getpriority(2)getpriority(2)NAME
getpriority, setpriority - Get or set process scheduling priority
SYNOPSIS
#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 get‐
priority() and setpriority() does not conform to current standards and
is supported only for backward compatibility:
int who
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
getpriority(), setpriority(): XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
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 identi‐
fier, 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 schedul‐
ing.
DESCRIPTION
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 set‐
priority() function sets the priorities of all of the specified pro‐
cesses 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.
RETURN VALUES
Upon successful completion, the getpriority() function returns an inte‐
ger 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 nec‐
essary 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.
ERRORS
The getpriority() and setpriority() functions set errno to the speci‐
fied 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.
SEE ALSO
Functions: exec(2), nice(3)
Standards: standards(5)getpriority(2)