ch18_03.htm
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<html><head><title>Basic Operation (UNIX in a Nutshell: System V Edition)</title><link rel="stylesheet" type="text/css" href="../style/style1.css" /><meta name="DC.Creator" content="Arnold Robbins" /><meta name="DC.Format" content="text/xml" scheme="MIME" /><meta name="DC.Language" content="en-US" /><meta name="DC.Publisher" content="O'Reilly & Associates, Inc." /><meta name="DC.Source" scheme="ISBN" content="1-56592-427-4" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="UNIX in a Nutshell: System V Edition" /><meta name="DC.Type" content="Text.Monograph" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Book Title" /><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch18_02.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228" /><td align="right" valign="top" width="228"><a href="ch18_04.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">18.3. Basic Operation</h2><p>This section outlines the steps to follow when using SCCS:</p><ul><li><p>Creating an SCCS file</p></li><li><p>Retrieving a file</p></li><li><p>Creating new releases and branches</p></li><li><p>Recording changes</p></li><li><p>Caveats</p></li></ul><a name="unut-ch-18-sect-2.1" /><div class="sect2"><h3 class="sect2">18.3.1. Creating an SCCS File</h3><p><a name="IXT-18-123489" />The <tt class="literal">admin</tt> command with the <tt class="literal">-i</tt> option creates and initializes SCCS files.For example:</p><blockquote><pre class="code"><tt class="userinput"><b>admin -ich01 s.ch01</b></tt></pre></blockquote><p>creates a new SCCS file and initializes it with the contents of<tt class="literal">ch01</tt>, which becomes <em class="emphasis">delta 1.1</em>.The message “No idkeywords (cm7)” appears if you do not specify any keywords. In general, “id keywords” refer to variablesin the files that are replaced with appropriate values by <tt class="literal">get</tt>,identifying the date and time of creation, the version retrieved, etc. A listing of identification keywords occurs later in this chapter.</p><p>Once the <tt class="literal">s.ch01</tt> file is created, the original <tt class="literal">ch01</tt> filecan be removed, since it can be easily regenerated with the <tt class="literal">get</tt> command.</p></div><a name="unut-ch-18-sect-2.2" /><div class="sect2"><h3 class="sect2">18.3.2. Retrieving a File</h3><p><a name="IXT-18-123490" /><a name="IXT-18-123491" /><a name="IXT-18-123492" />The <tt class="literal">get</tt> command can retrieve any version of a file from SCCS. Using the example above, you can retrieve <tt class="literal">ch01</tt>by entering:</p><blockquote><pre class="code"><tt class="userinput"><b>get -e s.ch01</b></tt></pre></blockquote><p>and the messages: </p><blockquote><pre class="code">1.1new delta 1.2272 lines</pre></blockquote><p>may appear. This indicates that you are “getting” <em class="emphasis">delta 1.1</em>,and the resulting file has 272 lines of text. When the file is<a name="IXT-18-123493" /><a name="IXT-18-123494" /><a name="IXT-18-123495" />reentered into the SCCS file <tt class="literal">s.ch01</tt> with the <tt class="literal">delta</tt> command,its changes are <em class="emphasis">delta 1.2</em>.</p><p>The <tt class="literal">-e</tt> option indicates to SCCS that you intend to make more changes to the file and then reenter it into SCCS. Without this option, you will receive the file with read-only permissions.The <tt class="literal">-e</tt> option, besides releasing the file with read-write permissions, also creates a file <tt class="literal">p.ch01</tt>, which records information that is used by SCCS when the file is returned.</p></div><a name="unut-ch-18-sect-2.3" /><div class="sect2"><h3 class="sect2">18.3.3. Creating New Releases and Branches</h3><p>The <tt class="literal">-r</tt> option to <tt class="literal">get</tt> tells SCCS what release andlevel number you want, but if no level is specified, it defaultsto the highest level available. With the command:</p><blockquote><pre class="code"><tt class="userinput"><b>get -r3.2 ch01</b></tt></pre></blockquote><p>delta 3.2 is the release. However, the command:</p><blockquote><pre class="code"><tt class="userinput"><b>get -r3 ch01</b></tt></pre></blockquote><p>returns the highest-numbered level in release 3,for example, <tt class="literal">3.8</tt>. With the <tt class="literal">-r</tt>option omitted, <tt class="literal">get</tt> defaults to the highest release,highest level--in other words, the latest version.</p><p>When major changes are in store for a file, you may want to begin a newrelease of the file by “getting” the file with thenext highest release number. For example, if the latest release ofa file is 3.2, and you want to start release 4, enter:</p><blockquote><pre class="code"><tt class="userinput"><b>get -e -r4 ch01</b></tt></pre></blockquote><p>You receive the message:</p><blockquote><pre class="code">3.2new delta 4.153 lines</pre></blockquote><p>If you want to make a change to an older version of the same file, you canenter:</p><blockquote><pre class="code"><tt class="userinput"><b>get -e -r2.2 ch01</b></tt></pre></blockquote><p>and receive the message:</p><blockquote><pre class="code">2.2new delta 2.2.1.1121 lines</pre></blockquote><p>You have now created a new branch from the trunk, stemming fromversion 2.2. Changes in this deltawill not affect those in the trunk deltas, i.e., 2.3, 3.1, etc.</p></div><a name="unut-ch-18-sect-2.4" /><div class="sect2"><h3 class="sect2">18.3.4. Recording Changes</h3><p>Once changes have been made to the SCCS file, return it to SCCS with:</p><blockquote><pre class="code"><tt class="userinput"><b>delta s.ch01</b></tt></pre></blockquote><p>You are prompted for comments on the changes. The <tt class="literal">delta</tt><a name="IXT-18-123496" />command then does its own <tt class="literal">get</tt> and uses <tt class="literal">diff</tt> to compare the new version of the file with the most recent version.It then prints messages giving the new release numberand the number of lines that were inserted, deleted, and unchanged.</p></div><a name="unut-ch-18-sect-2.5" /><div class="sect2"><h3 class="sect2">18.3.5. Caveats</h3><p>Here are some things to bear in mind when using SCCS:</p><ul><li><p>You can't store binary data in an SCCS file.Solaris SCCS allows it by encoding the file using <tt class="literal">uuencode</tt>.</p></li><li><p>SCCS doesn't preserve the execute bit from the file permissions offiles checked into it. This is important particularly for shellscripts: you have to explicitly make them executable after retrievingthem from SCCS. This should be automated using <tt class="literal">make</tt>.</p></li><li><p>Using ID keywords (see the next section) inyour <em class="emphasis">printf</em>(3S) format strings can lead todisaster. Find some indirect way to generate these strings for printing.</p></li></ul></div><hr width="684" align="left" /><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch18_02.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch18_04.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">18.2. Overview of Commands</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">18.4. Identification Keywords</td></tr></table></div><hr width="684" align="left" /><img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" /><p><p><font size="-1"><a href="copyrght.htm">Copyright © 2003</a> O'Reilly & Associates. All rights reserved.</font></p><map name="library-map"><area shape="rect" coords="1,0,88,96" href="../index.htm"><area shape="rect" coords="90,0,165,96" href="../upt/index.htm"><area shape="rect" coords="168,1,253,107" href="../mac/index.htm"><area shape="rect" coords="255,0,335,97" href="../korn/index.htm"><area shape="rect" coords="337,0,415,109" href="../unixnut/index.htm"><area shape="rect" coords="417,0,512,122" href="../sedawk/index.htm"><area shape="rect" coords="514,0,605,105" href="../lunix/index.htm"><area shape="rect" coords="611,2,694,121" href="../vi/index.htm"></map></body></html>⌨️ 快捷键说明
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