Anyone Know Howto Create a KeepAlive Script?

Xipher_Zero

I run Gnome-Do's Docky interface on a number of systems and occasionally it can crash. I am looking for a way to write a keep alive script that will monitor gnome-do and if it crashes restart it.

Thanks

masjoko

There are several way of fulfilling your requirement. First, your script can make use of pidof to check the pid of the command you wish to monitor. If the pid is empty, there is a possibility of the process is dead, so you run the software again.

Now, the problem is that the software is running on an X environment and the process is owned by the currently logged user. So, when you run the software again, you need to know what user privilege you are going to run the software and the display environment.

I hope my answer could give some enlightenment.

Regards,

Joko

atreyu

Xipher_Zero wrote:

I run Gnome-Do's Docky interface on a number of systems and occasionally it can crash. I am looking for a way to write a keep alive script that will monitor gnome-do and if it crashes restart it.

Thanks

I typically use a perl wrapper (i.e., daemon) for this sort of thing. The perl script starts up, detaches from the terminal, then loops indefinitely, waking up at some interval i specify to run my generic command. In your case, i might ps/pidof |grep Do Docky and relaunch it, if not running. If you're interested, i can dig up a skel of the perl daemon. the same thing can be done in bash, too, if that's more your thang.

atreyu

also see this thread
http://www.linux.com/component/fireboard/?func=view&id=16&catid=19

Xipher_Zero

atreyu wrote:

Xipher_Zero wrote:

I run Gnome-Do's Docky interface on a number of systems and occasionally it can crash. I am looking for a way to write a keep alive script that will monitor gnome-do and if it crashes restart it.

Thanks

I typically use a perl wrapper (i.e., daemon) for this sort of thing. The perl script starts up, detaches from the terminal, then loops indefinitely, waking up at some interval i specify to run my generic command. In your case, i might ps/pidof |grep Do Docky and relaunch it, if not running. If you're interested, i can dig up a skel of the perl daemon. the same thing can be done in bash, too, if that's more your thang.

Thank you! I'd really appreciate it, I am not a programmer and a skel to start from would be a great help!

Xipher_Zero

Thank you I will check it out!

atreyu

Here's the basics.

0. this is a Perl script, you have been warned

1. cut and paste this into a file called "mydaemon.pl", then edit...

2. define your sleep interval at the top of the script (my $sleepInt = ...)

3. the program it looks for is "foo.sh". substitute w/your process name.

4. it prints everything to STDOUT. you probably don't want this. ideally, they should go to a log, or be suppressed.

5. test before you run with:

perl -cw mydaemon.pl

6. let me know if you need help tweaking...

#!/usr/bin/perl
use strict;
use warnings;
use POSIX qw(setsid);
use Fcntl ':flock';
use FindBin qw($Script);

# define sleep interval here (in seconds)
my $sleepInt = 3;

# make output line-buffered
$| = 1;

# daemonize
open(SELFLOCK, "<$0") or die "couldn't open $0: $!\n";
flock(SELFLOCK, LOCK_EX | LOCK_NB) or die "another $Script is already running\n";
chdir('/') or die "can't chdir to '/': $!\n";
umask 0;
defined(my $pid = fork) || die "can't fork: $!\n";
exit if($pid);
setsid || die "can't start a new session: $!\n";

# eternal loop
while ( 1 ) {

  # do thing here...

  # eg look for pid of 'foo.sh'
  chomp(my $pid = `/sbin/pidof -x foo.sh`);
  if($pid){
    print "foo.sh (pid $pid) is running\n";
  }else{
    print "foo.sh is stopped\n";
    print "starting foo.sh...";

    # start the command
    system("foo.sh &");
  }

  print  "sleeping $sleepInt seconds...\n";
  sleep $sleepInt;
}

# you should never get here
exit(1);

Xipher_Zero

atreyu wrote:

Here's the basics.

0. this is a Perl script, you have been warned

1. cut and paste this into a file called "mydaemon.pl", then edit...

2. define your sleep interval at the top of the script (my $sleepInt = ...)

3. the program it looks for is "foo.sh". substitute w/your process name.

4. it prints everything to STDOUT. you probably don't want this. ideally, they should go to a log, or be suppressed.

5. test before you run with:

perl -cw mydaemon.pl

6. let me know if you need help tweaking...

#!/usr/bin/perl
use strict;
use warnings;
use POSIX qw(setsid);
use Fcntl ':flock';
use FindBin qw($Script);

# define sleep interval here (in seconds)
my $sleepInt = 3;

# make output line-buffered
$| = 1;

# daemonize
open(SELFLOCK, "<$0") or die "couldn't open $0: $!\n";
flock(SELFLOCK, LOCK_EX | LOCK_NB) or die "another $Script is already running\n";
chdir('/') or die "can't chdir to '/': $!\n";
umask 0;
defined(my $pid = fork) || die "can't fork: $!\n";
exit if($pid);
setsid || die "can't start a new session: $!\n";

# eternal loop
while ( 1 ) {

  # do thing here...

  # eg look for pid of 'foo.sh'
  chomp(my $pid = `/sbin/pidof -x foo.sh`);
  if($pid){
    print "foo.sh (pid $pid) is running\n";
  }else{
    print "foo.sh is stopped\n";
    print "starting foo.sh...";

    # start the command
    system("foo.sh &");
  }

  print  "sleeping $sleepInt seconds...\n";
  sleep $sleepInt;
}

# you should never get here
exit(1);

Thanks! I will work on it when I get home and let you know how it goes!