How can I prevent more than one instance of a script from running?
I use flock -n "$0" true || exit 1 in some of my shell scripts that need locking (i.e. check whether the script itself has an advisory lock on it). The same could be implemented in Perl: 
use FindBin qw($Bin $Script);
use Fcntl ':flock';

open my $fh, '>>', "$Bin/$Script" or die "open(>>$Bin/$Script): $!";
flock $fh, LOCK_EX|LOCK_NB or die "Another copy seems to be running";

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The >> mode may be required depending on how flock is implemented (you may get by with just <). Alternatively, remove |LOCK_NB to make your process wait until it has the lock instead of terminating. Lock is automatically removed when the owning process terminates, so no need to manually unlock anything.

In reply to Re: Preventing multiple instances by Anonymous Monk
in thread Preventing multiple instances by Bod

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