#!/usr/bin/perl -w

use strict;
use warnings;

my $condition = 0;

sub RunProg   # Run program only if it exists
{
  my $CMD = join(' ', @_);
  my $PRG = ($CMD =~ m/^([a-zA-Z0-9_\/\-.~!]+)/) ? $1 : '';
  if (length(`which $PRG`)) { return system("$CMD"); }
  return -1;
}

my @args = ('yad --help');

my $RET = eval(($condition ? 'system' : 'RunProg') . '(@args);' );
print "\nRETURN VALUE = $RET\n";