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What process has what files open?

This post was written on 2005/03/09 at 22:34:04

I think everyone knows the problem: Sometimes some process changes files while you want to play with them. Be it unmounting a device, or simply some concurrent writing. Under Linux it's fairly easy to find out what process has what file descriptors open. That's all simply stored in /proc. Now I wanted to find | grep it and ... well, I simply don't really like Bash so I wrote a small script in Perl that will print all open files with their name and the process id that has the file open: 




my $procdir = '/proc';
   opendir(PROCDIR,"/proc") or die("Can't open proc...");
   my @procs;
   while(defined($file = readdir(PROCDIR))){
       if ($file =~ /^[0-9]/) {
           if (-e '/proc/'.$file.'/fd/'){
               push @procs,$file;
           }
       }
   }
   closedir(PROCDIR);
   foreach(@procs){
       my $pid = $_;
       my $fdpath = '/proc/'.$_."/fd/";
       opendir(DIR,$fdpath);
       while(defined($file = readdir(DIR))){
           if (-l $fdpath.$file){
               if(defined($act = readlink($fdpath.$file))){
                   if ($act =~ /^//){
                       print "[PID:$pid]",$act,"n";
                   }
               }
           }
       }
       closedir(DIR);
   }

Perhaps someone else will find this useful :-) It's not fast, it's not nice, but it does the job :-)

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