defaria.com/blogs/Status/2005/11/forking-in-perl.html

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   5     <meta name="description" content=" Continued to help several users with connecting to the new Controller Clearquest Database for Vinh's users Added Version Tree button to the bin_merge prompt dialog box. Resolved problem with forking from PerlTk...">
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  26     <meta property="og:description" content=" Continued to help several users with connecting to the new Controller Clearquest Database for Vinh's users Added Version Tree button to the bin_merge prompt dialog box. Resolved problem with forking from PerlTk...">
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  30     <meta itemprop="description" content=" Continued to help several users with connecting to the new Controller Clearquest Database for Vinh's users Added Version Tree button to the bin_merge prompt dialog box. Resolved problem with forking from PerlTk...">
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  70                   <h2 itemprop="name" class="asset-name entry-title">Forking in PerlTk</h2>
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  73                       <li class="asset-meta-list-item">Posted on <time datetime="2005-11-23T13:59:39-08:00" itemprop="datePublished">November 23, 2005</time></li>
  74                       <li class="asset-meta-list-item">by <span class="author entry-author vcard"></span></li>
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  84                   <ul>
  85   <li>Continued to help several users with connecting to the new Controller Clearquest Database for Vinh's users</li>
  86
  87   <li>Added Version Tree button to the bin_merge prompt dialog box.</li>
  88
  89   <li>Resolved problem with forking from PerlTk</li>
  90 </ul>
  91                   <h2>Forking in PerlTk</h2>
  92
  93 <p>The issue here is that calling fork(2) in general on Windows just doesn't work well. Clearcase's Perl is based on ActiveState Perl and ActiveState Perl is not the best implementation of Perl. Cygwin's Perl is by far a much better implementation but Cygwin's Perl works from a true Posix environment which is specifically what Cygwin is all about. However Cygwin's Perl does not support PerlTk (I posted on Cygwin's mailing list about this - it would be great if Cygwin would finally support PerlTk) and Cygwin would need to be present on all Windows systems.</p>
  94
  95 <p>In general, while fork(2) does work under ActiveState is does not work if you have Tk objects created. Chris had suggested to use "start &lt;program&gt;" which is fine - for Windows - but would fail in Unix. I like to wrote my code such that it works on both Windows and Unix. So I tried in vain to get fork to work. However, ActiveState's fork(2) call is horribly broken so I had to code around it like this:</p>
  96
  97 <div class="code"><pre>
  98 sub VersionTree {
  99   my $file = shift;
 100
 101   my $cmd =  "cleartool lsvtree -graphical $file";
 102
 103   if ($^O =~ /mswin|cygwin/i) {
 104     system "start /b $cmd";
 105   } else {
 106     my $pid = fork;
 107
 108     return if $pid;
 109
 110     system $cmd;
 111     exit;
 112   } # if
 113 } # VersionTree
 114 </pre></div>
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