use feature qw(say switch);

given($ARGV[1]) {
    when ('-SMC') { $cust= 'SMC';  }
    when ('-FET') { $cust= 'FET''; }
     # .... add other conditions ...
     # You can even use Regular expressions (Smart match) here, if necessary like:::
    when (/china/i) {$cust='China';}

    default  { say 'Invalid customer'; }
}