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)

PROLOG         top

       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.

NAME         top

       renice — set nice values of running processes

SYNOPSIS         top

       renice [−g|−p|−u] −n increment ID...

DESCRIPTION         top

       The renice utility shall request that the nice values (see the Base
       Definitions volume of POSIX.1‐2008, Section 3.240, 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.

OPTIONS         top

       The renice utility shall conform to the Base Definitions volume of
       POSIX.1‐2008, 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.

OPERANDS         top

       The following operands shall be supported:

       ID        A process ID, process group ID, or user name/user ID,
                 depending on the option selected.

STDIN         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.1‐2008, 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.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       Not used.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       None.

EXAMPLES         top

        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).

RATIONALE         top

       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.1‐2008 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.1‐2008, 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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       nice(1p)

       The Base Definitions volume of POSIX.1‐2008, Section 3.240, Nice
       Value, Chapter 8, Environment Variables, Section 12.2, Utility Syntax
       Guidelines

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/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                 2013                          RENICE(1P)

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