I haven't used a hex-editor in decades. This is one of the few times where I still use Perl instead of Python. $ perl -i.bak -p0777e \ 'print STDE

I haven't used a hex-editor in decades. This is one of the few times where I still use Perl instead of Python. $ perl -i.bak -p0777e \ 'print STDERR s/\xe4\x0a\x00\x2d/\xde\xad\xbe\xef/g + 0 . "\n"' a.out 1 $ cmp -l a.out.bak a.out 50161 344 336 50162 12 255 50163 0 276 50164 55 357 $ Perl prints the number of substitutions done. If it's 1, all's well.