|
HTML rendering created 2023-12-22 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. |
|
|
PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
|
|
|
RENICE(1P) POSIX Programmer's Manual RENICE(1P)
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.
renice — set nice values of running processes
renice [-g|-p|-u] -n increment ID...
The renice utility shall request that the nice values (see the
Base Definitions volume of POSIX.1‐2017, Section 3.244, Nice
Value) of one or more running processes be changed. By default,
the applicable processes are specified by their process IDs. When
a process group is specified (see -g), the request shall apply to
all processes in the process group.
The nice value shall be bounded in an implementation-defined
manner. If the requested increment would raise or lower the nice
value of the executed utility beyond implementation-defined
limits, then the limit whose value was exceeded shall be used.
When a user is reniced, the request applies to all processes
whose saved set-user-ID matches the user ID corresponding to the
user.
Regardless of which options are supplied or any other factor,
renice shall not alter the nice values of any process unless the
user requesting such a change has appropriate privileges to do so
for the specified process. If the user lacks appropriate
privileges to perform the requested action, the utility shall
return an error status.
The saved set-user-ID of the user's process shall be checked
instead of its effective user ID when renice attempts to
determine the user ID of the process in order to determine
whether the user has appropriate privileges.
The renice utility shall conform to the Base Definitions volume
of POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines, except
for Guideline 9.
The following options shall be supported:
-g Interpret the following operands as unsigned decimal
integer process group IDs.
-n increment
Specify how the nice value of the specified process or
processes is to be adjusted. The increment option-
argument is a positive or negative decimal integer that
shall be used to modify the nice value of the specified
process or processes.
Positive increment values shall cause a lower nice
value. Negative increment values may require
appropriate privileges and shall cause a higher nice
value.
-p Interpret the following operands as unsigned decimal
integer process IDs. The -p option is the default if no
options are specified.
-u Interpret the following operands as users. If a user
exists with a user name equal to the operand, then the
user ID of that user is used in further processing.
Otherwise, if the operand represents an unsigned
decimal integer, it shall be used as the numeric user
ID of the user.
The following operands shall be supported:
ID A process ID, process group ID, or user name/user ID,
depending on the option selected.
Not used.
None.
The following environment variables shall affect the execution of
renice:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
Not used.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
None.
1. Adjust the nice value so that process IDs 987 and 32 would
have a lower nice value:
renice -n 5 -p 987 32
2. Adjust the nice value so that group IDs 324 and 76 would have
a higher nice value, if the user has appropriate privileges
to do so:
renice -n -4 -g 324 76
3. Adjust the nice value so that numeric user ID 8 and user sas
would have a lower nice value:
renice -n 4 -u 8 sas
Useful nice value increments on historical systems include 19 or
20 (the affected processes run only when nothing else in the
system attempts to run) and any negative number (to make
processes run faster).
The gid, pid, and user specifications do not fit either the
definition of operand or option-argument. However, for clarity,
they have been included in the OPTIONS section, rather than the
OPERANDS section.
The definition of nice value is not intended to suggest that all
processes in a system have priorities that are comparable.
Scheduling policy extensions such as the realtime priorities in
the System Interfaces volume of POSIX.1‐2017 make the notion of a
single underlying priority for all scheduling policies
problematic. Some implementations may implement the nice-related
features to affect all processes on the system, others to affect
just the general time-sharing activities implied by this volume
of POSIX.1‐2017, and others may have no effect at all. Because of
the use of ``implementation-defined'' in nice and renice, a wide
range of implementation strategies are possible.
Originally, this utility was written in the historical manner,
using the term ``nice value''. This was always a point of concern
with users because it was never intuitively obvious what this
meant. With a newer version of renice, which used the term
``system scheduling priority'', it was hoped that novice users
could better understand what this utility was meant to do. Also,
it would be easier to document what the utility was meant to do.
Unfortunately, the addition of the POSIX realtime scheduling
capabilities introduced the concepts of process and thread
scheduling priorities that were totally unaffected by the
nice/renice utilities or the nice()/setpriority() functions.
Continuing to use the term ``system scheduling priority'' would
have incorrectly suggested that these utilities and functions
were indeed affecting these realtime priorities. It was decided
to revert to the historical term ``nice value'' to reference this
unrelated process attribute.
Although this utility has use by system administrators (and in
fact appears in the system administration portion of the BSD
documentation), the standard developers considered that it was
very useful for individual end users to control their own
processes.
Earlier versions of this standard allowed the following forms in
the SYNOPSIS:
renice nice_value[-p] pid...[-g gid...][-p pid...][-u user...]
renice nice_value -g gid...[-g gid...]-p pid...][-u user...]
renice nice_value -u user...[-g gid...]-p pid...][-u user...]
These forms are no longer specified by POSIX.1‐2008 but may be
present in some implementations.
None.
nice(1p)
The Base Definitions volume of POSIX.1‐2017, Section 3.244, Nice
Value, Chapter 8, Environment Variables, Section 12.2, Utility
Syntax Guidelines
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 RENICE(1P)
Pages that refer to this page: nice(1p), ps(1p)
|
HTML rendering created 2023-12-22 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. |
|