Here is a basic template. There is a Net::SNMP module you can probably use. It is OO and well documented.

[root@devel3 root]# cat test.pl
#!/usr/bin/perl -w

use strict;

my @progs = qw(
    squid
    cleaner.pl
    httpd
    noexist.php
);

for my $prog( @progs ) {
    if ( `ps -C $prog` =~ m/\Q$prog\E/ ) {
        print "Found $prog\n";
    }
    else {
        do_warn($prog);
    }
}

sub do_warn {
    my $prog = shift;
    warn "$prog is not up, typical!\n";
}
[root@devel3 root]# ./test.pl
Found squid
Found cleaner.pl
Found httpd
noexist.php is not up, typical!
[root@devel3 root]#
[download]