For extra fun, there are (or at least were) multiple implementations of the mail command. The arguments were similar enough, but an old (and replaced) system at a previous employer required Heirloom mail/snail, not BSD because it actually intentionally used escape sequences like this.<p>In particular, it used one to add attachments (by giving the path).<p>We replaced it with Perl, getting rid of the shell script entirely (the whole stack was Perl).<p>Shell scripts really ought to use the sendmail command to send mail, but then you have to remember those obscure options to pass and generate the mail headers yourself, so it's understandable why no one does. (And probably handle dot-doubling).