Re: Replacing sed for zsh portability

[DervishD <zsh@dervishd.net>]

    Hi Vincent :)

 * Vincent Lefevre <vincent@vinc17.org> dixit:
> On 2005-08-16 17:51:14 +0200, DervishD wrote:
> >     The thing is perfectly suitable to be done in sed, in fact it is
> > a one-liner (three lines if non-GNU sed), and it can even be done in
> > one or two lines in Zsh. Introducing a dependency with Perl just for
> [...]
> The problem with sed is that it is non-portable, and it is difficult
> to be sure that a sed call will work as expected on any machine.

    I know, but both POSIX and SUS have standarized a (big) subset of
sed programs, and I would tell that 100% of the sed's out there
support the 's' command. In fact, a system without a working sed (I
mean, a sed that doesn't understand the 's' command) won't run
'configure' scripts properly and so is possible that zsh won't
compile on them, so...
 
> With zsh, things related to regexp are difficult to read, and the
> behaviour often depends on options (one needs to remember to use
> "emulate -LR zsh", and this should be OK, however).

    That's for sure, I will use 'emulate' because it ensures (more or
less) a sane default, known environment. And I don't care about
readability because Perl is not readable and the end user won't ever
see the regex, it's me who is going to maintain it ;)
 
> I've had to switch to Perl for a simple replacement just because
> in-place editing with sed isn't supported everywhere, and when it
> is supported, it doesn't behave in the same way on every machine.

    Well, in place editing is just a shortcut for doing a couple of
'mv's. The only problem can be side effects in the middle of the
moves, but if Perl does the in-place editing using a temporary file
and a rename... I don't know how it is done neither in Perl nor in
sed, anyway.

    Raúl Núñez de Arenas Coronado

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