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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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nice(2) System Calls Manual nice(2)
nice - change process priority
Standard C library (libc, -lc)
#include <unistd.h>
int nice(int inc);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
nice():
_XOPEN_SOURCE
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
nice() adds inc to the nice value for the calling thread. (A
higher nice value means a lower priority.)
The range of the nice value is +19 (low priority) to -20 (high
priority). Attempts to set a nice value outside the range are
clamped to the range.
Traditionally, only a privileged process could lower the nice
value (i.e., set a higher priority). However, since Linux
2.6.12, an unprivileged process can decrease the nice value of a
target process that has a suitable RLIMIT_NICE soft limit; see
getrlimit(2) for details.
On success, the new nice value is returned (but see NOTES below).
On error, -1 is returned, and errno is set to indicate the error.
A successful call can legitimately return -1. To detect an
error, set errno to 0 before the call, and check whether it is
nonzero after nice() returns -1.
EPERM The calling process attempted to increase its priority by
supplying a negative inc but has insufficient privileges.
Under Linux, the CAP_SYS_NICE capability is required.
(But see the discussion of the RLIMIT_NICE resource limit
in setrlimit(2).)
C library/kernel differences
POSIX.1 specifies that nice() should return the new nice value.
However, the raw Linux system call returns 0 on success.
Likewise, the nice() wrapper function provided in glibc 2.2.3 and
earlier returns 0 on success.
Since glibc 2.2.4, the nice() wrapper function provided by glibc
provides conformance to POSIX.1 by calling getpriority(2) to
obtain the new nice value, which is then returned to the caller.
POSIX.1-2008.
POSIX.1-2001, SVr4, 4.3BSD.
For further details on the nice value, see sched(7).
Note: the addition of the "autogroup" feature in Linux 2.6.38
means that the nice value no longer has its traditional effect in
many circumstances. For details, see sched(7).
nice(1), renice(1), fork(2), getpriority(2), getrlimit(2),
setpriority(2), capabilities(7), sched(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 nice(2)
Pages that refer to this page: nice(1), getpriority(2), getrlimit(2), sched_setaffinity(2), sched_setattr(2), sched_setparam(2), sched_setscheduler(2), syscalls(2), capabilities(7), sched(7)
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HTML rendering created 2024-06-26 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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