you could just check for it before. 
#!/usr/bin/perl
$argument = $ARVG[0] || warn "No argument";
print "argv = |$ARVG[0]|\n"; 
if ($argument !=~/\w/ ) {
    print "enter an argument \n";
    chomp ($argument = <STDIN>);
}

[download]

.... or something like that. in the reg ex you could even check for the right type of input.

update
thanks to tadman for pointing out this, but I was missing an equals sign in the above.. also, got a cup of coffee in me and fixed other silly stuff.. sorry for the first poor response.

In reply to Re: Command line argument by krujos
in thread Command line argument by Anonymous Monk

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