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Annotation of 43BSDTahoe/man/man2/getpriority.2, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1980 Regents of the University of California.
                      2: .\" All rights reserved.  The Berkeley software License Agreement
                      3: .\" specifies the terms and conditions for redistribution.
                      4: .\"
                      5: .\"    @(#)getpriority.2       6.5 (Berkeley) 5/22/86
                      6: .\"
                      7: .TH GETPRIORITY 2 "May 22, 1986"
                      8: .UC 4
                      9: .SH NAME
                     10: getpriority, setpriority \- get/set program scheduling priority
                     11: .SH SYNOPSIS
                     12: .nf
                     13: .ft B
                     14: #include <sys/resource.h>
                     15: .PP
                     16: .ft B
                     17: prio = getpriority(which, who)
                     18: int prio, which, who;
                     19: .PP
                     20: .ft B
                     21: setpriority(which, who, prio)
                     22: int which, who, prio;
                     23: .fi
                     24: .SH DESCRIPTION
                     25: The scheduling
                     26: priority of the process, process group, or user, as indicated by
                     27: .I which
                     28: and
                     29: .I who
                     30: is obtained with the
                     31: .I getpriority
                     32: call and set with the
                     33: .I setpriority
                     34: call.
                     35: .I Which
                     36: is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and 
                     37: .I who
                     38: is interpreted relative to 
                     39: .I which
                     40: (a process identifier for PRIO_PROCESS, process group
                     41: identifier for PRIO_PGRP, and a user ID for PRIO_USER).
                     42: A zero value of
                     43: .I who
                     44: denotes the current process, process group, or user.
                     45: .I Prio
                     46: is a value in the range \-20 to 20.  The default priority is 0;
                     47: lower priorities cause more favorable scheduling.
                     48: .PP
                     49: The
                     50: .I getpriority
                     51: call returns the highest priority (lowest numerical value)
                     52: enjoyed by any of the specified processes.  The
                     53: .I setpriority
                     54: call sets the priorities of all of the specified processes
                     55: to the specified value.  Only the super-user may lower priorities.
                     56: .SH "RETURN VALUE
                     57: Since
                     58: .I getpriority
                     59: can legitimately return the value \-1, it is necessary
                     60: to clear the external variable \fIerrno\fP prior to the
                     61: call, then check it afterward to determine
                     62: if a \-1 is an error or a legitimate value.
                     63: The
                     64: .I setpriority
                     65: call returns 0 if there is no error, or
                     66: \-1 if there is.
                     67: .SH ERRORS
                     68: .I Getpriority
                     69: and
                     70: .I setpriority
                     71: may return one of the following errors:
                     72: .TP 15
                     73: [ESRCH]
                     74: No process was located using the 
                     75: .I which
                     76: and
                     77: .I who
                     78: values specified.
                     79: .TP 15
                     80: [EINVAL]
                     81: .I Which
                     82: was not one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER.
                     83: .PP
                     84: In addition to the errors indicated above,
                     85: .I setpriority
                     86: may fail with one of the following errors returned:
                     87: .TP 15
                     88: [EPERM]
                     89: A process was located, but neither its effective nor real user
                     90: ID matched the effective user ID of the caller.
                     91: .TP 15
                     92: [EACCES]
                     93: A non super-user attempted to lower a process priority.
                     94: .SH "SEE ALSO"
                     95: nice(1), fork(2), renice(8)

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