SYSTEM(4)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
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-config‐
uration.
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 [<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 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 ALSOboot(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.
Nov 3, 2004 SYSTEM(4)
