Kao sto rece Dinko, osnovna uloga je automatizacija vise naredbi/akcija. Uzmi npr. neku obicnu init skriptu, recimo networking.
[code]#!/bin/sh -e
BEGIN INIT INFO
Provides: networking
Required-Start: mountkernfs $local_fs
Required-Stop: $local_fs
Should-Start: ifupdown
Should-Stop: ifupdown
Default-Start: S
Default-Stop: 0 6
Short-Description: Raise network interfaces.
END INIT INFO
PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"
[ -x /sbin/ifup ] || exit 0
. /lib/lsb/init-functions
process_options() {
[ -e /etc/network/options ] || return 0
log_warning_msg “/etc/network/options still exists and it will be IGNORED! Read README.Debian of netbase.”
}
check_network_file_systems() {
[ -e /proc/mounts ] || return 0
if [ -e /etc/iscsi/iscsi.initramfs ]; then
log_warning_msg "not deconfiguring network interfaces: iSCSI root is mounted."
exit 0
fi
exec 9<&0 < /proc/mounts
while read DEV MTPT FSTYPE REST; do
case $DEV in
/dev/nbd*|/dev/nd[a-z]*|/dev/etherd/e*)
log_warning_msg "not deconfiguring network interfaces: network devices still mounted."
exit 0
;;
esac
case $FSTYPE in
nfs|nfs4|smbfs|ncp|ncpfs|cifs|coda|ocfs2|gfs|pvfs|pvfs2|fuse.httpfs|fuse.curlftpfs)
log_warning_msg "not deconfiguring network interfaces: network file systems still mounted."
exit 0
;;
esac
done
exec 0<&9 9<&-
}
check_network_swap() {
[ -e /proc/swaps ] || return 0
exec 9<&0 < /proc/swaps
while read DEV MTPT FSTYPE REST; do
case $DEV in
/dev/nbd*|/dev/nd[a-z]*|/dev/etherd/e*)
log_warning_msg "not deconfiguring network interfaces: network swap still mounted."
exit 0
;;
esac
done
exec 0<&9 9<&-
}
case “$1” in
start)
process_options
log_action_begin_msg "Configuring network interfaces"
if ifup -a; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
;;
stop)
check_network_file_systems
check_network_swap
log_action_begin_msg "Deconfiguring network interfaces"
if ifdown -a --exclude=lo; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
;;
force-reload|restart)
process_options
log_warning_msg "Running $0 $1 is deprecated because it may not enable again some interfaces"
log_action_begin_msg "Reconfiguring network interfaces"
ifdown -a --exclude=lo || true
if ifup -a --exclude=lo; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
;;
*)
echo "Usage: /etc/init.d/networking {start|stop}"
exit 1
;;
esac
exit 0[/code]
Eh sada, da bi omogucio networking na linux masini dovoljno je da ovu skriptu pokrenes sa /etc/init.d/networking start.
U skripti su definisane varijable, funkcije, akcije.
Teoretski, networking mozes pokrenuti i bez ove skripte, ali u tom slucaju moras is shella rucno definisati sve varijable, sve funkcije, akcije… Zamisli koliko bi ti vremena trebalo da to uradis. Plus, jednom kad resetujes racunar, moras sve iz pocetka.
Bash ti omogucava da automatizira ovaj proces.
