Re: [PATCH] echo: fix octal escaping with \1...\7

[Mike Frysinger <vapier@gentoo.org>]

[-- Attachment #1: Type: Text/Plain, Size: 1975 bytes --]

On Sunday 30 October 2011 23:41:58 Herbert Xu wrote:
> Mike Frysinger wrote:
> > POSIX states that octal escape sequences should take the form \0num
> > when using echo.  dash however additionally treats \num as an octal
> > sequence.  This breaks some packages (like libtool) who attempt to
> > use strings with these escape sequences via variables to execute sed
> > (since sed ends up getting passed a byte instead of a literal \1).
> 
> OK this is a bit of problem.  From our conversation I had the
> impression that you were referring to the lack of support of
> escape codes, rather than unwanted support.
> 
> If it was the former I could easily add it if POSIX said so,
> however, as this is an existing feature there may well be scripts
> out there that depend on it.  So removing it is not an option
> unless it is explicitly forbidden by POSIX.

i'm not seeing how this jives with dash's goal.  if it intends to be a 
fast/small POSIX compliant shell while punting (almost) all the rest, then why 
carry additional functionality that POSIX doesn't even mention in passing ?  
this isn't "documented but optional extended functionality", but rather the 
realm of "anything goes".  otherwise we approach the same realm that dash was 
created to avoid -- carrying lots of cruft that slow things down because 
scripts use it rather than POSIX mandating it.

as a comparison, bash/ksh/tcsh/zsh/busybox[ash] all behave the way my patch 
updates dash to operate ... i would test more shells, but these tend to be the 
standards that everyone compares against.  i can't see people writing scripts 
that only work under dash either.

> In any case, scripts that rely on escape codes like this are
> simply broken and should either be fixed to use printf or just
> run with #!/bin/bash.

they're relying on these escape codes not being interpreted as escape codes 
(which every other shell appears to do), not the other way around
-mike

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 836 bytes --]