Hi Guys,

I want to execute few of my bash script, so that whenever someone calls shutdown now -r command, I want my script to execute first before shutting down.

Any help please?????

I've just started playing with the unix system, so far its been brilliant....

When you reboot, what you actually do is change the runlevel to 6. In /etc/init.d you can find all kinds of scripts that are started/stopped when entering specific runlevels. This is where your script should live (or be symlinked to).

Now change into /etc/rc6.d. You see lots of symlinks to the scripts in /etc/init.d. Some start with a K, some start with an S. When changing to runlevel 6 (read: you execute a shutdown -r now), the services that start with a K will be stopped, the ones starting with an S will be started. (See where I'm going?)

The number after K or S is an indication of the order in which these scripts will be run.

root@k2:/etc/rc6.d# ls -l
total 0
lrwxrwxrwx  1 root root  18 Apr  4  2001 K10ipchains -> ../init.d/ipchains
lrwxrwxrwx  1 root root  14 Mar 26  2001 K11cron -> ../init.d/cron
lrwxrwxrwx  1 root root  17 Mar 26  2001 K12kerneld -> ../init.d/kerneld
lrwxrwxrwx  1 root root  16 Apr  4  2001 K20apache -> ../init.d/apache
lrwxrwxrwx  1 root root  15 Mar 26  2001 K20inetd -> ../init.d/inetd
lrwxrwxrwx  1 root root  17 Mar 26  2001 K20logoutd -> ../init.d/logoutd
lrwxrwxrwx  1 root root  17 Mar 26  2001 K20makedev -> ../init.d/makedev
lrwxrwxrwx  1 root root  17 Apr  4  2001 K20postfix -> ../init.d/postfix
lrwxrwxrwx  1 root root  16 Dec  9  2003 K20rinetd -> ../init.d/rinetd
lrwxrwxrwx  1 root root  15 May  9  2003 K20snmpd -> ../init.d/snmpd
lrwxrwxrwx  1 root root  13 Mar 29  2001 K20ssh -> ../init.d/ssh
lrwxrwxrwx  1 root root  19 Jan 26  2005 K20tivoli-sm -> ../init.d/tivoli-sm
lrwxrwxrwx  1 root tiggr 15 Apr 12  2001 K21resin -> ../init.d/resin
lrwxrwxrwx  1 root tiggr 13 Apr  9  2001 K23ntp -> ../init.d/ntp
lrwxrwxrwx  1 root root  20 Dec  6  2003 K25hwclock.sh -> ../init.d/hwclock.sh
lrwxrwxrwx  1 root tiggr 25 Jul 10  2002 K25nfs-user-server -> ../init.d/nfs-user-server
lrwxrwxrwx  1 root  1005 15 Oct 10  2003 K25resin -> ../init.d/resin
lrwxrwxrwx  1 root root  19 Mar 26  2001 K30setserial -> ../init.d/setserial
lrwxrwxrwx  1 root tiggr 17 May 23  2002 K50proftpd -> ../init.d/proftpd
lrwxrwxrwx  1 root tiggr 14 Apr 20  2003 K85bind -> ../init.d/bind
lrwxrwxrwx  1 root root  13 Mar 26  2001 K89atd -> ../init.d/atd
lrwxrwxrwx  1 root root  15 Apr  4  2001 K89klogd -> ../init.d/klogd
lrwxrwxrwx  1 root root  18 Mar 26  2001 K90sysklogd -> ../init.d/sysklogd
lrwxrwxrwx  1 root root  17 Mar 26  2001 S10portmap -> ../init.d/portmap
lrwxrwxrwx  1 root root  18 Mar 26  2001 S20sendsigs -> ../init.d/sendsigs
lrwxrwxrwx  1 root root  17 Mar 26  2001 S30urandom -> ../init.d/urandom
lrwxrwxrwx  1 root root  22 Mar 26  2001 S31umountnfs.sh -> ../init.d/umountnfs.sh
lrwxrwxrwx  1 root root  20 Mar 26  2001 S35networking -> ../init.d/networking
lrwxrwxrwx  1 root root  18 Mar 26  2001 S40umountfs -> ../init.d/umountfs
lrwxrwxrwx  1 root root  16 Mar 26  2001 S90reboot -> ../init.d/reboot

I have a brand new installation and only consist of S20reboot. So according to your article above, if i create a script called S10test which could contain something like :

#! /bin/sh
echo "hello unix world"

Scripts starting with S are executed on Startup. Scripts starting with K are executed on shutdown. So, no, your script will be seen on boot, not on shutdown.

It's my understanding that K scripts are Killed when you enter that runlevel, and S scripts are Started. So rc6.d/K10ssh will kill the ssh daemon when you enter runlevel 6, but rc6.d/S10foo will start the foo daemon.

All that depends on the init.d/foo or ssh scripts using the right functions to parse $0 correctly, of course. If you don't do that, I don't think it matters what you name the rc?.d script - it'll just run when you enter that runlevel.

Original request He wants something to run before shutting down - that means he wants a K script - that is why I stated the difference between S and K - he stated he wanted to see execution BEFORE shutting down - naming the script S10test, would cause him to see execution AFTER shutdown on reboot.

That's right, although the execution of your script may happen so fast, you won't see the output.
This can be quite confusing. Last week I had to dig into this matter, because I had to create my own init-script from scratch and I stumbled upon the following text.
So the S10test script will in fact be executed prior to the actual reboot.