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RENICE(1P)		   POSIX Programmer's Manual		    RENICE(1P)

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.1‐2008, Section 3.240, Nice Value) of one
       or more running processes be changed. By default, the  applicable  pro‐
       cesses  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 request‐
       ing 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.1‐2008,  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 pro‐
		 cesses 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, depend‐
		 ing 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	 vari‐
		 ables	that are unset or null. (See the Base Definitions vol‐
		 ume of POSIX.1‐2008, Section 8.2, Internationalization	 Vari‐
		 ables	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  pro‐
       cesses in a system have priorities that are comparable. Scheduling pol‐
       icy 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 sys‐
       tem, 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 util‐
       ity was meant to do. Also, it would be  easier  to  document  what  the
       utility was meant to do. Unfortunately, the addition of the POSIX real‐
       time 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 individ‐
       ual 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.

SEE ALSO
       nice

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

COPYRIGHT
       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 Electri‐
       cal  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.ker‐
       nel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group		     2013			    RENICE(1P)
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