Add & Remove entries from crontab

Add Entry : 

system ( "crontab -l > oldcrontab_$pid ; cp oldcrontab_$pid newcrontab_$pid ; echo '$min $hour $day $mon * perl /home/username/development/script.pl > /home/usrename/logs/data.log 2>&1' >> newcrontab_$pid ; crontab newcrontab_$pid; rm -f newcrontab_$pid oldcrontab_$pid");


Remove Entry : 

open my $fh, "| crontab -" || die "can't open crontab: $!";
my $cron = qx(crontab -l);
$cron =~ s!\#\*\/02 \* \* \* \* \/home\/username\/perl execute.sh > \/home\/username\/file.log 2>\&1!!;
print $fh $cron;
close $fh;