How to Write Suse Init Scripts

• System V Init – the style of init that both of my target OS’ use, or are compatible with (RHEL and Ubuntu).
  • Runlevels
  • /etc/rc.d
  • chkconfig (man page), and more detail in an old article
• The Linux Standards Base (LSB), and specifically, its standards for init scripts

Essentially, here’s what we need to do:

1. We put an executable script into /etc/init.d
2. We follow the LSB standard to ensure:
   1. the script works with LSB-compliant distros.
   2. dependant services are started/shutdown in the proper order.
3. use chkconfig to register the service.

This will create symlinks to our script in /etc/rc.d/rcX.d (where X is each runlevel we specified). One will be prefixed with an S, indicating a startup script, and another will be prefixed with K, for the kill or shutdown script.

The links will also be prefixed with numbers so that they can be sorted by the init system. This ensures they will start or shutdown in the proper order.

Script Requirements

Because of common convention, LSB standards, and the nuance of the chkconfig command, any init script we write will have to meet the following requirements:

1. It must be executable on the command-line.
2. It must support the following command-line options (actions):
   • start – start the service, called during boot
   • stop – stop the service, called during shutdown
   • restart – stop and then start the service; start it if it’s not running.
   • force-reload – reload configuration, but only if that is supported, otherwise, restart the service if it’s running
   • status – print the status of the service

   And optionally support the following actions:

   • reload – reload configuration information
   • try-restart – restart the service *only* if it’s already running
3. It must be placed into /etc/init.d. 
4. It must contain 2 comments indicating the requested start/shutdown order and the description (these are specified by the chkconfig man page):

            # chkconfig: 345 20 70
            # description: My service that rocks \
            # socks
            

   There must be a space between the hash mark and the chkconfig/description field name.

   The chkconfig: field indicates 3 space-separated values:

   1. what runlevels you want the service to run at (no spaces; a single dash means “don’t start by default in any runlevels”)
   2. What order you’d like the service to start
   3. What order you’d like the service to shut down

   Note the orders are just requests, the LSB block (defined below) and other dependencies will dictate the final start/shutdown order.

   The description: field describes what the service is. It can span multiple lines if you add a backslash before the carriage return, as illustrated above.

5. It must contain an LSB info block, with at least the Description, and Provides fields.
    

    

            ### BEGIN INIT INFO
            # Provides: myservice
            # Description: A service of mine that rocks socks 
            ### END INIT INFO
            

   The Description serves the same purpose as the chkconfig description (and they can be the same text).

   The Provides field lists all of the “boot facilities” that this service provides. This is used to set dependencies.

   Listing more than one can be useful if you are controlling multiple services, or replacing the standard init scripts (so you can specify cluster ocfs2 drbd, and any other drbd or ocfs2-dependant services will not need to be altered).

   However, it’s most likely you’ll want to also add the Required-Start and Required-Stop fields as well. These fields list “boot facilities” that your service requires during startup and shutdown.

            ### BEGIN INIT INFO
            # Provides: myservice
            # Description: A service of mine that rocks socks
            # Required-Start: nfs ntpd
            # Required-Stop: nfs
            ### END INIT INFO
            

   In this example, we’re telling chkconfig that our service mustn’t start before nfs and ntpd have started.

   There are also some “facilities” that are in-specific, and prefixed with a dollar sign. These include $network and $local_fs,
   which represent “the network is up” and “all local file systems are mounted”, respectively.

6. The script must write a file with the same name as the service to /var/lock/subsys.

   I’m having trouble finding concrete explanation as to why this is a requirement. All I’ve been able to find is a Red Hat “tips and tricks” entry (scroll down).

   So I’m not sure if this is a hard requirement, a Red Hat requirement, or what, but it was part of Coraid’s init script shell, and I don’t see any harm, so I’ve included it here.

Some other things to keep in mind:

• Best practice dictates that we put functions and such in external modules. This is difficult in the service/init script environment. The best thing to do is create an egg of your special dependancies and install it into your system python.

  There is a potential for putting the init script into an egg itself. I haven’t explored this yet, but it would allow for easy inclusion of local libraries, allow you to keep the init script simple, segregate tests from the script itself, and automatically install any external resources.

• Root will be executing this script, so be careful!
• This script is intended to control a separate application. It’s not an application in itself.

  The script is expected to exit after spawning the controlled application and return a relevant status code.

• Unit testing can be problematic. I’ve come up with a relatively cleaver way of dealing with that, which I will describe below.

Code Skeleton

The LSB specs call for a “library” of sorts that contains useful functions that help simplify init script creation. Most Linux distributions (or, at least the ones I’m dealing with here) include a variant, installed at /etc/init.d/functions.

At some point I’d like to emulate that entire library in python (or see if someone else already has), but there’s one bit in there that I really like, which would make these python-based init scripts look much more authentic.

When you send a command via /sbin/service servicename, or call the script using /etc/init.d/servicename, most distributions print a little colorized [ OK ] once a task has completed successfully (or [FAILED] upon failure). I think its worth the trouble to emulate that idea.

This is accomplished with a couple of new functions, named after shell functions I found in /etc/init.d/functions (on a RHEL5 machine).

Recommended Links

Softpanorama Recommended

Top articles

Sites

openSUSEPackaging init scripts - openSUSE

Creating a LSB standard Startup - Boot - Init Script under Ubuntu — RobPickering.com

Purely Python: LSB-Compliant Init Scripts

LSBInitScripts-DependencyBasedBoot - Debian Wiki

Unofficial SUSEFAQ - Starting and Stoping Services insserv

2.202.1 - Customising system startup and boot processes

SuSE Linux Guide for Geeks

Etc

Society

Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers :   Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism  : The Iron Law of Oligarchy : Libertarian Philosophy

Quotes

War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda  : SE quotes : Language Design and Programming Quotes : Random IT-related quotes :  Somerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce :  Bernard Shaw : Mark Twain Quotes

Bulletin:

Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 :  Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method  : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law

History:

Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds  : Larry Wall  : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOS :  Programming Languages History : PL/1 : Simula 67 : C : History of GCC development :  Scripting Languages : Perl history   : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history

Classic books:

The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month :  How to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Hater’s Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite

Most popular humor pages:

Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor

The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D

The statements, views and opinions presented on this web page are those of the author (or referenced source) and are not endorsed by, nor do they necessarily reflect, the opinions of the Softpanorama society. We do not warrant the correctness of the information provided or its fitness for any purpose. The site uses AdSense so you need to be aware of Google privacy policy. You you do not want to be tracked by Google please disable Javascript for this site. This site is perfectly usable without Javascript.

Last modified: March 12, 2019