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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  new-
       line 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 follow-
           ing 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-configura-
           tion.



       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 oper-
           ates  very  much like the PATH shell variable. Multiple directories
           to search can be listed together, delimited either by blank  spaces
           or colons.



       set [&lt;module&gt;:]&lt;symbol&gt; {=, |, &} [~][-]&lt;value&gt;

           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  kernel  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 can-
           not be modified using the set command. Use care and ensure that the
           variable  you are modifying is in fact a character pointer. The set
           command is very powerful, and will likely cause  problems  if  used
           carelessly. The following escape sequences are supported within the
           quoted string:


           \n   (newline)
           \t   (tab)
           \b   (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 5.10                        3 Nov 2004                         system(4)