using IPC::Cmd I am writing a nagios check that will warn whenever one of the systemd services is not running. 

use IPC::Cmd qw[can_run run run_forked];
my $cmd = "systemctl --failed --no-legend";
                                          
my ( $success, $error_message, $full_buf, $stdout_buf, $stderr_buf ) =
  run( command => $cmd, verbose => 0 );
                                              
if ($success) {
    my $nr_els = @$full_buf;
    if ( $nr_els == 0 ) {
        print "OK: all systemd units in their desired state\n";
    }
    else {
        print "WARNING: ";
        print "$nr_els systemd units not running\n"; 
        for (@$full_buf) {
            print "$_\n";
        }
    } 
}

[download]
Quite straight forward. I have killed -9 (yes, with signal 1 or 15 then they are not in a failed state, you need to really kill them) two services and then I run this and get this: 
WARNING: 1 systemd units not running
avahi-daemon.service loaded failed failed Avahi mDNS/DNS-SD Stack
packagekit.service   loaded failed failed PackageKit Daemon

[download]
Why do I get '1' instead of 2? When looping throught the elements of @$full_buf I get two lines of text, so I should also get '2' in $nr_els but I get '1'. 

I must be missing something very basic ..., but I cannot see it. Thanks for your input!




 
 


In reply to number of elements in array ref wtf
by natxo





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