my $SUCCESS = 0;
my %Error   = ( q[No such file or directory] => 1 );

my @out = qx { command here 2>&1 };
my $rc = $?;

if ( $rc == $SUCCESS )
{
  #  As I wrote earlier, if command was sucessful, then why would
  #  there be no-file-found error (under normal conditions)? Else,
  #  exit code cannot be trusted.
  ... = grep { $Error{$_} } @out;
  ...
}
...