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Member "howto/revert-branch-rebase.html" (15 Dec 2018, 24676 Bytes) of package /linux/misc/git-htmldocs-2.20.1.tar.xz:


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    1 <?xml version="1.0" encoding="UTF-8"?>
    2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
    3     "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
    4 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
    5 <head>
    6 <meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8" />
    7 <meta name="generator" content="AsciiDoc 8.6.10" />
    8 <title>How to revert an existing commit</title>
    9 <style type="text/css">
   10 /* Shared CSS for AsciiDoc xhtml11 and html5 backends */
   11 
   12 /* Default font. */
   13 body {
   14   font-family: Georgia,serif;
   15 }
   16 
   17 /* Title font. */
   18 h1, h2, h3, h4, h5, h6,
   19 div.title, caption.title,
   20 thead, p.table.header,
   21 #toctitle,
   22 #author, #revnumber, #revdate, #revremark,
   23 #footer {
   24   font-family: Arial,Helvetica,sans-serif;
   25 }
   26 
   27 body {
   28   margin: 1em 5% 1em 5%;
   29 }
   30 
   31 a {
   32   color: blue;
   33   text-decoration: underline;
   34 }
   35 a:visited {
   36   color: fuchsia;
   37 }
   38 
   39 em {
   40   font-style: italic;
   41   color: navy;
   42 }
   43 
   44 strong {
   45   font-weight: bold;
   46   color: #083194;
   47 }
   48 
   49 h1, h2, h3, h4, h5, h6 {
   50   color: #527bbd;
   51   margin-top: 1.2em;
   52   margin-bottom: 0.5em;
   53   line-height: 1.3;
   54 }
   55 
   56 h1, h2, h3 {
   57   border-bottom: 2px solid silver;
   58 }
   59 h2 {
   60   padding-top: 0.5em;
   61 }
   62 h3 {
   63   float: left;
   64 }
   65 h3 + * {
   66   clear: left;
   67 }
   68 h5 {
   69   font-size: 1.0em;
   70 }
   71 
   72 div.sectionbody {
   73   margin-left: 0;
   74 }
   75 
   76 hr {
   77   border: 1px solid silver;
   78 }
   79 
   80 p {
   81   margin-top: 0.5em;
   82   margin-bottom: 0.5em;
   83 }
   84 
   85 ul, ol, li > p {
   86   margin-top: 0;
   87 }
   88 ul > li     { color: #aaa; }
   89 ul > li > * { color: black; }
   90 
   91 .monospaced, code, pre {
   92   font-family: "Courier New", Courier, monospace;
   93   font-size: inherit;
   94   color: navy;
   95   padding: 0;
   96   margin: 0;
   97 }
   98 pre {
   99   white-space: pre-wrap;
  100 }
  101 
  102 #author {
  103   color: #527bbd;
  104   font-weight: bold;
  105   font-size: 1.1em;
  106 }
  107 #email {
  108 }
  109 #revnumber, #revdate, #revremark {
  110 }
  111 
  112 #footer {
  113   font-size: small;
  114   border-top: 2px solid silver;
  115   padding-top: 0.5em;
  116   margin-top: 4.0em;
  117 }
  118 #footer-text {
  119   float: left;
  120   padding-bottom: 0.5em;
  121 }
  122 #footer-badges {
  123   float: right;
  124   padding-bottom: 0.5em;
  125 }
  126 
  127 #preamble {
  128   margin-top: 1.5em;
  129   margin-bottom: 1.5em;
  130 }
  131 div.imageblock, div.exampleblock, div.verseblock,
  132 div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
  133 div.admonitionblock {
  134   margin-top: 1.0em;
  135   margin-bottom: 1.5em;
  136 }
  137 div.admonitionblock {
  138   margin-top: 2.0em;
  139   margin-bottom: 2.0em;
  140   margin-right: 10%;
  141   color: #606060;
  142 }
  143 
  144 div.content { /* Block element content. */
  145   padding: 0;
  146 }
  147 
  148 /* Block element titles. */
  149 div.title, caption.title {
  150   color: #527bbd;
  151   font-weight: bold;
  152   text-align: left;
  153   margin-top: 1.0em;
  154   margin-bottom: 0.5em;
  155 }
  156 div.title + * {
  157   margin-top: 0;
  158 }
  159 
  160 td div.title:first-child {
  161   margin-top: 0.0em;
  162 }
  163 div.content div.title:first-child {
  164   margin-top: 0.0em;
  165 }
  166 div.content + div.title {
  167   margin-top: 0.0em;
  168 }
  169 
  170 div.sidebarblock > div.content {
  171   background: #ffffee;
  172   border: 1px solid #dddddd;
  173   border-left: 4px solid #f0f0f0;
  174   padding: 0.5em;
  175 }
  176 
  177 div.listingblock > div.content {
  178   border: 1px solid #dddddd;
  179   border-left: 5px solid #f0f0f0;
  180   background: #f8f8f8;
  181   padding: 0.5em;
  182 }
  183 
  184 div.quoteblock, div.verseblock {
  185   padding-left: 1.0em;
  186   margin-left: 1.0em;
  187   margin-right: 10%;
  188   border-left: 5px solid #f0f0f0;
  189   color: #888;
  190 }
  191 
  192 div.quoteblock > div.attribution {
  193   padding-top: 0.5em;
  194   text-align: right;
  195 }
  196 
  197 div.verseblock > pre.content {
  198   font-family: inherit;
  199   font-size: inherit;
  200 }
  201 div.verseblock > div.attribution {
  202   padding-top: 0.75em;
  203   text-align: left;
  204 }
  205 /* DEPRECATED: Pre version 8.2.7 verse style literal block. */
  206 div.verseblock + div.attribution {
  207   text-align: left;
  208 }
  209 
  210 div.admonitionblock .icon {
  211   vertical-align: top;
  212   font-size: 1.1em;
  213   font-weight: bold;
  214   text-decoration: underline;
  215   color: #527bbd;
  216   padding-right: 0.5em;
  217 }
  218 div.admonitionblock td.content {
  219   padding-left: 0.5em;
  220   border-left: 3px solid #dddddd;
  221 }
  222 
  223 div.exampleblock > div.content {
  224   border-left: 3px solid #dddddd;
  225   padding-left: 0.5em;
  226 }
  227 
  228 div.imageblock div.content { padding-left: 0; }
  229 span.image img { border-style: none; vertical-align: text-bottom; }
  230 a.image:visited { color: white; }
  231 
  232 dl {
  233   margin-top: 0.8em;
  234   margin-bottom: 0.8em;
  235 }
  236 dt {
  237   margin-top: 0.5em;
  238   margin-bottom: 0;
  239   font-style: normal;
  240   color: navy;
  241 }
  242 dd > *:first-child {
  243   margin-top: 0.1em;
  244 }
  245 
  246 ul, ol {
  247     list-style-position: outside;
  248 }
  249 ol.arabic {
  250   list-style-type: decimal;
  251 }
  252 ol.loweralpha {
  253   list-style-type: lower-alpha;
  254 }
  255 ol.upperalpha {
  256   list-style-type: upper-alpha;
  257 }
  258 ol.lowerroman {
  259   list-style-type: lower-roman;
  260 }
  261 ol.upperroman {
  262   list-style-type: upper-roman;
  263 }
  264 
  265 div.compact ul, div.compact ol,
  266 div.compact p, div.compact p,
  267 div.compact div, div.compact div {
  268   margin-top: 0.1em;
  269   margin-bottom: 0.1em;
  270 }
  271 
  272 tfoot {
  273   font-weight: bold;
  274 }
  275 td > div.verse {
  276   white-space: pre;
  277 }
  278 
  279 div.hdlist {
  280   margin-top: 0.8em;
  281   margin-bottom: 0.8em;
  282 }
  283 div.hdlist tr {
  284   padding-bottom: 15px;
  285 }
  286 dt.hdlist1.strong, td.hdlist1.strong {
  287   font-weight: bold;
  288 }
  289 td.hdlist1 {
  290   vertical-align: top;
  291   font-style: normal;
  292   padding-right: 0.8em;
  293   color: navy;
  294 }
  295 td.hdlist2 {
  296   vertical-align: top;
  297 }
  298 div.hdlist.compact tr {
  299   margin: 0;
  300   padding-bottom: 0;
  301 }
  302 
  303 .comment {
  304   background: yellow;
  305 }
  306 
  307 .footnote, .footnoteref {
  308   font-size: 0.8em;
  309 }
  310 
  311 span.footnote, span.footnoteref {
  312   vertical-align: super;
  313 }
  314 
  315 #footnotes {
  316   margin: 20px 0 20px 0;
  317   padding: 7px 0 0 0;
  318 }
  319 
  320 #footnotes div.footnote {
  321   margin: 0 0 5px 0;
  322 }
  323 
  324 #footnotes hr {
  325   border: none;
  326   border-top: 1px solid silver;
  327   height: 1px;
  328   text-align: left;
  329   margin-left: 0;
  330   width: 20%;
  331   min-width: 100px;
  332 }
  333 
  334 div.colist td {
  335   padding-right: 0.5em;
  336   padding-bottom: 0.3em;
  337   vertical-align: top;
  338 }
  339 div.colist td img {
  340   margin-top: 0.3em;
  341 }
  342 
  343 @media print {
  344   #footer-badges { display: none; }
  345 }
  346 
  347 #toc {
  348   margin-bottom: 2.5em;
  349 }
  350 
  351 #toctitle {
  352   color: #527bbd;
  353   font-size: 1.1em;
  354   font-weight: bold;
  355   margin-top: 1.0em;
  356   margin-bottom: 0.1em;
  357 }
  358 
  359 div.toclevel0, div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
  360   margin-top: 0;
  361   margin-bottom: 0;
  362 }
  363 div.toclevel2 {
  364   margin-left: 2em;
  365   font-size: 0.9em;
  366 }
  367 div.toclevel3 {
  368   margin-left: 4em;
  369   font-size: 0.9em;
  370 }
  371 div.toclevel4 {
  372   margin-left: 6em;
  373   font-size: 0.9em;
  374 }
  375 
  376 span.aqua { color: aqua; }
  377 span.black { color: black; }
  378 span.blue { color: blue; }
  379 span.fuchsia { color: fuchsia; }
  380 span.gray { color: gray; }
  381 span.green { color: green; }
  382 span.lime { color: lime; }
  383 span.maroon { color: maroon; }
  384 span.navy { color: navy; }
  385 span.olive { color: olive; }
  386 span.purple { color: purple; }
  387 span.red { color: red; }
  388 span.silver { color: silver; }
  389 span.teal { color: teal; }
  390 span.white { color: white; }
  391 span.yellow { color: yellow; }
  392 
  393 span.aqua-background { background: aqua; }
  394 span.black-background { background: black; }
  395 span.blue-background { background: blue; }
  396 span.fuchsia-background { background: fuchsia; }
  397 span.gray-background { background: gray; }
  398 span.green-background { background: green; }
  399 span.lime-background { background: lime; }
  400 span.maroon-background { background: maroon; }
  401 span.navy-background { background: navy; }
  402 span.olive-background { background: olive; }
  403 span.purple-background { background: purple; }
  404 span.red-background { background: red; }
  405 span.silver-background { background: silver; }
  406 span.teal-background { background: teal; }
  407 span.white-background { background: white; }
  408 span.yellow-background { background: yellow; }
  409 
  410 span.big { font-size: 2em; }
  411 span.small { font-size: 0.6em; }
  412 
  413 span.underline { text-decoration: underline; }
  414 span.overline { text-decoration: overline; }
  415 span.line-through { text-decoration: line-through; }
  416 
  417 div.unbreakable { page-break-inside: avoid; }
  418 
  419 
  420 /*
  421  * xhtml11 specific
  422  *
  423  * */
  424 
  425 div.tableblock {
  426   margin-top: 1.0em;
  427   margin-bottom: 1.5em;
  428 }
  429 div.tableblock > table {
  430   border: 3px solid #527bbd;
  431 }
  432 thead, p.table.header {
  433   font-weight: bold;
  434   color: #527bbd;
  435 }
  436 p.table {
  437   margin-top: 0;
  438 }
  439 /* Because the table frame attribute is overriden by CSS in most browsers. */
  440 div.tableblock > table[frame="void"] {
  441   border-style: none;
  442 }
  443 div.tableblock > table[frame="hsides"] {
  444   border-left-style: none;
  445   border-right-style: none;
  446 }
  447 div.tableblock > table[frame="vsides"] {
  448   border-top-style: none;
  449   border-bottom-style: none;
  450 }
  451 
  452 
  453 /*
  454  * html5 specific
  455  *
  456  * */
  457 
  458 table.tableblock {
  459   margin-top: 1.0em;
  460   margin-bottom: 1.5em;
  461 }
  462 thead, p.tableblock.header {
  463   font-weight: bold;
  464   color: #527bbd;
  465 }
  466 p.tableblock {
  467   margin-top: 0;
  468 }
  469 table.tableblock {
  470   border-width: 3px;
  471   border-spacing: 0px;
  472   border-style: solid;
  473   border-color: #527bbd;
  474   border-collapse: collapse;
  475 }
  476 th.tableblock, td.tableblock {
  477   border-width: 1px;
  478   padding: 4px;
  479   border-style: solid;
  480   border-color: #527bbd;
  481 }
  482 
  483 table.tableblock.frame-topbot {
  484   border-left-style: hidden;
  485   border-right-style: hidden;
  486 }
  487 table.tableblock.frame-sides {
  488   border-top-style: hidden;
  489   border-bottom-style: hidden;
  490 }
  491 table.tableblock.frame-none {
  492   border-style: hidden;
  493 }
  494 
  495 th.tableblock.halign-left, td.tableblock.halign-left {
  496   text-align: left;
  497 }
  498 th.tableblock.halign-center, td.tableblock.halign-center {
  499   text-align: center;
  500 }
  501 th.tableblock.halign-right, td.tableblock.halign-right {
  502   text-align: right;
  503 }
  504 
  505 th.tableblock.valign-top, td.tableblock.valign-top {
  506   vertical-align: top;
  507 }
  508 th.tableblock.valign-middle, td.tableblock.valign-middle {
  509   vertical-align: middle;
  510 }
  511 th.tableblock.valign-bottom, td.tableblock.valign-bottom {
  512   vertical-align: bottom;
  513 }
  514 
  515 
  516 /*
  517  * manpage specific
  518  *
  519  * */
  520 
  521 body.manpage h1 {
  522   padding-top: 0.5em;
  523   padding-bottom: 0.5em;
  524   border-top: 2px solid silver;
  525   border-bottom: 2px solid silver;
  526 }
  527 body.manpage h2 {
  528   border-style: none;
  529 }
  530 body.manpage div.sectionbody {
  531   margin-left: 3em;
  532 }
  533 
  534 @media print {
  535   body.manpage div#toc { display: none; }
  536 }
  537 
  538 
  539 </style>
  540 <script type="text/javascript">
  541 /*<![CDATA[*/
  542 var asciidoc = {  // Namespace.
  543 
  544 /////////////////////////////////////////////////////////////////////
  545 // Table Of Contents generator
  546 /////////////////////////////////////////////////////////////////////
  547 
  548 /* Author: Mihai Bazon, September 2002
  549  * http://students.infoiasi.ro/~mishoo
  550  *
  551  * Table Of Content generator
  552  * Version: 0.4
  553  *
  554  * Feel free to use this script under the terms of the GNU General Public
  555  * License, as long as you do not remove or alter this notice.
  556  */
  557 
  558  /* modified by Troy D. Hanson, September 2006. License: GPL */
  559  /* modified by Stuart Rackham, 2006, 2009. License: GPL */
  560 
  561 // toclevels = 1..4.
  562 toc: function (toclevels) {
  563 
  564   function getText(el) {
  565     var text = "";
  566     for (var i = el.firstChild; i != null; i = i.nextSibling) {
  567       if (i.nodeType == 3 /* Node.TEXT_NODE */) // IE doesn't speak constants.
  568         text += i.data;
  569       else if (i.firstChild != null)
  570         text += getText(i);
  571     }
  572     return text;
  573   }
  574 
  575   function TocEntry(el, text, toclevel) {
  576     this.element = el;
  577     this.text = text;
  578     this.toclevel = toclevel;
  579   }
  580 
  581   function tocEntries(el, toclevels) {
  582     var result = new Array;
  583     var re = new RegExp('[hH]([1-'+(toclevels+1)+'])');
  584     // Function that scans the DOM tree for header elements (the DOM2
  585     // nodeIterator API would be a better technique but not supported by all
  586     // browsers).
  587     var iterate = function (el) {
  588       for (var i = el.firstChild; i != null; i = i.nextSibling) {
  589         if (i.nodeType == 1 /* Node.ELEMENT_NODE */) {
  590           var mo = re.exec(i.tagName);
  591           if (mo && (i.getAttribute("class") || i.getAttribute("className")) != "float") {
  592             result[result.length] = new TocEntry(i, getText(i), mo[1]-1);
  593           }
  594           iterate(i);
  595         }
  596       }
  597     }
  598     iterate(el);
  599     return result;
  600   }
  601 
  602   var toc = document.getElementById("toc");
  603   if (!toc) {
  604     return;
  605   }
  606 
  607   // Delete existing TOC entries in case we're reloading the TOC.
  608   var tocEntriesToRemove = [];
  609   var i;
  610   for (i = 0; i < toc.childNodes.length; i++) {
  611     var entry = toc.childNodes[i];
  612     if (entry.nodeName.toLowerCase() == 'div'
  613      && entry.getAttribute("class")
  614      && entry.getAttribute("class").match(/^toclevel/))
  615       tocEntriesToRemove.push(entry);
  616   }
  617   for (i = 0; i < tocEntriesToRemove.length; i++) {
  618     toc.removeChild(tocEntriesToRemove[i]);
  619   }
  620 
  621   // Rebuild TOC entries.
  622   var entries = tocEntries(document.getElementById("content"), toclevels);
  623   for (var i = 0; i < entries.length; ++i) {
  624     var entry = entries[i];
  625     if (entry.element.id == "")
  626       entry.element.id = "_toc_" + i;
  627     var a = document.createElement("a");
  628     a.href = "#" + entry.element.id;
  629     a.appendChild(document.createTextNode(entry.text));
  630     var div = document.createElement("div");
  631     div.appendChild(a);
  632     div.className = "toclevel" + entry.toclevel;
  633     toc.appendChild(div);
  634   }
  635   if (entries.length == 0)
  636     toc.parentNode.removeChild(toc);
  637 },
  638 
  639 
  640 /////////////////////////////////////////////////////////////////////
  641 // Footnotes generator
  642 /////////////////////////////////////////////////////////////////////
  643 
  644 /* Based on footnote generation code from:
  645  * http://www.brandspankingnew.net/archive/2005/07/format_footnote.html
  646  */
  647 
  648 footnotes: function () {
  649   // Delete existing footnote entries in case we're reloading the footnodes.
  650   var i;
  651   var noteholder = document.getElementById("footnotes");
  652   if (!noteholder) {
  653     return;
  654   }
  655   var entriesToRemove = [];
  656   for (i = 0; i < noteholder.childNodes.length; i++) {
  657     var entry = noteholder.childNodes[i];
  658     if (entry.nodeName.toLowerCase() == 'div' && entry.getAttribute("class") == "footnote")
  659       entriesToRemove.push(entry);
  660   }
  661   for (i = 0; i < entriesToRemove.length; i++) {
  662     noteholder.removeChild(entriesToRemove[i]);
  663   }
  664 
  665   // Rebuild footnote entries.
  666   var cont = document.getElementById("content");
  667   var spans = cont.getElementsByTagName("span");
  668   var refs = {};
  669   var n = 0;
  670   for (i=0; i<spans.length; i++) {
  671     if (spans[i].className == "footnote") {
  672       n++;
  673       var note = spans[i].getAttribute("data-note");
  674       if (!note) {
  675         // Use [\s\S] in place of . so multi-line matches work.
  676         // Because JavaScript has no s (dotall) regex flag.
  677         note = spans[i].innerHTML.match(/\s*\[([\s\S]*)]\s*/)[1];
  678         spans[i].innerHTML =
  679           "[<a id='_footnoteref_" + n + "' href='#_footnote_" + n +
  680           "' title='View footnote' class='footnote'>" + n + "</a>]";
  681         spans[i].setAttribute("data-note", note);
  682       }
  683       noteholder.innerHTML +=
  684         "<div class='footnote' id='_footnote_" + n + "'>" +
  685         "<a href='#_footnoteref_" + n + "' title='Return to text'>" +
  686         n + "</a>. " + note + "</div>";
  687       var id =spans[i].getAttribute("id");
  688       if (id != null) refs["#"+id] = n;
  689     }
  690   }
  691   if (n == 0)
  692     noteholder.parentNode.removeChild(noteholder);
  693   else {
  694     // Process footnoterefs.
  695     for (i=0; i<spans.length; i++) {
  696       if (spans[i].className == "footnoteref") {
  697         var href = spans[i].getElementsByTagName("a")[0].getAttribute("href");
  698         href = href.match(/#.*/)[0];  // Because IE return full URL.
  699         n = refs[href];
  700         spans[i].innerHTML =
  701           "[<a href='#_footnote_" + n +
  702           "' title='View footnote' class='footnote'>" + n + "</a>]";
  703       }
  704     }
  705   }
  706 },
  707 
  708 install: function(toclevels) {
  709   var timerId;
  710 
  711   function reinstall() {
  712     asciidoc.footnotes();
  713     if (toclevels) {
  714       asciidoc.toc(toclevels);
  715     }
  716   }
  717 
  718   function reinstallAndRemoveTimer() {
  719     clearInterval(timerId);
  720     reinstall();
  721   }
  722 
  723   timerId = setInterval(reinstall, 500);
  724   if (document.addEventListener)
  725     document.addEventListener("DOMContentLoaded", reinstallAndRemoveTimer, false);
  726   else
  727     window.onload = reinstallAndRemoveTimer;
  728 }
  729 
  730 }
  731 asciidoc.install();
  732 /*]]>*/
  733 </script>
  734 </head>
  735 <body class="article">
  736 <div id="header">
  737 <h1>How to revert an existing commit</h1>
  738 </div>
  739 <div id="content">
  740 <div id="preamble">
  741 <div class="sectionbody">
  742 <div class="paragraph"><p>One of the changes I pulled into the <em>master</em> branch turns out to
  743 break building Git with GCC 2.95.  While they were well-intentioned
  744 portability fixes, keeping things working with gcc-2.95 was also
  745 important.  Here is what I did to revert the change in the <em>master</em>
  746 branch and to adjust the <em>pu</em> branch, using core Git tools and
  747 barebone Porcelain.</p></div>
  748 <div class="paragraph"><p>First, prepare a throw-away branch in case I screw things up.</p></div>
  749 <div class="listingblock">
  750 <div class="content">
  751 <pre><code>$ git checkout -b revert-c99 master</code></pre>
  752 </div></div>
  753 <div class="paragraph"><p>Now I am on the <em>revert-c99</em> branch.  Let&#8217;s figure out which commit to
  754 revert.  I happen to know that the top of the <em>master</em> branch is a
  755 merge, and its second parent (i.e. foreign commit I merged from) has
  756 the change I would want to undo.  Further I happen to know that that
  757 merge introduced 5 commits or so:</p></div>
  758 <div class="listingblock">
  759 <div class="content">
  760 <pre><code>$ git show-branch --more=4 master master^2 | head
  761 * [master] Merge refs/heads/portable from http://www.cs.berkeley....
  762  ! [master^2] Replace C99 array initializers with code.
  763 --
  764 -  [master] Merge refs/heads/portable from http://www.cs.berkeley....
  765 *+ [master^2] Replace C99 array initializers with code.
  766 *+ [master^2~1] Replace unsetenv() and setenv() with older putenv().
  767 *+ [master^2~2] Include sys/time.h in daemon.c.
  768 *+ [master^2~3] Fix ?: statements.
  769 *+ [master^2~4] Replace zero-length array decls with [].
  770 *  [master~1] tutorial note about git branch</code></pre>
  771 </div></div>
  772 <div class="paragraph"><p>The <em>--more=4</em> above means "after we reach the merge base of refs,
  773 show until we display four more common commits".  That last commit
  774 would have been where the "portable" branch was forked from the main
  775 git.git repository, so this would show everything on both branches
  776 since then.  I just limited the output to the first handful using
  777 <em>head</em>.</p></div>
  778 <div class="paragraph"><p>Now I know <em>master^2~4</em> (pronounce it as "find the second parent of
  779 the <em>master</em>, and then go four generations back following the first
  780 parent") is the one I would want to revert.  Since I also want to say
  781 why I am reverting it, the <em>-n</em> flag is given to <em>git revert</em>.  This
  782 prevents it from actually making a commit, and instead <em>git revert</em>
  783 leaves the commit log message it wanted to use in <em>.msg</em> file:</p></div>
  784 <div class="listingblock">
  785 <div class="content">
  786 <pre><code>$ git revert -n master^2~4
  787 $ cat .msg
  788 Revert "Replace zero-length array decls with []."
  789 
  790 This reverts 6c5f9baa3bc0d63e141e0afc23110205379905a4 commit.
  791 $ git diff HEAD ;# to make sure what we are reverting makes sense.
  792 $ make CC=gcc-2.95 clean test ;# make sure it fixed the breakage.
  793 $ make clean test ;# make sure it did not cause other breakage.</code></pre>
  794 </div></div>
  795 <div class="paragraph"><p>The reverted change makes sense (from reading the <em>diff</em> output), does
  796 fix the problem (from <em>make CC=gcc-2.95</em> test), and does not cause new
  797 breakage (from the last <em>make test</em>).  I&#8217;m ready to commit:</p></div>
  798 <div class="listingblock">
  799 <div class="content">
  800 <pre><code>$ git commit -a -s ;# read .msg into the log,
  801                     # and explain why I am reverting.</code></pre>
  802 </div></div>
  803 <div class="paragraph"><p>I could have screwed up in any of the above steps, but in the worst
  804 case I could just have done <em>git checkout master</em> to start over.
  805 Fortunately I did not have to; what I have in the current branch
  806 <em>revert-c99</em> is what I want.  So merge that back into <em>master</em>:</p></div>
  807 <div class="listingblock">
  808 <div class="content">
  809 <pre><code>$ git checkout master
  810 $ git merge revert-c99 ;# this should be a fast-forward
  811 Updating from 10d781b9caa4f71495c7b34963bef137216f86a8 to e3a693c...
  812  cache.h        |    8 ++++----
  813  commit.c       |    2 +-
  814  ls-files.c     |    2 +-
  815  receive-pack.c |    2 +-
  816  server-info.c  |    2 +-
  817  5 files changed, 8 insertions(+), 8 deletions(-)</code></pre>
  818 </div></div>
  819 <div class="paragraph"><p>There is no need to redo the test at this point.  We fast-forwarded
  820 and we know <em>master</em> matches <em>revert-c99</em> exactly.  In fact:</p></div>
  821 <div class="listingblock">
  822 <div class="content">
  823 <pre><code>$ git diff master..revert-c99</code></pre>
  824 </div></div>
  825 <div class="paragraph"><p>says nothing.</p></div>
  826 <div class="paragraph"><p>Then we rebase the <em>pu</em> branch as usual.</p></div>
  827 <div class="listingblock">
  828 <div class="content">
  829 <pre><code>$ git checkout pu
  830 $ git tag pu-anchor pu
  831 $ git rebase master
  832 * Applying: Redo "revert" using three-way merge machinery.
  833 First trying simple merge strategy to cherry-pick.
  834 * Applying: Remove git-apply-patch-script.
  835 First trying simple merge strategy to cherry-pick.
  836 Simple cherry-pick fails; trying Automatic cherry-pick.
  837 Removing Documentation/git-apply-patch-script.txt
  838 Removing git-apply-patch-script
  839 * Applying: Document "git cherry-pick" and "git revert"
  840 First trying simple merge strategy to cherry-pick.
  841 * Applying: mailinfo and applymbox updates
  842 First trying simple merge strategy to cherry-pick.
  843 * Applying: Show commits in topo order and name all commits.
  844 First trying simple merge strategy to cherry-pick.
  845 * Applying: More documentation updates.
  846 First trying simple merge strategy to cherry-pick.</code></pre>
  847 </div></div>
  848 <div class="paragraph"><p>The temporary tag <em>pu-anchor</em> is me just being careful, in case <em>git
  849 rebase</em> screws up.  After this, I can do these for sanity check:</p></div>
  850 <div class="listingblock">
  851 <div class="content">
  852 <pre><code>$ git diff pu-anchor..pu ;# make sure we got the master fix.
  853 $ make CC=gcc-2.95 clean test ;# make sure it fixed the breakage.
  854 $ make clean test ;# make sure it did not cause other breakage.</code></pre>
  855 </div></div>
  856 <div class="paragraph"><p>Everything is in the good order.  I do not need the temporary branch
  857 or tag anymore, so remove them:</p></div>
  858 <div class="listingblock">
  859 <div class="content">
  860 <pre><code>$ rm -f .git/refs/tags/pu-anchor
  861 $ git branch -d revert-c99</code></pre>
  862 </div></div>
  863 <div class="paragraph"><p>It was an emergency fix, so we might as well merge it into the
  864 <em>release candidate</em> branch, although I expect the next release would
  865 be some days off:</p></div>
  866 <div class="listingblock">
  867 <div class="content">
  868 <pre><code>$ git checkout rc
  869 $ git pull . master
  870 Packing 0 objects
  871 Unpacking 0 objects
  872 
  873 * commit-ish: e3a693c...        refs/heads/master from .
  874 Trying to merge e3a693c... into 8c1f5f0... using 10d781b...
  875 Committed merge 7fb9b7262a1d1e0a47bbfdcbbcf50ce0635d3f8f
  876  cache.h        |    8 ++++----
  877  commit.c       |    2 +-
  878  ls-files.c     |    2 +-
  879  receive-pack.c |    2 +-
  880  server-info.c  |    2 +-
  881  5 files changed, 8 insertions(+), 8 deletions(-)</code></pre>
  882 </div></div>
  883 <div class="paragraph"><p>And the final repository status looks like this:</p></div>
  884 <div class="listingblock">
  885 <div class="content">
  886 <pre><code>$ git show-branch --more=1 master pu rc
  887 ! [master] Revert "Replace zero-length array decls with []."
  888  ! [pu] git-repack: Add option to repack all objects.
  889   * [rc] Merge refs/heads/master from .
  890 ---
  891  +  [pu] git-repack: Add option to repack all objects.
  892  +  [pu~1] More documentation updates.
  893  +  [pu~2] Show commits in topo order and name all commits.
  894  +  [pu~3] mailinfo and applymbox updates
  895  +  [pu~4] Document "git cherry-pick" and "git revert"
  896  +  [pu~5] Remove git-apply-patch-script.
  897  +  [pu~6] Redo "revert" using three-way merge machinery.
  898   - [rc] Merge refs/heads/master from .
  899 ++* [master] Revert "Replace zero-length array decls with []."
  900   - [rc~1] Merge refs/heads/master from .
  901 ... [master~1] Merge refs/heads/portable from http://www.cs.berkeley....</code></pre>
  902 </div></div>
  903 </div>
  904 </div>
  905 </div>
  906 <div id="footnotes"><hr /></div>
  907 <div id="footer">
  908 <div id="footer-text">
  909 Last updated
  910  2018-12-15 13:25:21 JST
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