Re: RFC: Changing AC_DEFINE

[Alexandre Oliva]

On Jun  9, 2001, "Tim Van Holder" <address@hidden> wrote:

Alexandre> IMO, the best way to go is for autoconf to come up with a
Alexandre> safe echo, i.e., one that won't mess up any characters,
Alexandre> will preserve backslashes, etc, in a similar way that
Alexandre> libtool does.  In fact, this would help libtool a lot as we
Alexandre> move more of it into m4sh.

>> > Well, why not!

>> Err...  Because someone has to do it? :-)

> Well, an easy situation would be if the shell is bash; it's builtin echo
> has a -E option to do just that (i.e. not expand anything).  I had to
> use that option in a few changes I made for the DJGPP package, as
> autoconf would otherwise seriously mess up DOS-style paths.
> Not sure if other incarnations of echo are so friendly as to provide
> such a option though.

I'm afraid not even -E is a complete solution.  Try, for example:

echo -E -e '\a'

and note that `-e' isn't echoed, and you get a beep, not a literal
`\a'.

That's why libtool always uses:

  $echo "X$whatever" | $Xsed

where Xsed is:

  sed -e '1s/^X//'


But this is another problem of portable echoing.  It's amazing that
something as simple as plain echoing can't be done easily :-(

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  address@hidden, redhat.com}
CS PhD student at IC-Unicamp        address@hidden, gnu.org}
Free Software Evangelist    *Please* write to mailing lists, not to me