Dash as default shell

Paolo Bonzini pbonzini at redhat.com
Mon Oct 6 06:06:07 UTC 2014


Il 02/10/2014 11:04, Zdenek Kabelac ha scritto:
> It used to give significant boost for automake & libtool based software
> - however at some point libtool started to use bashisms and so you
> cannot just replace  /bin/sh -> dash - as build will fail.

This is wrong.

libtool detects whether you can use bashisms, and falls back to POSIX
shell constructs if it cannot use them.  The non-POSIX constructs are
usually faster because they do not need to fork() the shell.  Autoconf
does the same.  dash rejects some of these constructs, and accept others.

Before Autoconf started doing this, dash was indeed quite a bit faster
than bash on configure scripts.  So your estimate of 50% is valid for
projects on which Autoconf has last been run 7-8 years ago.

Paolo


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