5 Responses to “Perl to check a process is running”

1. Rob on September 12th, 2006 4:55 pm

   Wow that’s super cool dude!

   Would be great for some of the things we use here at work!

2. iSheep on September 14th, 2006 4:46 pm

   This is a handy Perl module to check to see if a drive is mounted. This is done via the proc filesystem which is available on all flavours of linux

   Usage: CheckMount::isMounted({ mount => $srcMount });

   
   package CheckMount;
   
   #
   # Checks the Proc Filesystem for a mounted mount point
   # Returns 1 if the mount point is mounted else 0
   #
   
   sub isMounted{
           my $argsHash = shift;
   
           # Mount point to check
           my $checkThisMount = $argsHash->{mount};
   
           # Proc filesystem which tracks current mounts
           # This shouldn't change (on linux)
           my $procMountFile = '/proc/mounts';
   
           # Open the proc mount file
           open(FILE,"){
                   chomp();
                   push(@lineAry,$_);
           }
           close(FILE);
   
           # Parse the proc mount file
           my @mountAry = ();
           foreach my $line(@lineAry){
                   my @tmp = split(/\s/,$line);
                   push(@mountAry,\@tmp);
           }
   
           # Look for the mount point
           foreach my $mount(@mountAry){
                   my $tmp = $mount->[1];
                   if ($tmp =~ /^$checkThisMount$/){
                           # The mount is found
                           return 1;
                   }
           }
   
           # Default to mount NOT found
           return 0;
   }
   
   1;
   

3. WalterK on September 11th, 2007 4:45 am

   Thanks for the handy tip to see if something’s mounted, here is a simple alternative along with usage:

   #!/usr/bin/perl
   #
   # Checks the Proc Filesystem for a mounted mount point
   # Returns 1 if the mount point is mounted else 0
   #

   sub mountedOn{
   $checkThisMount = shift;
   # Proc filesystem which tracks current mounts
   # This shouldn’t change (on linux)
   my $procMountFile = ‘/proc/mounts’;
   # Open the proc mount file
   open(FILE, “$procMountFile”);
   while () {
   chomp();
   if (/$checkThisMount /){
   @mnt=split / /;
   return @mnt[1];
   close(FILE);
   }
   }
   close(FILE);
   # Default to mount NOT found
   return 0;
   }

   if (mountedOn(”/dev/sda1″)){
   print mountedOn(”/dev/sda1″) . “\n\n”;
   }else{
   print “Not Mounted\n”;
   }
   if (mountedOn(”/dev/sdb1″)){
   print “Mounted\n”;
   }else{
   print “Not Mounted\n”;
   }

4. Josh on January 28th, 2009 7:30 pm

   Thanks a lot for this script! I’ve been having issues with apache and sendmail crashing and wanted to cron a script to make sure they were always running. I used your script as a base and extended it to allow checking of multiple processes and added a logging feature as well. Hopefully it helps someone out!

   #!/usr/bin/perl

   use strict;

   #——————————————————————————————-
   #
   # Customize these variables
   #

   # Set whether an action (i.e. system command) should be taken if a process is found to not be running.
   # NOTE: Logging is determined solely by the logging variable (i.e. logging still happens if live is 0)

   my $live = 1;

   # Name of processes to make sure are running, along with commands to execute if they aren’t

   my %processes = (
   “apache2″, “/etc/init.d/apache2 start”,
   “idontexist”, “some command to run”,
   “sendmail-mta”, “/etc/init.d/sendmail start”
   );

   # Enable/disable logging the results of this script

   my $logging = 1;
   my $logfile = “/var/log/syschk.log”;

   # Verbosity of logs:
   # 0 -> only write to log when a process is not found
   # 1 -> write to log for each process that’s checked, regardless of whether it’s found or not.

   my $verbose = 1;

   #——————————————————————————————-

   if ( $logging ) { open FILE , “>>”.$logfile; }

   # Declare some variables
   my $sec = shift;
   my $min = shift;
   my $hour = shift;
   my $mday = shift;
   my $mon = shift;
   my $year = shift;
   my $wday = shift;
   my $yday = shift;
   my $isdst = shift;
   my $datetime = shift;
   my $process = shift;
   my $command = shift;
   my $foundProcess = 0;

   while (($process, $command) = each(%processes)) {

   ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime(time);
   $datetime = sprintf( “%4d-%02d-%02d %02d:%02d:%02d: “, $year+1900,$mon+1,$mday,$hour,$min,$sec );
   if ( $logging ) { logit( $datetime ); }
   if ( $logging && $verbose > 0 ) { logit( “Checking “.$process.”… ” ); }

   $foundProcess = 0;

   my $cmd = “ps -A | grep ” . $process;
   my $result = `$cmd`;
   my @pslines = split(”\\n”, $result);

   foreach ( @pslines ) {
   #ignore results for the grep command and this script
   unless ($_ =~ m/grep|syschk/){
   $foundProcess = 1;
   }
   }

   if ( $foundProcess == 0 ) {
   if ( $live ) { system ( $command ); }
   if ( $logging ) { logit( $process.” not running! ” ); }
   if ( $logging && $live ) { logit ( “Executing: “.$command ); }
   if ( $logging ) { logit ( “\n” ); }
   }
   else {
   # Things to do if the process was found (e.g. logs)
   if ( $logging && $verbose > 0 ) { logit( “Found “.$process.” running.\n” ); }
   }
   }

   if ( $logging ) { close FILE; }

   sub logit{
   if ($logging){
   if ( -w $logfile ) {
   print FILE “$_[0]”;
   }
   }
   }

5. Tim on June 30th, 2009 6:55 am

   Great set of ideas here, the mount one I particularly like, I’ve previously used checks for an existing file on the filesystem, but that is a much more elegant solution

   for checking for running processes, I quite like Proc::ProcessTable for the large amount of info it allows you to match on, I currently use the below sub in a number of systems for checking if a process is running, and to return the PID to start/stop said process from a web UI

   sub check_status {
   ## find process ID and return running or stopped
   use Proc::ProcessTable;
   my ($user, $procname, $path) = @_;
   my $uid = getpwnam($user);

   my $t = new Proc::ProcessTable;
   foreach my $p (@{$t->table}) {
   if ($p->{’cwd’} =~ /$path/ && $p->{’uid’} =~ /$uid/ && $p->{’cmdline’} =~ $procname) {
   return $p->{’pid’};
   }
   }
   return 0;
   }

   ### Usage

   my $html = (&check_status($d->{’user’}, ’srcds_i’, $server->{’install_path’}) > 0 ? qq~{’sid’}”>Stop~ : qq~{’sid’}”>Start~,);

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