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chromium / external / gitster / git-htmldocs / 93362779d752f73554b3a0b117fda497b5e64b90 / . / git-update-ref.html
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Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]306</style>
307<title>git-update-ref(1)</title>
308</head>
309<body>
310<div id="header">
311<h1>
312git-update-ref(1) Manual Page
313</h1>
314<h2>NAME</h2>
315<div class="sectionbody">
316<p>git-update-ref -
Junio C Hamano7c73c662007-01-19 00:37:50[diff] [blame]317 Update the object name stored in a ref safely
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]318</p>
319</div>
320</div>
321<h2>SYNOPSIS</h2>
322<div class="sectionbody">
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]323<div class="para"><p><em>git update-ref</em> [-m &lt;reason&gt;] (-d &lt;ref&gt; [&lt;oldvalue&gt;] | [--no-deref] &lt;ref&gt; &lt;newvalue&gt; [&lt;oldvalue&gt;])</p></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]324</div>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]325<h2 id="_description">DESCRIPTION</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]326<div class="sectionbody">
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]327<div class="para"><p>Given two arguments, stores the &lt;newvalue&gt; in the &lt;ref&gt;, possibly
Junio C Hamanofce7c7e2008-07-02 03:06:38[diff] [blame]328dereferencing the symbolic refs. E.g. <tt>git update-ref HEAD
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]329&lt;newvalue&gt;</tt> updates the current branch head to the new object.</p></div>
330<div class="para"><p>Given three arguments, stores the &lt;newvalue&gt; in the &lt;ref&gt;,
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]331possibly dereferencing the symbolic refs, after verifying that
332the current value of the &lt;ref&gt; matches &lt;oldvalue&gt;.
Junio C Hamanofce7c7e2008-07-02 03:06:38[diff] [blame]333E.g. <tt>git update-ref refs/heads/master &lt;newvalue&gt; &lt;oldvalue&gt;</tt>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]334updates the master branch head to &lt;newvalue&gt; only if its current
Junio C Hamanoa2ec14f2006-11-02 00:22:48[diff] [blame]335value is &lt;oldvalue&gt;. You can specify 40 "0" or an empty string
336as &lt;oldvalue&gt; to make sure that the ref you are creating does
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]337not exist.</p></div>
338<div class="para"><p>It also allows a "ref" file to be a symbolic pointer to another
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]339ref file by starting with the four-byte header sequence of
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]340"ref:".</p></div>
341<div class="para"><p>More importantly, it allows the update of a ref file to follow
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]342these symbolic pointers, whether they are symlinks or these
343"regular file symbolic refs". It follows <strong>real</strong> symlinks only
344if they start with "refs/": otherwise it will just try to read
345them and update them as a regular file (i.e. it will allow the
346filesystem to follow them, but will overwrite such a symlink to
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]347somewhere else with a regular filename).</p></div>
348<div class="para"><p>If --no-deref is given, &lt;ref&gt; itself is overwritten, rather than
349the result of following the symbolic pointers.</p></div>
350<div class="para"><p>In general, using</p></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]351<div class="literalblock">
352<div class="content">
Junio C Hamanofce7c7e2008-07-02 03:06:38[diff] [blame]353<pre><tt>git update-ref HEAD "$head"</tt></pre>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]354</div></div>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]355<div class="para"><p>should be a _lot_ safer than doing</p></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]356<div class="literalblock">
357<div class="content">
358<pre><tt>echo "$head" &gt; "$GIT_DIR/HEAD"</tt></pre>
359</div></div>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]360<div class="para"><p>both from a symlink following standpoint <strong>and</strong> an error checking
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]361standpoint. The "refs/" rule for symlinks means that symlinks
362that point to "outside" the tree are safe: they'll be followed
363for reading but not for writing (so we'll never write through a
364ref symlink to some other tree, if you have copied a whole
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]365archive by creating a symlink tree).</p></div>
366<div class="para"><p>With <tt>-d</tt> flag, it deletes the named &lt;ref&gt; after verifying it
367still contains &lt;oldvalue&gt;.</p></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]368</div>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]369<h2 id="_logging_updates">Logging Updates</h2>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]370<div class="sectionbody">
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]371<div class="para"><p>If config parameter "core.logAllRefUpdates" is true or the file
Junio C Hamanofce7c7e2008-07-02 03:06:38[diff] [blame]372"$GIT_DIR/logs/&lt;ref&gt;" exists then <tt>git update-ref</tt> will append
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]373a line to the log file "$GIT_DIR/logs/&lt;ref&gt;" (dereferencing all
374symbolic refs before creating the log name) describing the change
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]375in ref value. Log lines are formatted as:</p></div>
376<div class="olist"><ol>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]377<li>
378<p>
379oldsha1 SP newsha1 SP committer LF
380</p>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]381<div class="para"><p>Where "oldsha1" is the 40 character hexadecimal value previously
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]382stored in &lt;ref&gt;, "newsha1" is the 40 character hexadecimal value of
383&lt;newvalue&gt; and "committer" is the committer's name, email address
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]384and date in the standard GIT committer ident format.</p></div>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]385</li>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]386</ol></div>
387<div class="para"><p>Optionally with -m:</p></div>
388<div class="olist"><ol>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]389<li>
390<p>
391oldsha1 SP newsha1 SP committer TAB message LF
392</p>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]393<div class="para"><p>Where all fields are as described above and "message" is the
394value supplied to the -m option.</p></div>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]395</li>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]396</ol></div>
397<div class="para"><p>An update will fail (without changing &lt;ref&gt;) if the current user is
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]398unable to create a new log file, append to the existing log file
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]399or does not have committer information available.</p></div>
Junio C Hamano341071d2006-06-04 07:24:48[diff] [blame]400</div>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]401<h2 id="_author">Author</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]402<div class="sectionbody">
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]403<div class="para"><p>Written by Linus Torvalds &lt;torvalds@osdl.org&gt;.</p></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]404</div>
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]405<h2 id="_git">GIT</h2>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]406<div class="sectionbody">
Junio C Hamano4604fe52008-09-19 06:37:10[diff] [blame]407<div class="para"><p>Part of the <a href="git.html">git(1)</a> suite</p></div>
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]408</div>
409<div id="footer">
410<div id="footer-text">
Junio C Hamanofa2ad882009-12-03 09:15:44[diff] [blame]411Last updated 2009-12-03 09:12:51 UTC
Junio C Hamano1a4e8412005-12-27 08:17:23[diff] [blame]412</div>
413</div>
414</body>
415</html>