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388 b.conum *{color:inherit!important}
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390 dt,th.tableblock,td.content,div.footnote{text-rendering:optimizeLegibility}
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399 @media print{*{box-shadow:none!important;text-shadow:none!important}
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407 thead{display:table-header-group}
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414 body.book #header{text-align:center}
417 body.book #header .details span:first-child{margin-left:0!important}
418 body.book #header .details br{display:block}
419 body.book #header .details br+span::before{content:none!important}
420 body.book #toc{border:0!important;text-align:left!important;padding:0!important;margin:0!important}
421 body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-break-before:always}
422 .listingblock code[data-lang]::before{display:block}
423 #footer{padding:0 .9375em}
424 .hide-on-print{display:none!important}
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434 </style>
435 <style>
436 pre>code {
437 display: inline;
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439 </style>
440 </head>
446 </div>
447 </div>
453 <p>This is a tutorial demonstrating the end-to-end workflow of creating a change to
454 the Git tree, sending it for review, and making changes based on comments.</p>
455 </div>
460 source code. The Git workflow steps will largely remain unexplained.</p>
461 </div>
462 </div>
466 <p>This tutorial aims to summarize the following documents, but the reader may find
467 useful additional context:</p>
468 </div>
470 <ul>
471 <li>
473 </li>
474 <li>
476 </li>
477 </ul>
478 </div>
479 </div>
484 </div>
486 <h4 id="_gitvger_kernel_org"><a class="anchor" href="#_gitvger_kernel_org"></a><a href="mailto:git@vger.kernel.org">git@vger.kernel.org</a></h4>
488 <p>This is the main Git project mailing list where code reviews, version
489 announcements, design discussions, and more take place. Those interested in
490 contributing are welcome to post questions here. The Git list requires
491 plain-text-only emails and prefers inline and bottom-posting when replying to
492 mail; you will be CC’d in all replies to you. Optionally, you can subscribe to
493 the list by sending an email to <<a href="mailto:git+subscribe@vger.kernel.org">git+subscribe@vger.kernel.org</a>>
494 (see <a href="https://subspace.kernel.org/subscribing.html" class="bare">https://subspace.kernel.org/subscribing.html</a> for details).
496 available to view in a browser.</p>
497 </div>
498 </div>
500 <h4 id="_git_mentoringgooglegroups_com"><a class="anchor" href="#_git_mentoringgooglegroups_com"></a><a href="https://groups.google.com/forum/#!forum/git-mentoring">git-mentoring@googlegroups.com</a></h4>
502 <p>This mailing list is targeted to new contributors and was created as a place to
503 post questions and receive answers outside of the public eye of the main list.
504 Veteran contributors who are especially interested in helping mentor newcomers
505 are present on the list. In order to avoid search indexers, group membership is
506 required to view messages; anyone can join and no approval is required.</p>
507 </div>
508 </div>
510 <h4 id="_git_devel_on_libera_chat"><a class="anchor" href="#_git_devel_on_libera_chat"></a><a href="https://web.libera.chat/#git-devel">#git-devel</a> on Libera Chat</h4>
512 <p>This IRC channel is for conversations between Git contributors. If someone is
513 currently online and knows the answer to your question, you can receive help
514 in real time. Otherwise, you can read the
516 whether someone answered you. IRC does not allow offline private messaging, so
517 if you try to private message someone and then log out of IRC, they cannot
518 respond to you. It’s better to ask your questions in the channel so that you
519 can be answered if you disconnect and so that others can learn from the
520 conversation.</p>
521 </div>
522 </div>
523 </div>
524 </div>
525 </div>
532 <p>Git is mirrored in a number of locations. Clone the repository from one of them;
533 <a href="https://git-scm.com/downloads" class="bare">https://git-scm.com/downloads</a> suggests one of the best places to clone from is
534 the mirror on GitHub.</p>
535 </div>
538 <pre>$ git clone https://github.com/git/git git
539 $ cd git</pre>
540 </div>
541 </div>
542 </div>
546 <p>To build Git from source, you need to have a handful of dependencies installed
547 on your system. For a hint of what’s needed, you can take a look at
549 external programs and libraries. That document mentions a way to "test-drive"
551 this tutorial.</p>
552 </div>
554 <p>Make sure that your environment has everything you need by building your brand
555 new clone of Git from the above step:</p>
556 </div>
560 </div>
561 </div>
563 <table>
564 <tr>
567 </td>
570 use it as you prefer, here and elsewhere.
571 </td>
572 </tr>
573 </table>
574 </div>
575 </div>
577 <h3 id="identify-problem"><a class="anchor" href="#identify-problem"></a>Identify Problem to Solve</h3>
579 <p>In this tutorial, we will add a new command, <code>git psuh</code>, short for “Pony Saying
580 ‘Um, Hello”’ - a feature which has gone unimplemented despite a high frequency
581 of invocation during users' typical daily workflow.</p>
582 </div>
586 </div>
587 </div>
589 <h3 id="setup-workspace"><a class="anchor" href="#setup-workspace"></a>Set Up Your Workspace</h3>
594 etc., you should check that document and base it on the appropriate branch.</p>
595 </div>
599 development like so:</p>
600 </div>
604 </div>
605 </div>
608 with multiple patches up for review simultaneously.</p>
609 </div>
610 </div>
611 </div>
612 </div>
617 <table>
618 <tr>
621 </td>
623 A reference implementation can be found at
624 <a href="https://github.com/nasamuffin/git/tree/psuh" class="bare">https://github.com/nasamuffin/git/tree/psuh</a>.
625 </td>
626 </tr>
627 </table>
628 </div>
630 <h3 id="add-new-command"><a class="anchor" href="#add-new-command"></a>Adding a New Command</h3>
632 <p>Lots of the subcommands are written as builtins, which means they are
635 codebase, the internal API, and the process of working together as a contributor
636 with the reviewers and maintainer to integrate this change into the system.</p>
637 </div>
640 followed by the name of the subcommand, in a source file named after the
643 point for your command in a function matching the style and signature:</p>
644 </div>
648 </div>
649 </div>
651 <p>We’ll also need to add the declaration of psuh; open up <code>builtin.h</code>, find the
652 declaration for <code>cmd_pull</code>, and add a new line for <code>psuh</code> immediately before it,
653 in order to keep the declarations alphabetically sorted:</p>
654 </div>
658 </div>
659 </div>
661 <p>Be sure to <code>#include "builtin.h"</code> in your <code>psuh.c</code>. You’ll also need to
663 </div>
666 decent starting point as we can now add build rules and register the command.</p>
667 </div>
669 <table>
670 <tr>
673 </td>
675 Your throwaway text, as well as much of the text you will be adding over
676 the course of this tutorial, is user-facing. That means it needs to be
678 Throughout the tutorial, we will mark strings for translation as necessary; you
679 should also do so when writing your user-facing commands in the future.
680 </td>
681 </tr>
682 </table>
683 </div>
686 <pre>int cmd_psuh(int argc, const char **argv, const char *prefix)
687 {
688 printf(_("Pony saying hello goes here.\n"));
689 return 0;
690 }</pre>
691 </div>
692 </div>
694 <p>Let’s try to build it. Open <code>Makefile</code>, find where <code>builtin/pull.o</code> is added
696 alphabetical order. Once you’ve done so, move to the top-level directory and
698 some additional warnings:</p>
699 </div>
703 $ make</pre>
704 </div>
705 </div>
707 <table>
708 <tr>
711 </td>
713 When you are developing the Git project, it’s preferred that you use the
714 <code>DEVELOPER</code> flag; if there’s some reason it doesn’t work for you, you can turn
715 it off, but it’s a good idea to mention the problem to the mailing list.
716 </td>
717 </tr>
718 </table>
719 </div>
721 <p>Great, now your new command builds happily on its own. But nobody invokes it.
723 </div>
726 a <code>cmd_struct</code> to the <code>commands[]</code> array. <code>struct cmd_struct</code> takes a string
727 with the command name, a function pointer to the command implementation, and a
729 <code>cmd_push</code> is registered, copy it, and modify it for <code>cmd_psuh</code>, placing the new
731 </div>
734 we hope to print some data about the user’s current workspace context later,
736 </div>
739 and see if it works. There’s a binary you can use to test with in the
741 </div>
745 </div>
746 </div>
749 </div>
751 <p><code>git status</code> reveals modified <code>Makefile</code>, <code>builtin.h</code>, and <code>git.c</code> as well as
752 untracked <code>builtin/psuh.c</code> and <code>git-psuh</code>. First, let’s take care of the binary,
753 which should be ignored. Open <code>.gitignore</code> in your editor, find <code>/git-pull</code>, and
754 add an entry for your new command in alphabetical order:</p>
755 </div>
758 <pre>...
759 /git-prune-packed
760 /git-psuh
761 /git-pull
762 /git-push
763 /git-quiltimport
764 /git-range-diff
765 ...</pre>
766 </div>
767 </div>
769 <p>Checking <code>git status</code> again should show that <code>git-psuh</code> has been removed from
771 can stage and commit:</p>
772 </div>
775 <pre>$ git add Makefile builtin.h builtin/psuh.c git.c .gitignore
776 $ git commit -s</pre>
777 </div>
778 </div>
780 <p>You will be presented with your editor in order to write a commit message. Start
781 the commit with a 50-column or less subject line, including the name of the
782 component you’re working on, followed by a blank line (always required) and then
783 the body of your commit message, which should provide the bulk of the context.
784 Remember to be explicit and provide the "Why" of your change, especially if it
785 couldn’t easily be understood from your diff. When editing your commit message,
786 don’t remove the <code>Signed-off-by</code> trailer which was added by <code>-s</code> above.</p>
787 </div>
790 <pre>psuh: add a built-in by popular demand
792 Internal metrics indicate this is a command many users expect to be
793 present. So here's an implementation to help drive customer
794 satisfaction and engagement: a pony which doubtfully greets the user,
795 or, a Pony Saying "Um, Hello" (PSUH).
797 This commit message is intentionally formatted to 72 columns per line,
798 starts with a single line as "commit message subject" that is written as
799 if to command the codebase to do something (add this, teach a command
800 that). The body of the message is designed to add information about the
801 commit that is not readily deduced from reading the associated diff,
802 such as answering the question "why?".
805 </div>
806 </div>
813 </div>
815 <p>For the remainder of the tutorial, the subject line only will be listed for the
816 sake of brevity. However, fully-fleshed example commit messages are available
817 on the reference implementation linked at the top of this document.</p>
818 </div>
819 </div>
825 </div>
827 <p>Modify your <code>cmd_psuh</code> implementation to dump the args you’re passed, keeping
829 </div>
832 <pre> int i;
834 ...
836 printf(Q_("Your args (there is %d):\n",
837 "Your args (there are %d):\n",
838 argc),
839 argc);
841 printf("%d: %s\n", i, argv[i]);
843 printf(_("Your current working directory:\n<top-level>%s%s\n"),
845 </div>
846 </div>
850 for you, try <code>cd Documentation/ && ../bin-wrappers/git psuh</code>). That’s not so
851 helpful. So what other context can we get?</p>
852 </div>
855 function body:</p>
856 </div>
859 <pre> const char *cfg_name;
861 ...
863 git_config(git_default_config, NULL);
865 printf(_("No name is found in config\n"));
866 else
868 </div>
869 </div>
873 a specific key ("user.name") and give you the value. There are a number of
874 single-key lookup functions like this one; you can see them all (and more info
875 about how to use <code>git_config()</code>) in <code>Documentation/technical/api-config.txt</code>.</p>
876 </div>
879 </div>
883 </div>
884 </div>
888 </div>
891 <pre>$ git add builtin/psuh.c
893 </div>
894 </div>
896 <table>
897 <tr>
900 </td>
902 Again, the above is for sake of brevity in this tutorial. In a real change
904 message.
905 </td>
906 </tr>
907 </table>
908 </div>
910 <p>Still, it’d be nice to know what the user’s working context is like. Let’s see
911 if we can print the name of the user’s current branch. We can mimic the
912 <code>git status</code> implementation; the printer is located in <code>wt-status.c</code> and we can
914 </div>
916 <p><code>wt_status_print()</code> gets invoked by <code>cmd_status()</code> in <code>builtin/commit.c</code>.
917 Looking at that implementation we see the status config being populated like so:</p>
918 </div>
922 </div>
923 </div>
927 </div>
930 </div>
934 </div>
935 </div>
937 <p>Then modify your <code>cmd_psuh</code> implementation to declare your <code>struct wt_status</code>,
938 prepare it, and print its contents:</p>
939 </div>
942 <pre> struct wt_status status;
944 ...
946 wt_status_prepare(the_repository, &status);
947 git_config(git_default_config, &status);
949 ...
952 </div>
953 </div>
956 </div>
959 </div>
962 <pre>$ git add builtin/psuh.c
964 </div>
965 </div>
968 </div>
972 string; <code>pretty.h</code> has an extremely handy <code>pp_commit_easy()</code> call which doesn’t
973 require a full format object to be passed.</p>
974 </div>
977 </div>
982 </div>
983 </div>
986 the declarations and the logic, respectively.</p>
987 </div>
990 <pre> struct commit *c = NULL;
991 struct strbuf commitline = STRBUF_INIT;
993 ...
995 c = lookup_commit_reference_by_name("origin/master");
997 if (c != NULL) {
998 pp_commit_easy(CMIT_FMT_ONELINE, c, &commitline);
999 printf(_("Current commit: %s\n"), commitline.buf);
1000 }</pre>
1001 </div>
1002 </div>
1004 <p>The <code>struct strbuf</code> provides some safety belts to your basic <code>char*</code>, one of
1005 which is a length member to prevent buffer overruns. It needs to be initialized
1006 nicely with <code>STRBUF_INIT</code>. Keep it in mind when you need to pass around <code>char*</code>.</p>
1007 </div>
1010 with the value there and see what kind of things you can come up with.</p>
1011 </div>
1013 <p><code>pp_commit_easy</code> is a convenience wrapper in <code>pretty.h</code> that takes a single
1014 format enum shorthand, rather than an entire format struct. It then
1015 pretty-prints the commit according to that shorthand. These are similar to the
1017 </div>
1022 </div>
1025 <pre>$ git add builtin/psuh.c
1027 </div>
1028 </div>
1029 </div>
1031 <h3 id="add-documentation"><a class="anchor" href="#add-documentation"></a>Adding Documentation</h3>
1034 community. But hang on just a minute - this isn’t very user-friendly. Run the
1035 following:</p>
1036 </div>
1040 </div>
1041 </div>
1044 </div>
1047 subcommands that Git knows about. You can open these up and take a look to get
1048 acquainted with the format, but then go ahead and make a new file
1050 project, help pages are written with AsciiDoc (see CodingGuidelines, "Writing
1051 Documentation" section). Use the following template to fill out your own
1052 manpage:</p>
1053 </div>
1057 ===========
1059 NAME
1060 ----
1061 git-psuh - Delight users' typo with a shy horse
1064 SYNOPSIS
1065 --------
1066 [verse]
1069 DESCRIPTION
1070 -----------
1071 ...
1073 OPTIONS[[OPTIONS]]
1074 ------------------
1075 ...
1077 OUTPUT
1078 ------
1079 ...
1081 GIT
1082 ---
1084 </div>
1085 </div>
1087 <p>The most important pieces of this to note are the file header, underlined by =,
1088 the NAME section, and the SYNOPSIS, which would normally contain the grammar if
1089 your command took arguments. Try to use well-established manpage headers so your
1090 documentation is consistent with other Git and UNIX manpages; this makes life
1091 easier for your user, who can skip to the section they know contains the
1092 information they need.</p>
1093 </div>
1095 <table>
1096 <tr>
1099 </td>
1102 installed.
1103 </td>
1104 </tr>
1105 </table>
1106 </div>
1109 convert your AsciiDoc to troff which is man-readable like so:</p>
1110 </div>
1113 <pre>$ make all doc
1115 </div>
1116 </div>
1119 </div>
1124 </div>
1125 </div>
1127 <p>While this isn’t as satisfying as running through <code>git help</code>, you can at least
1128 check that your help page looks right.</p>
1129 </div>
1131 <p>You can also check that the documentation coverage is good (that is, the project
1132 sees that your command has been implemented as well as documented) by running
1134 </div>
1137 </div>
1138 </div>
1144 printing usage.</p>
1145 </div>
1148 tool for pulling out options you need to be able to handle, and it takes a
1149 usage string.</p>
1150 </div>
1154 </div>
1157 </div>
1160 </div>
1163 <pre>static const char * const psuh_usage[] = {
1164 N_("git psuh [<arg>...]"),
1165 NULL,
1166 };</pre>
1167 </div>
1168 </div>
1173 </div>
1176 <pre> struct option options[] = {
1177 OPT_END()
1178 };</pre>
1179 </div>
1180 </div>
1182 <p>Finally, before you print your args and prefix, add the call to
1184 </div>
1188 </div>
1189 </div>
1192 specified in <code>options</code> from <code>argv</code> and the locations pointed to from <code>options</code>
1194 <code>parse_options()</code>, or you will be confused if you try to parse <code>argv</code> later.</p>
1195 </div>
1197 <p>It’s worth noting the special argument <code>--</code>. As you may be aware, many Unix
1200 you want to pass as a parameter something which would usually be interpreted as
1201 a flag.) <code>parse_options()</code> will terminate parsing when it reaches <code>--</code> and give
1202 you the rest of the options afterwards, untouched.</p>
1203 </div>
1205 <p>Now that you have a usage hint, you can teach Git how to show it in the general
1206 command list shown by <code>git help git</code> or <code>git help -a</code>, which is generated from
1207 <code>command-list.txt</code>. Find the line for <em>git-pull</em> so you can add your <em>git-psuh</em>
1208 line above it in alphabetical order. Now, we can add some attributes about the
1209 command which impacts where it shows up in the aforementioned help commands. The
1211 means; in those help pages, the commands are sorted according to these
1218 align and delineate them:</p>
1219 </div>
1222 <pre>git-prune-packed plumbingmanipulators
1223 git-psuh mainporcelain info
1224 git-pull mainporcelain remote
1225 git-push mainporcelain remote</pre>
1226 </div>
1227 </div>
1230 your command terminated before anything else interesting happens. Great!</p>
1231 </div>
1234 </div>
1235 </div>
1236 </div>
1237 </div>
1243 Moreover, your patch won’t be accepted into the Git tree without tests. Your
1244 tests should:</p>
1245 </div>
1247 <ul>
1248 <li>
1250 </li>
1251 <li>
1253 </li>
1254 <li>
1256 </li>
1257 </ul>
1258 </div>
1261 </div>
1264 </div>
1266 <h3 id="overview-test-structure"><a class="anchor" href="#overview-test-structure"></a>Overview of Testing Structure</h3>
1270 </div>
1271 </div>
1276 as many of the family/subcmd combinations are full, best practice seems to be
1277 to find a command close enough to the one you’ve added and share its naming
1278 space.</p>
1279 </div>
1283 </div>
1286 <pre>#!/bin/sh
1288 test_description='git-psuh test
1290 This test runs git-psuh and makes sure it does not crash.'
1292 . ./test-lib.sh</pre>
1293 </div>
1294 </div>
1297 formatted results. Let’s make sure that <code>git psuh</code> doesn’t exit poorly and does
1298 mention the right animal somewhere:</p>
1299 </div>
1302 <pre>test_expect_success 'runs correctly with no args and good output' '
1304 grep Pony actual
1305 '</pre>
1306 </div>
1307 </div>
1310 bottom of your script:</p>
1311 </div>
1315 </div>
1316 </div>
1319 </div>
1323 </div>
1324 </div>
1326 <p>You can get an idea of whether you created your new test script successfully
1328 uniqueness, executable bit, and so on.</p>
1329 </div>
1330 </div>
1335 </div>
1338 <pre>$ make
1340 </div>
1341 </div>
1343 <p>You can run the full test suite and ensure <code>git-psuh</code> didn’t break anything:</p>
1344 </div>
1347 <pre>$ cd t/
1349 </div>
1350 </div>
1352 <table>
1353 <tr>
1356 </td>
1359 speak TAP. <code>prove</code> can run concurrently. <code>shuffle</code> randomizes the order the
1360 tests are run in, which makes them resilient against unwanted inter-test
1362 </td>
1363 </tr>
1364 </table>
1365 </div>
1368 </div>
1369 </div>
1370 </div>
1371 </div>
1373 <h2 id="ready-to-share"><a class="anchor" href="#ready-to-share"></a>Getting Ready to Share: Anatomy of a Patch Series</h2>
1376 <p>You may have noticed already that the Git project performs its code reviews via
1377 emailed patches, which are then applied by the maintainer when they are ready
1378 and approved by the community. The Git project does not accept contributions from
1379 pull requests, and the patches emailed for review need to be formatted a
1380 specific way.</p>
1381 </div>
1383 <p>Before taking a look at how to convert your commits into emailed patches,
1385 <a href="https://lore.kernel.org/git/pull.1218.git.git.1645209647.gitgitgadget@gmail.com/">example</a> of the summary view for a patch series on the web interface of
1387 </div>
1391 2022-02-18 18:40 ` [PATCH 1/3] reflog: libify delete reflog function and helpers John Cai via GitGitGadget
1400 2022-02-18 18:40 ` [PATCH 2/3] reflog: call reflog_delete from reflog.c John Cai via GitGitGadget
1403 2022-02-18 18:40 ` [PATCH 3/3] stash: call reflog_delete from reflog.c John Cai via GitGitGadget
1410 2022-02-22 18:30 ` [PATCH v2 1/3] stash: add test to ensure reflog --rewrite --updatref behavior John Cai via GitGitGadget
1413 // continued</pre>
1414 </div>
1415 </div>
1418 </div>
1420 <ul>
1421 <li>
1422 <p>Each commit is sent as a separate email, with the commit message title as
1425 </li>
1426 <li>
1429 </li>
1430 <li>
1433 three patches in the second iteration. Each iteration is sent with a new cover
1434 letter (like "[PATCH v2 0/3]" above), itself a reply to the cover letter of the
1435 previous iteration (more on that below).</p>
1436 </li>
1437 </ul>
1438 </div>
1440 <table>
1441 <tr>
1444 </td>
1448 though).
1449 </td>
1450 </tr>
1451 </table>
1452 </div>
1456 <p>In addition to an email per patch, the Git community also expects your patches
1457 to come with a cover letter. This is an important component of change
1458 submission as it explains to the community from a high level what you’re trying
1459 to do, and why, in a way that’s more apparent than just looking at your
1460 patches.</p>
1461 </div>
1463 <p>The title of your cover letter should be something which succinctly covers the
1464 purpose of your entire topic branch. It’s often in the imperative mood, just
1466 </div>
1467 <hr/>
1470 ---</p>
1471 </div>
1473 <p>The body of the cover letter is used to give additional context to reviewers.
1474 Be sure to explain anything your patches don’t make clear on their own, but
1475 remember that since the cover letter is not recorded in the commit history,
1476 anything that might be useful to future readers of the repository’s history
1477 should also be in your commit messages.</p>
1478 </div>
1481 </div>
1484 <pre>Our internal metrics indicate widespread interest in the command
1485 git-psuh - that is, many users are trying to use it, but finding it is
1486 unavailable, using some unknown workaround instead.
1488 The following handful of patches add the psuh command and implement some
1489 handy features on top of it.
1491 This patchset is part of the MyFirstContribution tutorial and should not
1492 be merged.</pre>
1493 </div>
1494 </div>
1496 <p>At this point the tutorial diverges, in order to demonstrate two
1497 different methods of formatting your patchset and getting it reviewed.</p>
1498 </div>
1500 <p>The first method to be covered is GitGitGadget, which is useful for those
1501 already familiar with GitHub’s common pull request workflow. This method
1502 requires a GitHub account.</p>
1503 </div>
1506 more fine-grained control over the emails to be sent. This method requires some
1507 setup which can change depending on your system and will not be covered in this
1508 tutorial.</p>
1509 </div>
1511 <p>Regardless of which method you choose, your engagement with reviewers will be
1512 the same; the review process will be covered after the sections on GitGitGadget
1514 </div>
1515 </div>
1516 </div>
1517 </div>
1519 <h2 id="howto-ggg"><a class="anchor" href="#howto-ggg"></a>Sending Patches via GitGitGadget</h2>
1522 <p>One option for sending patches is to follow a typical pull request workflow and
1523 send your patches out via GitGitGadget. GitGitGadget is a tool created by
1524 Johannes Schindelin to make life as a Git contributor easier for those used to
1525 the GitHub PR workflow. It allows contributors to open pull requests against its
1526 mirror of the Git project, and does some magic to turn the PR into a set of
1527 emails and send them out for you. It also runs the Git continuous integration
1528 suite for you. It’s documented at <a href="https://gitgitgadget.github.io/" class="bare">https://gitgitgadget.github.io/</a>.</p>
1529 </div>
1531 <h3 id="create-fork"><a class="anchor" href="#create-fork"></a>Forking <code>git/git</code> on GitHub</h3>
1533 <p>Before you can send your patch off to be reviewed using GitGitGadget, you will
1534 need to fork the Git project and upload your changes. First thing - make sure
1535 you have a GitHub account.</p>
1536 </div>
1539 button. Place your fork wherever you deem appropriate and create it.</p>
1540 </div>
1541 </div>
1543 <h3 id="upload-to-fork"><a class="anchor" href="#upload-to-fork"></a>Uploading to Your Own Fork</h3>
1548 the URL; then you need to run the following to add, replacing your own URL and
1549 remote name for the examples provided:</p>
1550 </div>
1554 </div>
1555 </div>
1558 </div>
1562 </div>
1563 </div>
1567 get ready to push.</p>
1568 </div>
1572 commits to their own branch.</p>
1573 </div>
1575 <p>As mentioned briefly at the beginning of this document, we are basing our work
1577 workflow.</p>
1578 </div>
1581 <pre>$ git checkout master
1582 $ git pull -r
1583 $ git rebase master psuh</pre>
1584 </div>
1585 </div>
1588 command name choices, be careful when you type the command below.)</p>
1589 </div>
1593 </div>
1594 </div>
1597 </div>
1598 </div>
1600 <h3 id="send-pr-ggg"><a class="anchor" href="#send-pr-ggg"></a>Sending a PR to GitGitGadget</h3>
1602 <p>In order to have your code tested and formatted for review, you need to start by
1604 <a href="https://github.com/gitgitgadget/git" class="bare">https://github.com/gitgitgadget/git</a> and open a PR either with the "New pull
1606 appear with the name of your newly pushed branch.</p>
1607 </div>
1610 respectively as the subject and body of the cover letter for your change. Refer
1612 submission and what content to include in the description.</p>
1613 </div>
1615 <table>
1616 <tr>
1619 </td>
1621 For single-patch contributions, your commit message should already be
1622 meaningful and explain at a high level the purpose (what is happening and why)
1623 of your patch, so you usually do not need any additional context. In that case,
1624 remove the PR description that GitHub automatically generates from your commit
1625 message (your PR description should be empty). If you do need to supply even
1626 more context, you can do so in that space and it will be appended to the email
1627 that GitGitGadget will send, between the three-dash line and the diffstat
1629 submitted).
1630 </td>
1631 </tr>
1632 </table>
1633 </div>
1636 </div>
1637 </div>
1639 <h3 id="run-ci-ggg"><a class="anchor" href="#run-ci-ggg"></a>Running CI and Getting Ready to Send</h3>
1642 this tutorial) then someone will need to give you permission to use the tool.
1643 As mentioned in the GitGitGadget documentation, you just need someone who
1645 will automatically run your PRs through the CI even without the permission given
1647 use the tool.</p>
1648 </div>
1650 <table>
1651 <tr>
1654 </td>
1658 (<a href="https://github.com/gitgitgadget/git/pulls?utf8=%E2%9C%93&q=is%3Apr+is%3Aopen+%22%2Fallow%22">Search:
1663 </td>
1664 </tr>
1665 </table>
1666 </div>
1669 branch again:</p>
1670 </div>
1674 </div>
1675 </div>
1677 <p>In fact, you should continue to make changes this way up until the point when
1679 </div>
1680 </div>
1684 <p>Now that your CI is passing and someone has granted you permission to use
1687 </div>
1688 </div>
1690 <h3 id="responding-ggg"><a class="anchor" href="#responding-ggg"></a>Updating With Comments</h3>
1693 reply to review comments you will receive on the mailing list.</p>
1694 </div>
1696 <p>Once you have your branch again in the shape you want following all review
1697 comments, you can submit again:</p>
1698 </div>
1702 </div>
1703 </div>
1705 <p>Next, go look at your pull request against GitGitGadget; you should see the CI
1706 has been kicked off again. Now while the CI is running is a good time for you
1707 to modify your description at the top of the pull request thread; it will be
1708 used again as the cover letter. You should use this space to describe what
1709 has changed since your previous version, so that your reviewers have some idea
1710 of what they’re looking at. When the CI is done running, you can comment once
1712 changes.</p>
1713 </div>
1714 </div>
1715 </div>
1716 </div>
1718 <h2 id="howto-git-send-email"><a class="anchor" href="#howto-git-send-email"></a>Sending Patches with <code>git send-email</code></h2>
1722 patches. Some benefits of using Git this way include finer grained control of
1723 subject line (for example, being able to use the tag [RFC PATCH] in the subject)
1725 good before going out to the list.</p>
1726 </div>
1728 <h3 id="setup-git-send-email"><a class="anchor" href="#setup-git-send-email"></a>Prerequisite: Setting Up <code>git send-email</code></h3>
1731 provider, and so will not be covered in this tutorial, beyond stating that in
1734 are a number of resources online to help you do so. You will also need to
1735 determine the right way to configure it to use your SMTP server; again, as this
1736 configuration can change significantly based on your system and email setup, it
1737 is out of scope for the context of this tutorial.</p>
1738 </div>
1739 </div>
1741 <h3 id="format-patch"><a class="anchor" href="#format-patch"></a>Preparing Initial Patchset</h3>
1743 <p>Sending emails with Git is a two-part process; before you can prepare the emails
1745 </div>
1749 </div>
1750 </div>
1753 <li>
1755 cover letter template for you. You will need to fill in the
1756 template before you’re ready to send - but for now, the template
1757 will be next to your other patches.</p>
1758 </li>
1759 <li>
1762 can take a directory and send out all the patches from there.</p>
1763 </li>
1764 <li>
1766 commit", on which the recipient is expected to apply the patch
1768 the base commit automatically, which is the merge base of tip
1769 commit of the remote-tracking branch and the specified revision
1770 range.</p>
1771 </li>
1772 <li>
1776 followed the example in the "Set up your workspace" section). If
1778 which means "commits on the current branch since it forked from
1780 </li>
1781 </ol>
1782 </div>
1784 <p>The command will make one patch file per commit. After you
1785 run, you can go have a look at each of the patches with your favorite text
1786 editor and make sure everything looks alright; however, it’s not recommended to
1787 make code fixups via the patch file. It’s a better idea to make the change the
1789 patch.</p>
1790 </div>
1792 <table>
1793 <tr>
1796 </td>
1799 with “[RFC PATCH]” instead of “[PATCH]”. RFC stands for “request for
1801 you’d like to begin the code review process. This can also be used when your
1802 patch is a proposal, but you aren’t sure whether the community wants to solve
1803 the problem with that approach or not - to conduct a sort of design review. You
1805 but want reviewers to look at what they have so far. You can add this flag with
1807 </td>
1808 </tr>
1809 </table>
1810 </div>
1812 <p>Check and make sure that your patches and cover letter template exist in the
1814 </div>
1815 </div>
1817 <h3 id="preparing-cover-letter"><a class="anchor" href="#preparing-cover-letter"></a>Preparing Email</h3>
1819 <p>Since you invoked <code>format-patch</code> with <code>--cover-letter</code>, you’ve already got a
1820 cover letter template ready. Open it up in your favorite editor.</p>
1821 </div>
1824 header is correct. Then modify your <code>Subject:</code> (see <a href="#cover-letter">above</a> for
1825 how to choose good title for your patch series):</p>
1826 </div>
1830 </div>
1831 </div>
1833 <p>Make sure you retain the “[PATCH 0/X]” part; that’s what indicates to the Git
1834 community that this email is the beginning of a patch series, and many
1835 reviewers filter their email for this type of flag.</p>
1836 </div>
1838 <p>You’ll need to add some extra parameters when you invoke <code>git send-email</code> to add
1839 the cover letter.</p>
1840 </div>
1844 </div>
1847 This gives reviewers a summary of what they’re in for when reviewing your topic.
1849 </div>
1853 Makefile | 1 +
1854 builtin.h | 1 +
1855 builtin/psuh.c | 73 ++++++++++++++++++++++++++++++++++++++
1856 git.c | 1 +
1857 t/t9999-psuh-tutorial.sh | 12 +++++++
1859 create mode 100644 Documentation/git-psuh.txt
1860 create mode 100644 builtin/psuh.c
1862 </div>
1863 </div>
1865 <p>Finally, the letter will include the version of Git used to generate the
1866 patches. You can leave that string alone.</p>
1867 </div>
1868 </div>
1870 <h3 id="sending-git-send-email"><a class="anchor" href="#sending-git-send-email"></a>Sending Email</h3>
1873 patches and a cover letter. Time to mail it out! You can send it like this:</p>
1874 </div>
1878 </div>
1879 </div>
1881 <table>
1882 <tr>
1885 </td>
1888 valuable, such as changing the Reply-to address or adding more CC and BCC lines.
1889 </td>
1890 </tr>
1891 </table>
1892 </div>
1894 <table>
1895 <tr>
1898 </td>
1901 list potential reviewers. In addition, you can do <code>git send-email
1902 --cc-cmd='perl contrib/contacts/git-contacts' feature/*.patch</code><sup class="footnote" id="_footnote_contrib-scripts">[<a id="_footnoteref_1" class="footnote" href="#_footnotedef_1" title="View footnote.">1</a>]</sup> to
1904 </td>
1905 </tr>
1906 </table>
1907 </div>
1909 <table>
1910 <tr>
1913 </td>
1915 When you are sending a real patch, it will go to <a href="mailto:git@vger.kernel.org">git@vger.kernel.org</a> - but
1916 please don’t send your patchset from the tutorial to the real mailing list! For
1917 now, you can send it to yourself, to make sure you understand how it will look.
1918 </td>
1919 </tr>
1920 </table>
1921 </div>
1923 <p>After you run the command above, you will be presented with an interactive
1924 prompt for each patch that’s about to go out. This gives you one last chance to
1925 edit or quit sending something (but again, don’t edit code this way). Once you
1926 press <code>y</code> or <code>a</code> at these prompts your emails will be sent! Congratulations!</p>
1927 </div>
1929 <p>Awesome, now the community will drop everything and review your changes. (Just
1930 kidding - be patient!)</p>
1931 </div>
1932 </div>
1936 <p>This section will focus on how to send a v2 of your patchset. To learn what
1938 information on how to handle comments from reviewers.</p>
1939 </div>
1941 <p>We’ll reuse our <code>psuh</code> topic branch for v2. Before we make any changes, we’ll
1942 mark the tip of our v1 branch for easy reference:</p>
1943 </div>
1946 <pre>$ git checkout psuh
1947 $ git branch psuh-v1</pre>
1948 </div>
1949 </div>
1952 reviewer comments. Once the patch series is ready for submission, generate your
1953 patches again, but with some new flags:</p>
1954 </div>
1957 <pre>$ git format-patch -v2 --cover-letter -o psuh/ --range-diff master..psuh-v1 master..</pre>
1958 </div>
1959 </div>
1961 <p>The <code>--range-diff master..psuh-v1</code> parameter tells <code>format-patch</code> to include a
1963 <a href="git-range-diff.html">git-range-diff(1)</a>). This helps tell reviewers about the differences
1964 between your v1 and v2 patches.</p>
1965 </div>
1968 as version "2". For instance, you may notice that your v2 patches are
1972 </div>
1974 <p>After you run this command, <code>format-patch</code> will output the patches to the <code>psuh/</code>
1975 directory, alongside the v1 patches. Using a single directory makes it easy to
1976 refer to the old v1 patches while proofreading the v2 patches, but you will need
1977 to be careful to send out only the v2 patches. We will use a pattern like
1978 <code>psuh/v2-*.patch</code> (not <code>psuh/*.patch</code>, which would match v1 and v2 patches).</p>
1979 </div>
1982 between your last version and now, if it’s something significant. You do not
1983 need the exact same body in your second cover letter; focus on explaining to
1985 </div>
1987 <p>You will also need to go and find the Message-ID of your previous cover letter.
1988 You can either note it when you send the first series, from the output of <code>git
1989 send-email</code>, or you can look it up on the
1992 header. It should match:</p>
1993 </div>
1997 </div>
1998 </div>
2000 <p>Your Message-ID is <code><foo.12345.author@example.com></code>. This example will be used
2001 below as well; make sure to replace it with the correct Message-ID for your
2002 <strong>previous cover letter</strong> - that is, if you’re sending v2, use the Message-ID
2004 </div>
2006 <p>While you’re looking at the email, you should also note who is CC’d, as it’s
2007 common practice in the mailing list to keep all CCs on a thread. You can add
2008 these CC lines directly to your cover letter with a line like so in the header
2009 (before the Subject line):</p>
2010 </div>
2014 </div>
2015 </div>
2017 <p>Now send the emails again, paying close attention to which messages you pass in
2018 to the command:</p>
2019 </div>
2022 <pre>$ git send-email --to=target@example.com
2024 psuh/v2-*.patch</pre>
2025 </div>
2026 </div>
2027 </div>
2029 <h3 id="single-patch"><a class="anchor" href="#single-patch"></a>Bonus Chapter: One-Patch Changes</h3>
2031 <p>In some cases, your very small change may consist of only one patch. When that
2032 happens, you only need to send one email. Your commit message should already be
2033 meaningful and explain at a high level the purpose (what is happening and why)
2034 of your patch, but if you need to supply even more context, you can do so below
2036 format-patch</code> on a single commit, and then edited to add the content between
2038 </div>
2044 Subject: [PATCH] README: change the grammar
2046 I think it looks better this way. This part of the commit message will
2047 end up in the commit-log.
2050 ---
2051 Let's have a wild discussion about grammar on the mailing list. This
2052 part of my email will never end up in the commit log. Here is where I
2053 can add additional context to the mailing list about my intent, outside
2054 of the context of the commit log. This section was added after `git
2055 format-patch` was run, by editing the patch file in a text editor.
2057 README.md | 2 +-
2060 diff --git a/README.md b/README.md
2062 --- a/README.md
2063 +++ b/README.md
2065 Git - fast, scalable, distributed revision control system
2066 =========================================================
2068 -Git is a fast, scalable, distributed revision control system with an
2069 +Git is a fast, scalable, and distributed revision control system with an
2070 unusually rich command set that provides both high-level operations
2071 and full access to internals.
2073 --
2075 </div>
2076 </div>
2077 </div>
2078 </div>
2079 </div>
2084 <p>Please give reviewers enough time to process your initial patch before
2085 sending an updated version. That is, resist the temptation to send a new
2086 version immediately, because others may have already started reviewing
2087 your initial version.</p>
2088 </div>
2090 <p>While waiting for review comments, you may find mistakes in your initial
2091 patch, or perhaps realize a different and better way to achieve the goal
2092 of the patch. In this case you may communicate your findings to other
2093 reviewers as follows:</p>
2094 </div>
2096 <ul>
2097 <li>
2098 <p>If the mistakes you found are minor, send a reply to your patch as if
2099 you were a reviewer and mention that you will fix them in an
2100 updated version.</p>
2101 </li>
2102 <li>
2103 <p>On the other hand, if you think you want to change the course so
2104 drastically that reviews on the initial patch would be a waste of
2105 time (for everyone involved), retract the patch immediately with
2106 a reply like "I am working on a much better approach, so please
2108 </li>
2109 </ul>
2110 </div>
2112 <p>Now, the above is a good practice if you sent your initial patch
2113 prematurely without polish. But a better approach of course is to avoid
2114 sending your patch prematurely in the first place.</p>
2115 </div>
2117 <p>Please be considerate of the time needed by reviewers to examine each
2118 new version of your patch. Rather than seeing the initial version right
2119 now (followed by several "oops, I like this version better than the
2121 single polished version came 2 days later instead, and that version with
2122 fewer mistakes were the only one they would need to review.</p>
2123 </div>
2127 <p>After a few days, you will hopefully receive a reply to your patchset with some
2128 comments. Woohoo! Now you can get back to work.</p>
2129 </div>
2132 made the change suggested, feel the original is better, or that the comment
2133 inspired you to do something a new way which is superior to both the original
2134 and the suggested change. This way reviewers don’t need to inspect your v2 to
2135 figure out whether you implemented their comment or not.</p>
2136 </div>
2138 <p>Reviewers may ask you about what you wrote in the patchset, either in
2139 the proposed commit log message or in the changes themselves. You
2140 should answer these questions in your response messages, but often the
2141 reason why reviewers asked these questions to understand what you meant
2142 to write is because your patchset needed clarification to be understood.</p>
2143 </div>
2145 <p>Do not be satisfied by just answering their questions in your response
2146 and hear them say that they now understand what you wanted to say.
2147 Update your patches to clarify the points reviewers had trouble with,
2148 and prepare your v2; the words you used to explain your v1 to answer
2149 reviewers' questions may be useful thing to use. Your goal is to make
2150 your v2 clear enough so that it becomes unnecessary for you to give the
2151 same explanation to the next person who reads it.</p>
2152 </div>
2154 <p>If you are going to push back on a comment, be polite and explain why you feel
2155 your original is better; be prepared that the reviewer may still disagree with
2156 you, and the rest of the community may weigh in on one side or the other. As
2157 with all code reviews, it’s important to keep an open mind to doing something a
2158 different way than you originally planned; other reviewers have a different
2159 perspective on the project than you do, and may be thinking of a valid side
2160 effect which had not occurred to you. It is always okay to ask for clarification
2161 if you aren’t sure why a change was suggested, or what the reviewer is asking
2162 you to do.</p>
2163 </div>
2165 <p>Make sure your email client has a plaintext email mode and it is turned on; the
2166 Git list rejects HTML email. Please also follow the mailing list etiquette
2167 outlined in the
2169 Note</a>, which are similar to etiquette rules in most open source communities
2170 surrounding bottom-posting and inline replies.</p>
2171 </div>
2175 rebase). Take a look at this
2176 <a href="https://www.oreilly.com/library/view/git-pocket-guide/9781449327507/ch10.html">overview</a>
2177 from O’Reilly. The general idea is to modify each commit which requires changes;
2178 this way, instead of having a patch A with a mistake, a patch B which was fine
2179 and required no upstream reviews in v1, and a patch C which fixes patch A for
2180 v2, you can just ship a v2 with a correct patch A and correct patch B. This is
2182 anyone, that is okay for now! (Later, it may not make sense to do this; take a
2183 look at the section below this one for some context.)</p>
2184 </div>
2185 </div>
2187 <h3 id="after-approval"><a class="anchor" href="#after-approval"></a>After Review Approval</h3>
2189 <p>The Git project has four integration branches: <code>seen</code>, <code>next</code>, <code>master</code>, and
2190 <code>maint</code>. Your change will be placed into <code>seen</code> fairly early on by the maintainer
2191 while it is still in the review process; from there, when it is ready for wider
2192 testing, it will be merged into <code>next</code>. Plenty of early testers use <code>next</code> and
2193 may report issues. Eventually, changes in <code>next</code> will make it to <code>master</code>,
2194 which is typically considered stable. Finally, when a new release is cut,
2197 the use of the various integration branches.</p>
2198 </div>
2200 <p>Back to now: your code has been lauded by the upstream reviewers. It is perfect.
2201 It is ready to be accepted. You don’t need to do anything else; the maintainer
2203 </div>
2206 take some special steps depending on where you are in the process.</p>
2207 </div>
2210 your topic is marked for <code>next</code> - that is, that they plan to merge it to <code>next</code>
2211 but have not yet done so - you should send an email asking the maintainer to
2212 wait a little longer: "I’ve sent v4 of my series and you marked it for <code>next</code>,
2214 </div>
2218 that is, with another commit, based on top of the maintainer’s topic branch as
2219 detailed in <a href="https://github.com/gitster/git" class="bare">https://github.com/gitster/git</a>. Your work is still in the same topic
2220 but is now incremental, rather than a wholesale rewrite of the topic branch.</p>
2221 </div>
2224 if you’re sending your reviews out that way, you should be sure to open your PR
2225 against the appropriate GitGitGadget/Git branch.</p>
2226 </div>
2228 <p>If you’re using <code>git send-email</code>, you can use it the same way as before, but you
2229 should generate your diffs from <code><topic>..<mybranch></code> and base your work on
2231 </div>
2232 </div>
2233 </div>
2234 </div>
2235 </div>
2237 <hr/>
2239 <a href="#_footnoteref_1">1</a>. Scripts under `contrib/` are not part of the core `git` binary and must be called directly. Clone the Git codebase and run `perl contrib/contacts/git-contacts`.
2240 </div>
2241 </div>
2245 </div>
2246 </div>
2247 </body>
2248 </html>