#!/usr/bin/env perl
use strict;
use warnings;
use utf8;

my $name;
my $group;
my $useraddcmd;
my $password;
my $passwdcmd;

$name = getprop_must("enter username:");
$group = getprop_opt("enter usergroup(default '$name'):");
$useraddcmd = "useradd " . ($group ? " -g $group " : " ") . $name;
system($useraddcmd) == 0 || die;

$password = getprop_must("enter password for $name:");
$password eq getprop_must("re-enter password for $name:") || die("error: password mismatch.");
$passwdcmd = "yes $password | passwd $name > /dev/null 2>&1";
system($passwdcmd);

sub getprop_opt {
        my $prompt = shift;
        my $prop;

        print $prompt . $/;
        $prop = <STDIN>;
        $prop =~ s/^\s*([^\s]*)\s*$/$1/;
        return $prop;
}

sub getprop_must {
        my $prompt = shift;
        my $prop;
        do {
                $prop = getprop_opt($prompt);
        } while (!$prop);
        return $prop;
}