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-rw-r--r-- | man2/nice.2 | 118 |
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diff --git a/man2/nice.2 b/man2/nice.2 new file mode 100644 index 0000000..d26a1be --- /dev/null +++ b/man2/nice.2 @@ -0,0 +1,118 @@ +.\" Copyright (c) 1992 Drew Eckhardt <drew@cs.colorado.edu>, March 28, 1992 +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" Modified by Michael Haardt <michael@moria.de> +.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu> +.\" Modified 1996-11-04 by Eric S. Raymond <esr@thyrsus.com> +.\" Modified 2001-06-04 by aeb +.\" Modified 2004-05-27 by Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.TH nice 2 2023-03-30 "Linux man-pages 6.05.01" +.SH NAME +nice \- change process priority +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <unistd.h> +.PP +.BI "int nice(int " inc ); +.fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.BR nice (): +.nf + _XOPEN_SOURCE + || /* Since glibc 2.19: */ _DEFAULT_SOURCE + || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE +.fi +.SH DESCRIPTION +.BR nice () +adds +.I inc +to the nice value for the calling thread. +(A higher nice value means a lower priority.) +.PP +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. +.PP +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 +.B RLIMIT_NICE +soft limit; see +.BR getrlimit (2) +for details. +.SH RETURN VALUE +On success, the new nice value is returned (but see NOTES below). +On error, \-1 is returned, and +.I errno +is set to indicate the error. +.PP +A successful call can legitimately return \-1. +To detect an error, set +.I errno +to 0 before the call, and check whether it is nonzero after +.BR nice () +returns \-1. +.SH ERRORS +.TP +.B EPERM +The calling process attempted to increase its priority by +supplying a negative +.I inc +but has insufficient privileges. +Under Linux, the +.B CAP_SYS_NICE +capability is required. +(But see the discussion of the +.B RLIMIT_NICE +resource limit in +.BR setrlimit (2).) +.SH VERSIONS +.SS C library/kernel differences +POSIX.1 specifies that +.BR nice () +should return the new nice value. +However, the raw Linux system call returns 0 on success. +Likewise, the +.BR nice () +wrapper function provided in glibc 2.2.3 and earlier returns 0 on success. +.PP +Since glibc 2.2.4, the +.BR nice () +wrapper function provided by glibc provides conformance to POSIX.1 by calling +.BR getpriority (2) +to obtain the new nice value, which is then returned to the caller. +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001, SVr4, 4.3BSD. +.\" SVr4 documents an additional +.\" .B EINVAL +.\" error code. +.SH NOTES +For further details on the nice value, see +.BR sched (7). +.PP +.IR 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 +.BR sched (7). +.SH SEE ALSO +.BR nice (1), +.BR renice (1), +.BR fork (2), +.BR getpriority (2), +.BR getrlimit (2), +.BR setpriority (2), +.BR capabilities (7), +.BR sched (7) |