1NICE(3P)                   POSIX Programmer's Manual                  NICE(3P)
2
3
4

PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10
11

NAME

13       nice — change the nice value of a process
14

SYNOPSIS

16       #include <unistd.h>
17
18       int nice(int incr);
19

DESCRIPTION

21       The nice() function shall add the value of incr to the  nice  value  of
22       the calling process. A nice value of a process is a non-negative number
23       for which a more positive value shall result in less favorable schedul‐
24       ing.
25
26       A maximum nice value of 2*{NZERO}−1 and a minimum nice value of 0 shall
27       be imposed by the system. Requests for values above or below these lim‐
28       its  shall  result  in  the  nice  value being set to the corresponding
29       limit. Only a process with appropriate privileges can  lower  the  nice
30       value.
31
32       Calling  the nice() function has no effect on the priority of processes
33       or threads with policy SCHED_FIFO or SCHED_RR.  The effect on processes
34       or threads with other scheduling policies is implementation-defined.
35
36       The  nice value set with nice() shall be applied to the process. If the
37       process is multi-threaded, the nice value shall affect all system scope
38       threads in the process.
39
40       As  −1  is  a  permissible  return  value in a successful situation, an
41       application wishing to check for error situations should set  errno  to
42       0,  then  call nice(), and if it returns −1, check to see whether errno
43       is non-zero.
44

RETURN VALUE

46       Upon successful completion, nice() shall  return  the  new  nice  value
47       −{NZERO}.   Otherwise,  −1  shall  be  returned,  the nice value of the
48       process shall not be changed, and errno shall be set  to  indicate  the
49       error.
50

ERRORS

52       The nice() function shall fail if:
53
54       EPERM  The  incr  argument is negative and the calling process does not
55              have appropriate privileges.
56
57       The following sections are informative.
58

EXAMPLES

60   Changing the Nice Value
61       The following example adds the value of the incr argument, −20, to  the
62       nice value of the calling process.
63
64           #include <unistd.h>
65           ...
66           int incr = -20;
67           int ret;
68
69           ret = nice(incr);
70

APPLICATION USAGE

72       None.
73

RATIONALE

75       None.
76

FUTURE DIRECTIONS

78       None.
79

SEE ALSO

81       exec, getpriority()
82
83       The Base Definitions volume of POSIX.1‐2008, <limits.h>, <unistd.h>
84

86       Portions  of  this text are reprinted and reproduced in electronic form
87       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
88       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
89       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
90       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
91       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
92       event of any discrepancy between this version and the original IEEE and
93       The Open Group Standard, the original IEEE and The Open Group  Standard
94       is  the  referee document. The original Standard can be obtained online
95       at http://www.unix.org/online.html .
96
97       Any typographical or formatting errors that appear  in  this  page  are
98       most likely to have been introduced during the conversion of the source
99       files to man page format. To report such errors,  see  https://www.ker‐
100       nel.org/doc/man-pages/reporting_bugs.html .
101
102
103
104IEEE/The Open Group                  2013                             NICE(3P)
Impressum