Hello All,
On some purpose I wrote two small programs start.cgi and server.cgi:

start.cgi 
#!/usr/bin/perl -w

open(PID, "< pid") || die "Can't open PID file: $!";
$pid = <PID>;
close PID;
if(defined $pid){
   if($pid==0){
#       print "Location: http://test/test.html \n\n";
       print "Content-type: text/html\n\n";
       print "<html>hello<html>";    
       exec '/usr/sites/test/vcgi/server.cgi';
   }
}

[download]
server.cgi 
#!/usr/bin/perl -w

#  use IO::Socket;
open(PID, "> pid") || die "Can't open PID file: $!";
print PID $$ ;
close PID;

[download]
Both programs and pid file are located at '/usr/sites/test/vcgi' which is set as 'cgi-bin' dir in Apache config file. Start.cgi is executed from a browser. It checks if server.cgi is on (reading pid file) runs it if it's not and returns 'hello'. At the beginning pid file contains '0'. test.html page contains nothing but html and body tags

The problem.
Programs work fine until I remove comments from 'use..' statement in server.cgi OR replace two print statements with 'Location...' one in start.cgi.
If I do any of those server.cgi writes nothing into pid and I'm not sure if it's executed at all.
If I run start.cgi from shell everything works fine with 'use..' and 'Location...'.
I don't undertand this at all and will be appreciated if anyone tell me where the source of this problem might be.
Thank you.

In reply to CGI problems - please help by alikim

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