getpriority, setpriority - Get or set process scheduling
priority
#include <sys/resource.h>
int getpriority(
int which,
id_t who ); int setpriority(
int which,
id_t who,
int priority) );
[Tru64 UNIX] The following declaration of the who parameter
for getpriority() and setpriority() does not conform
to current standards and is supported only for backward
compatibility:
int who
Interfaces documented on this reference page conform to
industry standards as follows:
getpriority(), setpriority(): XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Specifies one of PRIO_PROCESS (process priority),
PRIO_PGRP (process group priority), or PRIO_USER (user
priority). Specifies a numeric value interpreted relative
to the which parameter (a process identifier, process
group identifier, and a user ID, respectively). A 0
(zero) value for the who parameter denotes the current
process, process group, or user. Specifies a value in the
range -20 to 20. The default priority is 0 (zero); negative
priorities cause more favorable scheduling.
The getpriority() function obtains the current priority of
a process, process group, or user. The getpriority() function
returns the highest priority (lowest numerical value)
pertaining to any of the specified processes.
The setpriority() function sets the scheduling priority of
a process, process group, or user. If you specify more
than one process, the setpriority() function sets the priorities
of all of the specified processes to the specified
value. If the specified value is less than -20, a value
of -20 is used; if it is greater than 20, a value of 20 is
used.
Upon successful completion, the getpriority() function
returns an integer in the range -20 to 20. Otherwise, -1
is returned and errno is set to indicated the error.
Because getpriority() can legitimately return the value
-1, it is necessary to clear the external variable errno
prior to the call, then check it afterward to determine if
-1 is an error or a legitimate value.
Upon successful completion, the setpriority() function
returns 0 (zero). Otherwise, the function returns -1 and
sets errno to indicate the error.
The getpriority() and setpriority() functions set errno to
the specified values for the following conditions: No process
was located using the specified which and who parameter
values. The which parameter was not recognized.
In addition to the errors indicated above, the setpriority()
function can fail with errno set to one of the following
values: The process does not have ownership rights
with respect to the target process's real user ID. The
process is trying to raise its priority and does not have
the appropriate privilege.
Functions: exec(2), nice(3)
Standards: standards(5)
getpriority(2)
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