uadmin - administrative control
int uadmin(int cmd, int fcn, int mdep);
uadmin provides control for basic administrative functions. This system
call is tightly coupled to the system administrative procedures and is
not intended for general use. The argument mdep is provided for
machine-dependent use and is not defined here.
As specified by cmd, the following commands are available:
A_SHUTDOWN The system is shut down. All user processes are killed,
the buffer cache is flushed, and the root file system (and
no other) is unmounted. The action to be taken after the
system has been shut down is specified by fcn. The
functions are generic; the hardware capabilities vary on
AD_HALT Halt the system.
AD_BOOT Reboot the system.
AD_IBOOT Interactive reboot; the system goes to
firmware mode and the user is prompted for
bootable program name. Not supported; it is
treated the same as AD_HALT.
AD_POWEROFF Halt the processor and turn off the power with
A_REBOOT or A_SHUTDOWN. With A_SETFLAG,
simply sets the flag so that a subsequent
A_SHUTDOWN or A_REBOOT also powers off.
A_REBOOT The system stops immediately without any further
processing. The action to be taken next is specified by
fcn as above.
A_REMOUNT The root file system is mounted again after having been
fixed. This should be used only during the startup
A_KILLALL All processes are killed except those belonging to the
process group specified by fcn. They are sent the signal
specified by mdep.
A_SETFLAG Set a flag to control later actions. Currently
implemented only for AD_POWEROFF.
uadmin fails if any of the following are true:
EPERM The calling process does not have super-user privilege.
Upon successful completion, the value returned depends on cmd as follows:
A_SHUTDOWN Never returns.
A_REBOOT Never returns.
Otherwise, a value of -1 is returned and errno is set to indicate the
Require the following in the permitted capability set:
CAP_SHUTDOWN Privilege to shutdown or reboot the system.
syssgi(2), uadmin(1), capabilities(4).
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