> perl -i.bak -pe "BEGIN{s!^(\s)!./$1!,s/^/</,s/$/\0/ for @ARGV} s/foo/bar/" bar
Can't open <bar: No such file or directory.

 > perl -v

This is perl, v5.10.0 built for cygwin-thread-multi-64int
(with 6 registered patches, see perl -V for more detail)

##</code><code>##

echo > '"Reason for this Perl insanity?" || rm -rf .. |'