getpriority(2)
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getpriority System Call
Get process scheduling priority.
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SYNTAX
#include <sys/resource.h>
int getpriority (which, who)
int which;
int who;
PARAMETERS
which Specifies how the argument <who> is to be
interpreted in identifying one or more processes
to get the priority for. It may take on the value
PRIO_PROCESS, PRIO_PGRP, or PRIO_USER.
who Identifies one or more processes to get the
priority for; may be a process ID, a process group
ID, or user ID, depending on the value of <which>.
DESCRIPTION
One or more processes are identified by the combination of the
arguments <which> and <who>. If <which> is PRIO_PROCESS, <who>
is interpreted as a process ID and a single process identified.
If <which> is PRIO_PGRP, <who> is interpreted as a process group
ID, and all processes that are members of that group are
identified. If <which> is PRIO_USER, <who> is interpreted as a
user ID, and all processes with effective-user-id of <who> are
identified. A <who> value of 0 is interpreted as the calling
process's process ID, process group ID, and effective-user-id,
respectively, for the three cases listed. For example, all
processes in the calling process' process group may be identified
with <which> set to PRIO_PGRP and <who> set to zero.
The getpriority call returns the highest priority (lowest
numerical value) enjoyed by any of the identified processes.
ACCESS CONTROL
No access checking is performed.
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getpriority(2)
RETURN VALUE
If no errors occur, getpriority returns the highest priority
(lowest numerical value) enjoyed by any of the identified
processes. If an error occurs, -1 is returned and errno is set
to identify the error.
Since 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 a -1 is an error or a
legitimate value.
EXCEPTIONS
Errno may be set to one of the following error codes:
ESRCH No process(es) were located using the <which> and
<who> values specified.
EINVAL <Which> was not one of PRIO_PROCESS, PRIO_PGRP, or
PRIO_USER.
SEE ALSO
The related system call: nice, fork.
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