The reason that normal startup scripts don't, is that there's no guarantee
/bin/sh will point to bash, or even that bash is installed.
If you want to use bash, the first line should be /bin/bash instead of
/bin/sh, so it's obvious it needs bash specifically.
Jon
On Sun, 28 Sep 2003, [iso-8859-1] Manoj Kumar wrote:
> Is there any reason not to use bash features in init
> scripts?
> Consider, for example, this fragment from
> /etc/sysconfig/network-scripts/ifup-post:
>
> DEVICETYPE=`echo $DEVICE | sed "s/[0-9]*$//"`
> REALDEVICE=`echo $DEVICE | sed 's/:.*//g'`
> if echo $DEVICE | grep -q ':' ; then
> ISALIAS=yes
> else
> ISALIAS=no
> fi
>
> In bash we can do this much faster with something like
> this:
>
> DEVICETYPE=$DEVICE
> while [[ $DEVICETYPE == *[0-9] ]]; do
> DEVICETYPE=${DEVICETYPE%[0-9]}
> done
> REALDEVICE=${DEVICE%%:*}
> if [[ $DEVICE == *:* ]]; then
> ISALIAS=yes
> else
> ISALIAS=no
> fi
>
> Okay, the loop that replaces the first line is messy,
> but it saves
> a couple of forks and an exec. The other two changes
> are both
> simpler and faster.
>
> So why do most init scripts use sed and grep to
> process
> strings? It can't be a desire to allow them to work
> with the
> Bourne shell (why would we want that anyway?) because
> some
> scripts do use bash features.
>
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>
>
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