Perl daemon

[AIXSPadmin]

Why is this not running as a daemon? It works for another script I wrote, but it does a system call to a shell script, but this is not running the dsmadmc command continuously. Any ideas? Thanks.

#!/usr/bin/perl

# load required modules
use strict;
use POSIX qw(setsid);
use POSIX qw(strftime);

# set constants
my $NodeName = `uname -n`;

# flush the buffer
$| = 1;

# daemonize the program
&daemonize;

# infinite loop
while(1) {
my $val = `dsmadmc -id=user -pass=pass "SELECT count (volume_na
me) as Scratch FROM libvolumes WHERE status='Scratch'" | tail -4 | head -1 | awk
'{print $1}'`;
if ($val eq 0) { exit 0 }
elsif ($val eq 1) { exit 1 }
elsif ($val eq 2) { exit 2 }
elsif ($val eq 3) { exit 3 }
elsif ($val eq 4) { exit 4 }
elsif ($val eq 5) { exit 5 }
else { exit 99 }
}

sub daemonize {
chdir '/' or die "Can't chdir to /: $!";
umask 0;
open STDIN, '/dev/null' or die "Can't read /dev/null: $!";
open STDERR, '/dev/null' or die "Can' write to /dev/null: $!";
defined(my $pid = fork) or die "Can't fork: $!";
exit if $pid;
setsid or die "Can't start a new session: $!";
}

 

[MikeLacey]

I've not done this in a while - but I thought you had to close STDOUT, STDIN and STDERR rather than opening just STDIN and ERR to /dev/null Mike

Want to get great answers to your Tek-Tips questions? Have a look at faq219-2884

It's like this; even samurai have teddy bears, and even teddy bears get drunk.

 

[justice41]

It's not running continuously because you explicitly tell the child to exit in this block

        if ($val eq 0) { exit 0 }
        elsif ($val eq 1) { exit 1 }
        elsif ($val eq 2) { exit 2 }
        elsif ($val eq 3) { exit 3 }
        elsif ($val eq 4) { exit 4 }
        elsif ($val eq 5) { exit 5 }
        else { exit 99 }

The child will execute your system call and then exit somewhere in this if-block. If you want it to run continuously then you will have to fork off another child inside the while-loop to execute the syscall and keep the original child alive and looping.

jaa

 

[MikeLacey]

doh! LOL

yep - whatever the return value it will exit

I still think I'm right about the close on STDOUT etc though. Mike

Want to get great answers to your Tek-Tips questions? Have a look at faq219-2884

It's like this; even samurai have teddy bears, and even teddy bears get drunk.