RE: :r modifier

["Andrej Borsenkow" <Andrej.Borsenkow@mow.siemens.ru>]

>
>           No, under some older flavors of Unix, leading `//' is a
>           special path name: it refers to a "super-root" and is used to
>           access other machines' files.  Leading `///', `////', etc.
>           are equivalent to `/'; but leading `//' is special.  I think
>           this tradition started with Apollo Domain/OS, an OS that is
>           still in use on some older hosts.
>

I really liked Apollo Domain/OS. It was nice system, with transparent
networking, remote execution and file system. You could start program on a
second system with input from local (your own) and let output be created on a
third.

>           POSIX.2 allows but does not require the special treatment for
>           `//'.  It says that the behavior of dirname on path names of
>           the form `//([^/]+/*)?'  is implementation defined.  In these
>           cases, GNU `dirname' returns `/', but it's more portable to
>           return `//' as this works even on those older flavors of Unix.
>

Yep, POSIX is very careful to not require changing of existing behaviour. It
prefers to leave most things as implementation defined.

>
>  Andrej> I checked bash and it behaves the same as zsh.
>
> Huh?  You aren't speaking about :h here, are you?
>

I am speaking about :r and :e. What so special about :h? Here is bash:

mw1g017@MW1G17C ~
$ ls  /bar/bar.baz/baz
ls: /bar/bar.baz/baz: No such file or directory

mw1g017@MW1G17C ~
$ ls !!:1:r
ls /bar/bar
ls: /bar/bar: No such file or directory

mw1g017@MW1G17C ~
$ ls  /bar/bar.baz/baz
ls: /bar/bar.baz/baz: No such file or directory

mw1g017@MW1G17C ~
$ ls !!:1:e
ls .baz/baz
ls: .baz/baz: No such file or directory

Hmm ... with :e modifier bash preserves dot and zsh not. csh here behaves as
zsh. Incidentally, csh here does treat strings like Alexander would like it:

itsrm2% !21
echo /bar/bar.baz/baz
/bar/bar.baz/baz
itsrm2% echo !!:1:r
echo /bar/bar.baz/baz
/bar/bar.baz/baz
itsrm2% echo !!:1:e
echo

-andrej