NICE
Section: Linux Programmer's Manual (2)
Updated: 2007-07-26
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NAME
nice - change process priority
SYNOPSIS
#include <unistd.h>
int nice(int inc);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
nice():
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE
DESCRIPTION
nice()
adds
inc
to the nice value for the calling process.
(A higher nice value means a low priority.)
Only the superuser may specify a negative increment,
or priority increase.
The range for nice values is described in
getpriority(2).
RETURN VALUE
On success, the new nice value is returned (but see NOTES below).
On error, -1 is returned, and
errno
is set appropriately.
ERRORS
- 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).)
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001.
However, the Linux and (g)libc
(earlier than glibc 2.2.4) return value is nonstandard, see below.
SVr4 documents an additional
EINVAL
error code.
NOTES
SUSv2 and POSIX.1-2001 specify that
nice()
should return the new nice value.
However, the Linux syscall and the
nice()
library function provided in older versions of (g)libc
(earlier than glibc 2.2.4) return 0 on success.
The new nice value can be found using
getpriority(2).
Since glibc 2.2.4,
nice()
is implemented as a library function that calls
getpriority(2)
to obtain the new nice value to be returned to the caller.
With this implementation,
a successful call can legitimately return -1.
To reliably detect an error, set
errno
to 0 before the call, and check its value when
nice()
returns -1.
SEE ALSO
nice(1),
fork(2),
getpriority(2),
setpriority(2),
capabilities(7),
renice(1)
COLOPHON
This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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