#!/usr/bin/perl
# vi:ts=4 sw=4 et:
use strict;
use warnings;

print "continue [y/N]? ";
chomp ( my $answer = <STDIN> );

# any other answer than 'y' or 'Y' results in an termination of the program
if ( $answer !~ m/[Yy]/ ) {
    exit 0;
}

# process first
foo( 'foo.txt' );

sub foo {
    my $file = shift;

    print "work with '$file'\n";

    print "continue [y/N]? ";
    chomp( $answer = <STDIN> );

    if ( $answer !~ m/[yY]/ ) {
        exit 0;
    }

    print "change what? ";
    chomp( my $to_change = <STDIN> );

    if ( defined $to_change ) {
        print "wanted to change: $to_change\n";
    }
 
    print "again [Y/n]? ";
    chomp( $answer = <STDIN> );

    if ( $answer !~ m/[Yy]/ ) {
        exit 0;
    }

    print "running again: \n";
    # process second
    foo( 'bar.txt' );
}