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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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NICE(3P) POSIX Programmer's Manual NICE(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
nice — change the nice value of a process
#include <unistd.h>
int nice(int incr);
The nice() function shall add the value of incr to the nice value
of the calling process. A nice value of a process is a non-
negative number for which a more positive value shall result in
less favorable scheduling.
A maximum nice value of 2*{NZERO}-1 and a minimum nice value of 0
shall be imposed by the system. Requests for values above or below
these limits shall result in the nice value being set to the
corresponding limit. Only a process with appropriate privileges
can lower the nice value.
Calling the nice() function has no effect on the priority of
processes or threads with policy SCHED_FIFO or SCHED_RR. The
effect on processes or threads with other scheduling policies is
implementation-defined.
The nice value set with nice() shall be applied to the process. If
the process is multi-threaded, the nice value shall affect all
system scope threads in the process.
As -1 is a permissible return value in a successful situation, an
application wishing to check for error situations should set errno
to 0, then call nice(), and if it returns -1, check to see whether
errno is non-zero.
Upon successful completion, nice() shall return the new nice value
-{NZERO}. Otherwise, -1 shall be returned, the nice value of the
process shall not be changed, and errno shall be set to indicate
the error.
The nice() function shall fail if:
EPERM The incr argument is negative and the calling process does
not have appropriate privileges.
The following sections are informative.
Changing the Nice Value
The following example adds the value of the incr argument, -20, to
the nice value of the calling process.
#include <unistd.h>
...
int incr = -20;
int ret;
ret = nice(incr);
None.
None.
None.
exec(1p), getpriority(3p)
The Base Definitions volume of POSIX.1‐2017, limits.h(0p),
unistd.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 NICE(3P)
Pages that refer to this page: unistd.h(0p), nice(1p), exec(3p), getpriority(3p)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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