Customizing /etc/init.options

The file /etc/init and /usr/sbin/init are referred to synonymously as the initialization program that is run when the OMVS address space is initialized.

The /usr/sbin/init program invokes a shell to execute an initialization shell script that customizes the environment. When this shell script finishes or when a time interval established by /usr/sbin/init expires, kernel services become available for general batch and interactive use. Standard output (stdout) and standard error output (stderr) are redirected to /etc/log.

Table 1 lists the files that are associated with /usr/sbin/init.

Table 1. Files that are associated with /usr/sbin/init
File	What it is
/bin/sh	The default shell that /usr/sbin/init invokes to execute /etc/rc or another shell script that is specified in the /etc/init.options file.
/etc/init.options	The customized initialization options file, which is read by /usr/sbin/init.
/etc/rc	The default shell script that is used for initialization.
/etc/log	The file that output is written to.
Other utilities	Services that are called by the initialization shell script.

/usr/sbin/init and the customized /etc/init.options and /etc/rc are run at IPL. There is no other way to invoke them explicitly.

Before /usr/sbin/init invokes the shell to execute the system initialization shell script, it reads the file /etc/init.options for values of various options. The IBM-supplied default is in /samples/init.options. Copy this file to /etc/init.options and make the appropriate changes. If you already have /etc/init.options, then compare it to /samples/init.options and retrofit any new updates.

/usr/sbin/init treats all lines in /etc/init.options that do not start with a hyphen (-) as comment lines. Lines that start with a hyphen are used to specify options. The format of lines specifying options is as follows:

-oo  vvvvv comment

where:

oo is a field of one or more nonblank characters immediately following the hyphen that identifies the option. The end of the option field is delimited by one or more blanks.
vvvvv is a field of one or more nonblank characters that specify an option value. These characters are numeric, alphabetic, or a combination of both, depending on the option being specified. The end of the value field is delimited by one or more blanks.
Option and option value characters must appear in columns 1 through 79 of an option line in /etc/init.options. /usr/sbin/init ignores characters beyond column 79. However, a backslash (\) immediately following nonblank value field characters is recognized as a continuation character. If the continuation character is found, nonblank characters at the beginning of the next line are treated as option value characters. The first blank character delimits the end of the value field.

Option value characters on a continuation line are limited to columns 1 through 79.

The continuation character is recognized on continuation lines as well as the option line.
Any characters after a blank delimiting the end of the option value field on the same line are treated as comment characters.

Options and option value ranges are listed as follows:

-a nnnn

Alarm option. Specifies the maximum time in seconds allowed for the shell script to complete. You must specify enough time for the system initialization script to complete if this is a requirement at your installation.

The default is 180 seconds.

The maximum is 9999 seconds.

If the shell does not signal completion of the script before this time elapses, /usr/sbin/init writes the timeout error message, FSUM4013I, in /etc/log and exits.

If the value 0 is specified, no timeout interval is set. The decision to specify the value 0 for the alarm option should be made carefully and only after you know that the initialization script is error-free.

-t n

Terminate option. Specifies whether to end the shell script initialization if the timeout specified by the alarm option (-a) occurs.

0: Allows the shell script to continue
>0: Ends the shell script
1: The default; ends the shell script.

If you specify terminate and the timeout waiting for the initialization shell script occurs, /usr/sbin/init sends a stop signal to the shell process group.

It is your responsibility to decide if the initialization shell script can continue concurrently with batch and interactive use of the shell.

-e string

Environment variable option: string in the form name=value specifies the environment variable name and the value that /usr/sbin/init passes to the shell that it is invoking

The maximum length is 255 characters.

/etc/init.options can contain up to 25 -e option lines specifying names and values for different environment variables. /usr/sbin/init passes the resultant environment variable array to the shell that it invokes. In turn, the shell uses this array to set up an execution environment for the initialization shell script that is appropriate for the installation. TZ is an example of an environment variable that should be considered.

These environment variables should also be set up in /etc/profile or $HOME/.profile for each interactive user. Examples of variables that you could specify are TZ, LANG, and NLSPATH.

-sc pathname

The path name of the initialization shell script.

The default is /etc/rc.

The maximum length is 255 characters.

-sh pathname

pathname specifies the shell to be invoked by /usr/sbin/init to run the initialization script. /usr/sbin/init cannot set environment variables for the rest of the system.

The default is /bin/sh.

The maximum length is 255 characters.

-sh <blanks> tells /usr/sbin/init not to run the shell. Instead, /usr/sbin/init signals that multiuser mode is to be entered and then exits.

Following is a sample /etc/init.options file showing the time zone, the Japanese language, and the locale:

-e TZ=JST-9
-e LANG=Ja_JP
-e NLSPATH=/usr/lib/nls/msg/%L/%N

/etc/init opens the message catalog fsumucat.cat in directory /usr/lib/nls/msg/C unless an NLSPATH environment variable naming a different directory is specified in the /etc/init.options file.

For more information about national language support, see Customizing for your national code page in the shell.

Tip: You can use a REXX exec in an MVS™ data set as an alternative to running the /etc/init initialization program. To activate the REXX exec for initialization, you must specify its name on the STARTUP_EXEC statement in the BPXPRMxx parmlib member.