Ubuntu Manpage: This manual page is part of the POSIX Programmer's Manual. The Linux implementation of

Provided by: manpages-posix_2017a-2_all

PROLOG

       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

       renice — set nice values of running processes

SYNOPSIS

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

DESCRIPTION

       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.

OPTIONS

       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.

OPERANDS

       The following operands shall be supported:

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

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       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.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       Not used.

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       None.

EXAMPLES

        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

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.

FUTURE DIRECTIONS

       None.

COPYRIGHT

       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 .