system(4)							   File Formats 							 system(4)

NAME

       system - system configuration information file

DESCRIPTION

       The system file is used for customizing the operation of the operating system kernel. The recommended procedure is to preserve the original
       system file before modifying it.

       The system file contains commands which are read by the kernel during initialization and used to customize the operation  of  your  system.
       These commands are useful for modifying the system's treatment of its loadable kernel modules.

       The syntax of the system file consists of a list of keyword/value pairs which are recognized by the system as valid commands. Comment lines
       must begin with an asterisk (*) or a hash mark (#) and end with a newline character. All commands are case-insensitive except where noted.

       Commands that modify the system's operation with respect to loadable kernel modules require you to specify the module type by  listing  the
       module's namespace. The following namespaces are currently supported on all platforms:

       drv	 Modules in this namespace are device drivers.

       exec	 Modules in this namespace are execution format modules. The following exec modules are currently provided:

		 Only on SPARC system:
					       aoutexec

		 Only on x86 system:
					       coffexec

		 On SPARC and IA systems:
					       elfexec
					       intpexec
					       javaexec

       fs	 These modules are filesystems.

       sched	 These modules implement a process scheduling algorithm.

       strmod	 These modules are STREAMS modules.

       sys	 These modules implement loadable system-call modules.

       misc	 These modules do not fit into any of the above categories, so are considered "miscellaneous" modules.

       SPARC only:

       dacf    These modules provide rules and actions for device auto-configuration.

       tod     These modules provide support for the time of day hardware.

       cpu     These modules provide CPU-specific kernel routines.

       A description of each of the supported commands follows:

       exclude: <namespace>/<modulename>

	   Do not allow the listed loadable kernel module to be loaded. exclude commands are cumulative; the list of modules to exclude is created
	   by combining every exclude entry in the system file.

       include: <namespace>/<modulename>

	   Include the listed loadable kernel module. This is the system's default, so using include  does  not  modify  the  system's	operation.
	   include commands are cumulative.

       forceload: <namespace>/<modulename>

	   Force  this kernel module to be loaded during kernel initialization. The default action is to automatically load the kernel module when
	   its services are first accessed. forceload commands are cumulative.

       rootdev: <device name>

	   Set the root device to the listed value instead of using the default root device as supplied by the boot program.

       rootfs: <root filesystem type>

	   Set the root filesystem type to the listed value.

       moddir: <first module path>[[{:, }<second ...>]...]

	   Set the search path for loadable kernel modules. This command operates very much like the PATH shell variable. Multiple directories	to
	   search can be listed together, delimited either by blank spaces or colons.

       set [<module>:]<symbol> {=, |, &} [~][-]<value>

	   Set	an integer or character pointer in the kernel or in the selected kernel module to a new value. This command is used to change ker-
	   nel and module parameters and thus modify the operation of your system. Assignment operations are not cumulative, whereas  bitwise  AND
	   and OR operations are cumulative.

	   Operations  that are supported for modifying integer variables are: simple assignment, inclusive bitwise OR, bitwise AND, one's comple-
	   ment, and negation. Variables in a specific loadable module can be targeted for modification by specifying the variable  name  prefixed
	   with the kernel module name and a colon (:) separator. Values can be specified as hexadecimal(0x10), Octal(046), or Decimal(5).

	   The	only operation supported for modifying character pointers is simple assignment. Static string data such as character arrays cannot
	   be modified using the set command. Use care and ensure that the variable you are modifying is in fact a character pointer. The set com-
	   mand  is  very  powerful,  and  will  likely cause problems if used carelessly. The following escape sequences are supported within the
	   quoted string:

	     
   (newline)
	     	   (tab)
	        (backspace)

EXAMPLES

       Example 1 A sample system file.

       The following is a sample system file.

	 * Force the ELF exec kernel module to be loaded during kernel
	 * initialization. Execution type modules are in the exec namespace.
	 forceload: exec/elfexec
	 * Change the root device to /sbus@1,f8000000/esp@0,800000/sd@3,0:a.
	 * You can derive root device names from /devices.
	 * Root device names must be the fully expanded Open Boot Prom
	 * device name. This command is platform and configuration specific.
	 * This example uses the first partition (a) of the SCSI disk at
	 * SCSI target 3 on the esp host adapter in slot 0 (on board)
	 * of the SBus of the machine.
	 * Adapter unit-address 3,0 at sbus unit-address 0,800000.
	 rootdev: /sbus@1,f8000000/esp@0,800000/sd@3,0:a
	 * Set the filesystem type of the root to ufs. Note that
	 * the equal sign can be used instead of the colon.
	 rootfs:ufs
	 * Set the search path for kernel modules to look first in
	 * /usr/phil/mod_test for modules, then in /kernel/modules (the
	 * default) if not found. Useful for testing new modules.
	 * Note that you can delimit your module pathnames using
	 * colons instead of spaces: moddir:/newmodules:/kernel/modules
	 moddir:/usr/phil/mod_test /kernel/modules.
	 * Set the configuration option {_POSIX_CHOWN_RESTRICTED} :
	 * This configuration option is enabled by default.
	 set rstchown = 1
	 * Disable the configuration option {_POSIX_CHOWN_RESTRICTED} :
	 set rstchown = 0
	 * Turn on debugging messages in the modules mydriver. This is useful
	 * during driver development.
	 set mydriver:debug = 1
	 * Bitwise AND the kernel variable "moddebug" with the
	 * one's complement of the hex value 0x880, and set
	 * "moddebug" to this new value.
	 set moddebug & ~0x880
	 * Demonstrate the cumulative effect of the SET
	 * bitwise AND/OR operations by further modifying "moddebug"
	 * by ORing it with 0x40.
	 set moddebug | 0x40

SEE ALSO

       boot(1M), init(1M), kernel(1M)

WARNINGS

       Use care when modifying the system file; it modifies the operation of the kernel. If you preserved the original system file, you  can  boot
       using  boot  -a,  which	will  ask you to specify the path to the saved file. This should allow the system to boot correctly. If you cannot
       locate a system file that will work, you may specify /dev/null. This acts as an empty system file, and the  system  will  attempt  to  boot
       using its default settings.

NOTES

       The /etc/system file is read only once, at boot time.

SunOS 5.11							    3 Nov 2004								 system(4)