Customizing your installation

You can customize your AIX® installation. Customizing an installation requires you to edit the file and use it with your installation media.

The first time you install, the Base Operating System (BOS) installation program presents menus from which you must choose setup options. This initial installation also automatically starts a post-installation configuration program, either the graphical Configuration Assistant or the ASCII Installation Assistant.

For subsequent installations, you can change many aspects of the default BOS install program by editing the file. For example, to install the BOS without menus, you can specify that no prompts be provided. You can also customize a BOS installation to bypass Configuration Assistant or Installation Assistant and start your own configuration script. Also, the file can be used to replicate one set of installation settings on other machines. Set the CONNECTION field for obtaining the correct hard disk information for each system. For example, system administrators can create a file with settings that can be used to install all the machines they support that have the same configuration.

If you run your own configuration script from a file or from the Network Installation Management (NIM) interface, the environment that is in place at the time the script is run is a single-user environment. This environment is not available as a multiuser environment, and thus, there are limits to what can be run from a configuration script. The /etc/init file is not running, so no process management can take place. All available memory cannot be made available because the RAM file system still exists, so devices that require large amounts of memory to run might fail to configure. In addition, signal handling is not available.

Because of the single-user environment, use the following guidelines for configuration scripts:
  • Base devices can be configured, but devices that require daemons or more complex configuration should be started at reboot time by adding the necessary code to the end of the /etc/firstboot script.
  • Daemons should not be started.
  • Items such as NIS configuration, which uses system resource controller (SRC) commands, should be done by creating a separate entry in the /etc/inittab file and running a configuration script at reboot time.
  • The BOS installation process automatically creates and extends paging space based on available memory.

The file directs the actions of the BOS installation program. The file resides in the /var/adm/ras directory on the installed machine only, and it is not accessible on the commercial tape or the media on which you received AIX.

The file contains stanzas with variables set to default values. Each variable is on a new line, in the Variable=Value form. A blank line separates each stanza. These stanzas provide the installation program with information such as the method and type of installation, the disks in the machine, and the language used. By editing the file with an ASCII text editor, you can substitute new values for the default variables.

Another installation file,, can also be modified and used during BOS installation. The file contains information describing the root volume group image created during the BOS installation process. This information includes the sizes, names, maps, and mount points of logical volumes and file systems in the root volume group. The installation program also takes input from the file regarding defaults for the machine being installed. The procedure for using the file to customize BOS installation can also be used for the file. The modified files can be used together to override BOS installation defaults.

You can also use the instructions in this chapter to create a supplemental diskette, a CD-R, or a DVD-RAM containing a modified preserve.list file, which is used during a preservation Installation.