use Modern::Perl;
my $gen_build_man = 'C:\python.py';
open my $GENMAN, '<', $gen_build_man or die "could not open $gen_build_man - $!"; 
{
    local $/=undef;
    my $file = <$GENMAN>;    
    say 'genman.pl not found in the file' unless $file =~ /genman\.pl/;
}