CIT054 Index > Assignment - Startup Scripts

Assignment - Startup Scripts

The book’s discussion of startup scripts on pages 28-35 presumes that you will manually add symbolic links in the appropriate rclevel.d directories (see bottom of page 30).

This is, in fact, the method you have to use with Ubuntu, because, as the book says, the Debian scripts are “fragile, uncodumented, and outrageously inconsistent.” Becaused you are manually setting up links, you will have to keep track of the numbers following the K or S to make sure everything is in the right order.

Systems that conform to the Linux Standard Base have a better way of setting up startup scripts. In each startup script, you include a block of comments that give information to the init script. This block of comments (called “init info”) tells:

Here is the detailed specification of the init info format.

A third method, which is what some other distributions use, is to insert information that the chkconfig utility uses. Quoting from the man page:

Each service which should be manageable by chkconfig needs two or more commented lines added to its init.d script. The first line tells chkconfig what runlevels the service should be started in by default, as well as the start and stop priority levels. If the service should not, by default, be started in any runlevels, a - should be used in place of the runlevels list. The second line contains a description for the service, and may be extended across multiple lines with backslash continuation.

For example, random.init has these three lines:

       # chkconfig: 2345 20 80
       # description: Saves and restores system entropy pool for \
       #              higher quality random number generation.

This says that the random script should be started in levels 2, 3, 4, and 5, that its start priority should be 20, and that its stop priority should be 80. You should be able to figure out what the description says; the \ causes the line to be continued. The extra space in front of the line is ignored.

In this assignment, you will change this incomplete init script as follows:

  1. Save the script in a file whose name has the form lastname_firstInitial. Thus, if your name is John Smith, the script name would become smith_j
  2. Similarly, change the Provides information to match the new script name.
  3. Change the word cit054 in the line starting LOCKFILE to match the new script name; thus, for John Smith, the line would read LOCKFILE=/var/lock/subsys/smith_j
  4. In the init info, specify that the $syslog (system logging) and resolvconf services must be started before this script starts.
  5. Add chkconfig and init info information that tells the script to start in run level 2 only and stop in all other levels.
  6. In the chkconfig information, set the start priority of this script to 98, and its stop priority to 95
  7. Find the gprintf statements in the script and replace the words [[your full name here]] with your full name.

Differences in Ubuntu

Ubuntu does not have the insserv program on the standard install. Do not install and use it; if you do, it will ruin your life. Ubuntu is now using a system called upstart for initializing system services. When it is fully implemented, there will be no /etc/init.d directory. Instead, there will be scripts in the /etc/event.d directory that are called when certain events occur. As of Ubuntu 7.04, these scripts are set up to emulate the existing /etc/rcn.d structure. (You can see some documentation on script-writing, but it’s not easy reading.)

Ubuntu (and Debian) treat run levels 2-5 as identical. The default runlevel is 2, and it is not specified in /etc/inittab; in fact, the file doesn’t exist.

Testing Your Changes Locally

Do not upload this script to the CIT054 server and install the service right away! Instead, test it on your local Linux system. You will have to put the script into the /etc/init.d directory, and change its permissions to 0755. You’ll want to do the rest of the testing in a text-only console, which you may get to by pressing CTRL-ALT-F2. (You may return to graphic mode with CTRL-ALT-F7.)

If you are using Mandriva,use chkconfig by going to a shell prompt and typing 

cd /etc/init.d
chkconfig --add name_of_your_script

On Mandriva, the chkconfig program has been written to use the Linux Standard Base init info.

Then, from the command line, you can type init 2 and init 3 to see that your script is indeed being called at the appropriate times and places. After you switch runlevels, you may have to press ENTER to see the shell prompt. The script also places output into a file /tmp/initstuff so that you can see when the script started and stopped (in case the messages scroll past too fast for you to read them).

Finishing the Assignment

Upload your script to the server into your home directory. You can’t put the upload directly into /etc/init.d because you can’t FTP into the server as root. After you FTP, log in via secure shell, and use su or sudo to move the file into the proper directory, set its permissions, name it as you did on your own machine to install it. When you finish, email me to let me know you’ve finished.