topic Re: about scripts in /etc/rc.d in Operating System - Linux

about scripts in /etc/rc.d

Deepa_4 — Wed, 24 Mar 2004 06:08:21 GMT

Hi,

I like to know what is the significance of numbers in front of the softlinks in /etc/rc.d/rc3.d or rc6.d or...

The S indicates 'start' and K indicates 'kill'.
But what for the number?

For example I have seen S85httpd in rc3.d dir.
The number 85 stands for what?

Please brief

thanks in advance

Re: about scripts in /etc/rc.d

Alexander Chuzhoy — Wed, 24 Mar 2004 06:35:14 GMT

S85something will start before S86something
and that's the whole trick.

Re: about scripts in /etc/rc.d

Mark Grant — Wed, 24 Mar 2004 06:45:43 GMT

Yep, they don't have to be numbers. At least on your average Linux box they don't. Some systems don't even run them numerically but alphabetically which can get things in the worng order at times. If you want to see exactly what happens, have a look at /etc/rc. This is the "real" unix start up script but nowadays, generally runs things in the rc.* directories.

Re: about scripts in /etc/rc.d

Karthik S S — Wed, 24 Mar 2004 06:56:26 GMT

http://docs.sun.com/db/doc/805-7228/6j6q7uepi?a=view

They have explained everything neatly in the above link .. (who cares if it is a SUN site as long as the information provided applies to HP-UX aswell .. well it applies more or less)

-Karthik S S

Re: about scripts in /etc/rc.d

Deepa_4 — Wed, 24 Mar 2004 06:57:57 GMT

What exactly i want to know is:

I will be writing a script that should be called when reboot is given. So i will have a soft link to my script in /etc/rc.d/rc6.d directory.

I have seen all the file are having some numbers. see below:

K05news -> ../init.d/news
K08iBCS -> ../init.d/iBCS
K09samba -> ../init.d/samba
K12squid -> ../init.d/squid
K25gpm -> ../init.d/gpm
K25httpd -> ../init.d/httpd
K55snmpd -> ../init.d/snmpd
S99reboot -> ../init.d/reboot

I will be giving name of my script link which will start with 'S' . But what number I have to assign?

Is there any order these scripts should be called based on the numbers?

thank you

Re: about scripts in /etc/rc.d

Karthik S S — Wed, 24 Mar 2004 07:10:10 GMT

Deepa,

If you want a script to be invoked upon reboot then you must name it starting with the character 'K' and place it in /etc/rc.d/rc6.d directory. You can give it any number but unique one.

ex:
K77your_script

-Karthik S S

Re: about scripts in /etc/rc.d

Jean-Luc Oudart — Wed, 24 Mar 2004 08:29:18 GMT

init level 1,2,3 ...
if you have Snnxxx in rc2.d you will/should have Kmmxxx in rc1.d

The rule is mm + nn = 1000

The order is taken by this number , Therefore the last started daemons are killed first.

Jean-Luc

Re: about scripts in /etc/rc.d

Jeroen Peereboom — Wed, 24 Mar 2004 10:01:45 GMT

L.S.

As already said by other, the numbers determine the executing sequence of the scripts in the rcn.d directory. The 'n' is the runlevel (RedHat: 3 multi user, 5: Graphical multiuser). See /etc/inittab.

An easier way of maintaining all these softlinks is using chkconfig.
chkconfig -add service
chkconfig service on
chkconfig --list service

Check the manpage.
A commentline in your script may be needed. Check other scripts in /etc/init.d for an example.

JP.

Re: about scripts in /etc/rc.d

Martin P.J. Zinser — Wed, 24 Mar 2004 11:48:58 GMT

The thing you want to keep in mind is the prerequisits that your script needs. Lets say it still needs the network, so you have to select a number higher than used for the network start/stop script.

Greetings, Martin

Re: about scripts in /etc/rc.d

Olivier Drouin — Wed, 24 Mar 2004 15:59:39 GMT

And you can symlink your K01blah and S01blah to the same script.

The K01blah symlink will be called with "stop" argument and the S01blah will be called with "start" argument

Re: about scripts in /etc/rc.d

Stuart Browne — Wed, 24 Mar 2004 17:58:55 GMT

For the record, the number doesn't have to be unique.

Simply, /etc/rc.d/rc gets called by 'init', and does simple loops like:

for i in /etc/rc.d/rc6.d/K*
do
$i stop
done

(NOTE: On RH, it literally *IS* "for i in"!)

The numbers give the basic order of execution. All you really need to take into account is that your process is started after it's required subsystems are started, and stopped before it's required subsystems are stopped.

Usually this means you have a high S value (for rc 2/3/4/5), and a low K value (for rc 0/6).

As was said in the previous post, the values for S and K should add up to 100, but that isn't a 'rule', it's just a good guideline for keeping the start-up/shut-down orders equivalent.

Also note, that the order numbers are *ALWAYS* zero padded, i.e.:

S99MyRoutine
K01MyRoutine

To get an idea what order the start/stop will occur in, simply issue:

echo /etc/rc.d/rc3.d/S*

This will show the order they'll be executed in.

Re: about scripts in /etc/rc.d

Deepa_4 — Thu, 25 Mar 2004 04:08:00 GMT

thanks for all. So clear.

Deepa