> -----Original Message-----
> From: Theuerkorn Johannes [mailto:[EMAIL PROTECTED]]
> Sent: 30 September 2002 10:18
> To: '[EMAIL PROTECTED]'
> Subject: how to know weather perl script is already running?
>
>
> Hello List,
>
> i have a perl script that i have running from a cron Job. It
> usually opens every 4 hours. But sometimes it takes the
> script longer to execute its job so after cron opens up the
> perl script as usual, i have two perl jobs running.
> Is there any possibility to check weather the script is
> already running? Maybe i can use a system command in the crontab?
>
> any help welcoe
>
> greets Johannes
>
> --
We use the following subs to do this on Linux:
example call:
# In your main program:
# This will exit 0 if there are no available instances
my $instance = getInstance("reporter",3); # maximum of 3 reporters
#
------------------------------------------------------------------------
-----
# Get an instance name and lock
# Used to control the maximum number of instances for a specified
process
# e.g. reporter.pl
sub getInstance {
my $name = shift;
my $max = shift;
my $msg = '';
$max ||= 1;
$msg ||= "No available instances for '$name' [maximum $max already
locked]";
my $locked = '';
foreach my $instance ( 1..$max ) {
my $token = "$name$instance";
$locked = $token if lockToken($token);
last if $locked;
}
# Note that we die gracefully
print "\n$msg\n" unless $locked;
exit 0 unless $locked;
return $locked;
}
#
------------------------------------------------------------------------
-----
sub lockToken {
my $token = shift;
mkdir "/var/lock" unless -d "/var/lock";
mkdir "/var/lock/mylocks" unless -d "/var/lock/mylocks";
my $token_file = "/var/lock/mylocks/$token";
open(FH, ">$token_file") ||
LogFatal("Cannot open token locking file '$token_file' for writing:
$OS_ERROR");
# Return success or failure depending on whether we can exclusively
lock the file
return flock(FH, LOCK_EX | LOCK_NB);
}
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