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

my $line;

while ( (print "Prompt: "), $line=<STDIN>, $line !~ /^\s*Q(uit)\s*$/i )
{
   $line =~ s/^\s*//;
   $line =~ s/\s*$//;
   
   print"xyzzy \"$line\" and nothing happens\n";
}

print "Some version of QUIT, QuIt, quit entered\n";

__END__
C:\Projects_Perl\testing>perl simplecommandline.pl
Prompt:    123
xyzzy "123" and nothing happens
Prompt: abc
xyzzy "abc" and nothing happens
Prompt:   123 abc
xyzzy "123 abc" and nothing happens
Prompt: qui
xyzzy "qui" and nothing happens
Prompt: quit doing that!
xyzzy "quit doing that!" and nothing happens
Prompt: QUiT
Some version of QUIT, QuIt, quit entered