| Linux / Unix Command: setpriority |
NAME
getpriority, setpriority - get/set program scheduling prioritySYNOPSIS
#include <sys/time.h>#include <sys/resource.h>
int getpriority(int which, int who);
int setpriority(int which, int who, int prio);
DESCRIPTION
The scheduling priority of the process, process group, or user, as indicated by which and who is obtained with the getpriority call and set with the setpriority call. Which is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and who is interpreted relative to which (a process identifier for PRIO_PROCESS, process group identifier for PRIO_PGRP, and a user ID for PRIO_USER). A zero value for who denotes (respectively) the calling process, the process group of the calling process, or the real user ID of the calling process. Prio is a value in the range -20 to 20 (but see the Notes below). The default priority is 0; lower priorities cause more favorable scheduling.The getpriority call returns the highest priority (lowest numerical value) enjoyed by any of the specified processes. The setpriority call sets the priorities of all of the specified processes to the specified value. Only the super-user may lower priorities.
RETURN VALUE
Since getpriority can legitimately return the value -1, it is necessary to clear the external variable errno prior to the call, then check it afterwards to determine if a -1 is an error or a legitimate value. The setpriority call returns 0 if there is no error, or -1 if there is.ERRORS
- ESRCH
- No process was located using the which and who values specified.
- EINVAL
- Which was not one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER.
In addition to the errors indicated above, setpriority may fail if:
- EPERM
- A process was located, but neither the effective nor the real user ID of the caller matches its effective user ID.
- EACCES
- A non super-user attempted to lower a process priority.
SEE ALSO
nice(1), fork(2), renice(8)
Important: Use the man command (% man) to see how a command is used on your particular computer.
