Re: POSIX shell; bash ash pdksh & /bin/sh

[Raul Miller <rdm@test.legislate.com>]

Manoj Srivastava <srivasta@datasync.com> wrote:
>  This discussion is mostly moot, since bash is an essential package,
>  and essential packages do not just go away on a whim. There are too
>  many scripts that depend on bash (calling /bin/bash explicitly); and
>  we have mentioned here in the past, essentially promising authors
>  that /bin/bash shall always exist).

There's also a performance issue.  On a heavily loaded system, /bin/sh
is likely to be run a number of times a second.  And, bash uses about
*four* *times* the system calls as ash:

$ strace sh -c : 2>&1 | wc -l
    125
$ strace ash -c : 2>&1 | wc -l
     31
$ 

As far as I know, none of the differences between ash and the posix
shell require all those extra system calls.

[Using "time", it looks like ash runs about three times faster than
bash, at least for trivial work.]

-- 
Raul


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