branch in the master
2078 LilyPond repository. The local @q{master} branch is where you
2079 will make your local changes.
2081 When a particular branch is selected, i.e., checked out, the files
2082 visible in your repository are changed to reflect the state of the
2083 files on that branch.
2085 @subsection Updating files from @q{remote/origin/master}
2087 Before starting the editing of a file, ensure your local
2088 repository contains the latest version of the files in the remote
2089 repository by first clicking
2092 Remote -> Fetch from -> origin
2098 This will place the latest version of every file, including all
2099 the changes made by others, into the @q{origin/master} branch of
2100 the tracking branches in your git repository. You can see these
2101 files by checking out this branch, but you must @emph{never} edit
2102 any files while this branch is checked out. Check out your local
2103 @q{master} branch again.
2105 You then need to merge these fetched files into your local
2106 @q{master} branch by clicking on
2109 Merge -> Local Merge
2113 and if necessary select the local @q{master} branch.
2115 Note that a merge cannot be completed if you have made any local
2116 changes which have not yet been committed.
2118 This merge will update all the files in the @q{master} branch to
2119 reflect the current state of the @q{origin/master} branch. If any
2120 of the changes conflict with changes you have made yourself
2121 recently you will be notified of the conflict (see below).
2123 @subsection Editing files
2125 First ensure your @q{master} branch is checked out, then simply
2126 edit the files in your local Git repository with your favourite
2127 editor and save them back there. If any file contains non-ASCII
2128 characters ensure you save it in UTF-8 format. Git will detect
2129 any changes whenever you restart Git GUI and the file names will
2130 then be listed in the Unstaged Changes panel. Or you can click
2131 the Rescan button to refresh the panel contents at any time. You
2132 may break off and resume editing any time.
2134 The changes you have made may be displayed in diff form in the top
2135 right-hand panel of Git GUI by clicking on the file name shown in
2136 one of the left panels.
2138 When your editing is complete, move the files from being Unstaged
2139 to Staged by clicking the document symbol to the left of each
2140 name. If you change your mind it can be moved back by clicking on
2141 the ticked box to the left of the name.
2143 Finally the changes you have made may be committed to your
2144 @q{master} branch by entering a brief message in the Commit
2145 Message box and clicking the Commit button.
2147 If you wish to amend your changes after a commit has been made,
2148 the original version and the changes you made in that commit may
2149 be recovered by selecting
2152 Commit -> Amend Last Commit
2156 or by checking the Amend Last Commit radio button at bottom right.
2157 This will return the changes to the Staged state, so further
2158 editing made be carried out within that commit. This must only be
2159 done @emph{before} the changes have been Pushed or sent to your
2160 mentor for Pushing - after that it is too late and corrections
2161 have to be made as a separate commit.
2164 @subsection Sending changes to @q{remotes/origin/master}
2166 If you do not have write access to @q{remotes/origin/master} you
2167 will need to send your changes by email to someone who does.
2169 First you need to create a diff or patch file containing your
2170 changes. To create this, the file must first be committed. Then
2171 terminate the Git GUI. In the git bash shell first cd to your Git
2178 if necessary, then produce the patch with
2181 git format-patch origin
2184 This will create a patch file for all the locally committed files
2185 which differ from @q{origin/master}. The patch file can be found
2186 in [path]/Git and will have a name formed from the commit message.
2188 @subsection Resolving merge conflicts
2190 As soon as you have committed a changed file your local
2191 @code{master} branch has diverged from @code{origin/master}, and
2192 will remain diverged until your changes have been committed in
2193 @code{remotes/origin/master} and Fetched back into your
2194 @code{origin/master} branch. Similarly, if a new commit has been
2195 made to @code{remotes/origin/master} by someone else and Fetched,
2196 your local @code{master} branch is divergent. You can detect a
2197 divergent branch by clicking on
2200 Repository -> Visualise all branch history
2203 This opens up a very useful new window called @q{gitk}. Use this
2204 to browse all the commits made by yourself and others.
2206 If the diagram at top left of the resulting window does not show
2207 your @code{master} tag on the same node as the
2208 @code{remotes/origin/master} tag your branch has diverged from
2209 @code{origin/master}. This is quite normal if files you have
2210 modified yourself have not yet been Pushed to
2211 @code{remotes/origin/master} and Fetched, or if files modified and
2212 committed by others have been Fetched since you last Merged
2213 @code{origin/master} into your local @code{master} branch.
2215 If a file being merged from @code{origin/master} differs from one
2216 you have modified in a way that cannot be resolved automatically
2217 by git, Merge will report a Conflict which you must resolve by
2218 editing the file to create the version you wish to keep.
2220 This could happen if the person updating
2221 @code{remotes/origin/master} for you has added some changes of his
2222 own before committing your changes to
2223 @code{remotes/origin/master}, or if someone else has changed the
2224 same file since you last fetched the file from
2225 @code{remotes/origin/master}.
2227 Open the file in your editor and look for sections which are
2230 [to be completed when I next have a merge conflict to be sure I
2231 give the right instructions -td]
2234 @subsection Other actions
2236 The instructions above describe the simplest way of using git on
2237 Windows. Other git facilities which may usefully supplement these
2241 @item Using multiple local branches (Create, Rename, Delete)
2242 @item Resetting branches
2243 @item Cherry-picking commits
2244 @item Pushing commits to @w{remote/origin/master}
2245 @item Using gitk to review history
2248 Once familiarity with using git on Windows has been gained the
2249 standard git manuals can be used to learn about these.
2252 @node Repository directory structure
2253 @section Repository directory structure
2256 @c TODO: integrate the roadmap better
2257 @verbatiminclude ROADMAP
2260 @node Other Git documentation
2261 @section Other Git documentation
2265 Official git man pages:
2266 @uref{http://www.kernel.org/pub/software/scm/git/docs/}
2269 More in-depth tutorials: @uref{http://git-scm.com/documentation}
2272 Book about git: @uref{http://progit.org/,Pro Git}
2275 Github help: @uref{http://help.github.com/}
2276 (very highly recommended by Graham)