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
The above listing is from a Debian-server, your listing may look different.
Now, to execute a script before a reboot, just make sure it's listed here.
You should carefully pick the order in which you execute YOUR script, you don't want to stop your mailserver if you want your script to mail you something. I think you should be safe if you let the symlink to your script start with S10, so it gets executed almost at once.
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"
Then if I give it correct premission i.e. chmod a+rwx S10test. Then can I do shutdown now -r and I should see it been executed. Is this correct??
Thanks very much. I'll be unix guru at this rate (LOL) ...
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.
indo1144, I suggest you test it.
Create only a S10test (as alpha_manic was doing) in /etc/rc6.d as a link to /etc/init.d. Put in a sleep statement so you don't miss the message. See if it shows up during a shutdown now -r and if it's after the system has completed the shutdown and has restarted or before.
While the server is changing run levels (shutting down) it runs the K scripts, killing off processes - if it also ran the S scripts (to start processes), then you would have processes still running when the server was attempting to reboot.
indo1144,
I looked again at the output you posted for your /etc/rc6.d - very interesting. No wonder you state it will run (and probably will on Debian).
Here's Fedora's /etc/rc6.d listing
rc6.d]# ls
K01yum K20nfs K65krb524 K87portmap
K02cups-config-daemon K20tomcat5 K65krb5kdc K88syslog
K02haldaemon K24irda K66mDNSResponder K89named
K02NetworkManager K25squid K67nifd K89netplugd
K02NetworkManagerDispatcher K25sshd K68rpcidmapd K89rdisc
K03messagebus K30sendmail K69rpcgssd K90bluetooth
K03rhnsd K30spamassassin K69rpcsvcgssd K90network
K05anacron K35smb K72autofs K91isdn
K05atd K35vncserver K73ypbind K92iptables
K05saslauthd K35winbind K74apmd K94diskdump
K10cups K36mysqld K74nscd K95kudzu
K10dc_server K50netdump K74ntpd K96pcmcia
K10psacct K50tux K75netfs K99cpuspeed
K10xfs K56acpid K85mdmonitor S00killall
K12dc_client K60crond K85mdmpd S01reboot
K15gpm K65kadmin K86nfslock S10test
K15httpd K65kprop K87auditd
Note, that there are normally only two S scripts - killall and reboot - it would never get to S10test since the reboot script does a halt. Solaris doesn't have a /etc/rc6.d - it runs through the levels and runs all the K scripts and then reboots. So your information is correct for Debian - it may not be correct for any other UNIX OS.
I be~ieve that using K and S for starting and stopping daemon processes is standard for all Sys-V based OSes. In my experience with Solaris, and all Linuxes except Slackware, that's how it works. If you want to put a script before the reboot, you can just rename S01reboot to S02reboot and then make a new S01myscript. Unless you're sourcing /etc/init.d/functions in your script, you could even call it K??myscript (where ?? is an unused location) and it will just run the script at its turn. The S and K magic only happens if you include the init.d/functions file.