my %var = (FOO => 'bar'); open my $fh, '+<', $file or die $!; read $fh => my $text, -s $fh; $text =~ s/__([A-Z]+)__/$var{$1}/g; seek $fh, 0, 0; print $fh $text; truncate $fh, tell; close $fh;
open my $sfh, '<', $src_file or die $!; open my $tfh, '>', $tmp_file or die $!; while (<$sfh>) { s/__([A-Z]+)__/$var{$1}/g; print $tfh $_; } close $tfh and close $sfh or die $!; rename $tmp_file => $src_file or die $!;
