I updated the script to be able to run in parallel with multiple processes

Added PID number for temporary files, that the script can run in parallel with multiple processes.
Added a check if one arguments is defined at script startup.
Note: The script requires wget to be installed at /usr/bin/.
So I updated the source code, here is my version:
#!/usr/bin/perl
# (C) Unknown author at http://localhost/directory/Plugins/Websites%2C-Forms-and-Transactions/check_url/details
#
# Changes:
# 2016-01-07: Stephan Ferraro
# Added PID number for temporary files, that the script can run in parallel with multiple processes.
# Added a check if one arguments is defined at script startup. — Stephan Ferraro

use strict;

if ($#ARGV == -1)
{
print STDERR “usage: check_url.pl URLn”;
exit 1;
}

my $wget = ‘/usr/bin/wget –output-document=/tmp/tmp_’.$$.’.html –no-check-certificate -S’;
my ($url) = @ARGV;
my @OK = (“200”);
my @WARN = (“400”, “401”, “403”, “404”, “408”);
my @CRITICAL = (“500”, “501”, “502”, “503”, “504”);

my $TIMEOUT = 20;

my %ERRORS = (‘UNKNOWN’ , ‘-1’,
‘OK’ , ‘0’,
‘WARNING’, ‘1’,
‘CRITICAL’, ‘2’);

my $state = “UNKNOWN”;
my $answer = “”;

$SIG{‘ALRM’} = sub {
print (“ERROR: check_url Time-Out $TIMEOUT s n”);
exit $ERRORS{“UNKNOWN”};
};
alarm($TIMEOUT);

system (“$wget $url 2>/tmp/tmp_”.$$.”.res1″);

if (! open STAT1, “/tmp/tmp_”.$$.”.res1″) {
print (“$state: $wget returns no result!”);
exit $ERRORS{$state};
}
close STAT1;

`cat /tmp/tmp_$$.res1|grep ‘HTTP/1’|tail -n 1 >/tmp/tmp_$$.res`;
open (STAT, “/tmp/tmp_”.$$.”.res”);
my @lines = ;
close STAT;

if ($lines[0]=~/HTTP/1.d+ (d+)( .*)/) {
my $errcode = $1;
my $errmesg = $2;

$answer = $answer . “$errcode $errmesg”;

if (‘1’ eq &chkerrwarn($errcode) ) {
$state = ‘WARNING’;
} elsif (‘2’ eq &chkerrcritical($errcode)) {
$state = ‘CRITICAL’;
} elsif (‘0’ eq &chkerrok($errcode)) {
$state = ‘OK’;
}
}

sub chkerrcritical {
my $err = $1;
foreach (@CRITICAL){
if ($_ eq $err) {
return 2;
}
}
return -1;
}

sub chkerrwarn {
my $err = $1;
foreach (@WARN){
if ($_ eq $err) {
return 1;
}
}
return -1;
}

sub chkerrok {
my $err = $1;
foreach (@OK){
if ($_ eq $err) {
return 0;
}
}
return -1;
}

`rm /tmp/tmp_$$.html /tmp/tmp_$$.res /tmp/tmp_$$.res1`;

print (“$state: $answern”);
exit $ERRORS{$state};