mirror of https://github.com/mkerrisk/man-pages
252 lines
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Groff
252 lines
8.0 KiB
Groff
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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "RENICE" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" renice
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.SH NAME
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renice \- set nice values of running processes
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.SH SYNOPSIS
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.LP
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\fBrenice -n\fP \fIincrement\fP \fB[\fP\fB-g | -p | -u\fP\fB]\fP \fIID\fP
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\fB\&... \fP
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.SH DESCRIPTION
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.LP
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The \fIrenice\fP utility shall request that the nice values (see the
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Base Definitions volume of IEEE\ Std\ 1003.1-2001,
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Section 3.239, Nice Value) of one or more running processes be changed.
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By
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default, the applicable processes are specified by their process IDs.
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When a process group is specified (see \fB-g\fP), the
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request shall apply to all processes in the process group.
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.LP
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The nice value shall be bounded in an implementation-defined manner.
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If the requested \fIincrement\fP would raise or lower the
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nice value of the executed utility beyond implementation-defined limits,
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then the limit whose value was exceeded shall be used.
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.LP
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When a user is \fIrenice\fPd, the request applies to all processes
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whose saved set-user-ID matches the user ID corresponding to
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the user.
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.LP
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Regardless of which options are supplied or any other factor, \fIrenice\fP
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shall not alter the nice values of any process
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unless the user requesting such a change has appropriate privileges
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to do so for the specified process. If the user lacks
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appropriate privileges to perform the requested action, the utility
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shall return an error status.
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.LP
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The saved set-user-ID of the user's process shall be checked instead
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of its effective user ID when \fIrenice\fP attempts to
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determine the user ID of the process in order to determine whether
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the user has appropriate privileges.
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.SH OPTIONS
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.LP
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The \fIrenice\fP utility shall conform to the Base Definitions volume
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of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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.LP
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The following options shall be supported:
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.TP 7
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\fB-g\fP
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Interpret all operands as unsigned decimal integer process group IDs.
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.TP 7
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\fB-n\ \fP \fIincrement\fP
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Specify how the nice value of the specified process or processes is
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to be adjusted. The \fIincrement\fP option-argument is a
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positive or negative decimal integer that shall be used to modify
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the nice value of the specified process or processes.
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.LP
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Positive \fIincrement\fP values shall cause a lower nice value. Negative
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\fIincrement\fP values may require appropriate
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privileges and shall cause a higher nice value.
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.TP 7
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\fB-p\fP
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Interpret all operands as unsigned decimal integer process IDs. The
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\fB-p\fP option is the default if no options are
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specified.
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.TP 7
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\fB-u\fP
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Interpret all operands as users. If a user exists with a user name
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equal to the operand, then the user ID of that user is used
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in further processing. Otherwise, if the operand represents an unsigned
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decimal integer, it shall be used as the numeric user ID of
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the user.
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.sp
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.SH OPERANDS
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.LP
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The following operands shall be supported:
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.TP 7
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\fIID\fP
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A process ID, process group ID, or user name/user ID, depending on
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the option selected.
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.sp
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.SH STDIN
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.LP
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Not used.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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The following environment variables shall affect the execution of
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\fIrenice\fP:
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.TP 7
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\fILANG\fP
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Provide a default value for the internationalization variables that
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are unset or null. (See the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
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for
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the precedence of internationalization variables used to determine
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the values of locale categories.)
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.TP 7
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\fILC_ALL\fP
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If set to a non-empty string value, override the values of all the
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other internationalization variables.
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.TP 7
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\fILC_CTYPE\fP
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Determine the locale for the interpretation of sequences of bytes
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of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).
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.TP 7
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\fILC_MESSAGES\fP
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Determine the locale that should be used to affect the format and
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contents of diagnostic messages written to standard
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error.
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.TP 7
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\fINLSPATH\fP
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Determine the location of message catalogs for the processing of \fILC_MESSAGES
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\&.\fP
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.sp
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default.
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.SH STDOUT
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.LP
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Not used.
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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None.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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The following exit values shall be returned:
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.TP 7
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\ 0
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Successful completion.
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.TP 7
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>0
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An error occurred.
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.sp
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.SH CONSEQUENCES OF ERRORS
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.LP
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Default.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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None.
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.SH EXAMPLES
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.IP " 1." 4
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Adjust the nice value so that process IDs 987 and 32 would have a
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lower nice value:
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.sp
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.RS
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.nf
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\fBrenice -n 5 -p 987 32
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\fP
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.fi
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.RE
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.LP
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.IP " 2." 4
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Adjust the nice value so that group IDs 324 and 76 would have a higher
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nice value, if the user has the appropriate privileges to
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do so:
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.sp
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.RS
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.nf
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\fBrenice -n -4 -g 324 76
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\fP
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.fi
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.RE
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.LP
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.IP " 3." 4
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Adjust the nice value so that numeric user ID 8 and user \fBsas\fP
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would have a lower nice value:
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.sp
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.RS
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.nf
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\fBrenice -n 4 -u 8 sas
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\fP
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.fi
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.RE
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.LP
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.LP
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Useful nice value increments on historical systems include 19 or 20
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(the affected processes run only when nothing else in the
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system attempts to run) and any negative number (to make processes
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run faster).
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.SH RATIONALE
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.LP
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The \fIgid\fP, \fIpid\fP, and \fIuser\fP specifications do not fit
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either the definition of operand or option-argument.
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However, for clarity, they have been included in the OPTIONS section,
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rather than the OPERANDS section.
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.LP
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The definition of nice value is not intended to suggest that all processes
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in a system have priorities that are comparable.
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Scheduling policy extensions such as the realtime priorities in the
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System Interfaces volume of IEEE\ Std\ 1003.1-2001 make
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the notion of a single underlying priority for all scheduling policies
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problematic. Some implementations may implement the \fInice\fP-related
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features to affect all processes on the system, others to affect just
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the general
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time-sharing activities implied by this volume of IEEE\ Std\ 1003.1-2001,
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and others may have no effect at all. Because of
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the use of "implementation-defined" in \fInice\fP and \fIrenice\fP,
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a wide range of
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implementation strategies are possible.
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.LP
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Originally, this utility was written in the historical manner, using
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the term "nice value". This was always a point of concern
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with users because it was never intuitively obvious what this meant.
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With a newer version of \fIrenice\fP, which used the term
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"system scheduling priority", it was hoped that novice users could
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better understand what this utility was meant to do. Also, it
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would be easier to document what the utility was meant to do. Unfortunately,
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the addition of the POSIX realtime scheduling
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capabilities introduced the concepts of process and thread scheduling
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priorities that were totally unaffected by the \fInice\fP/ \fIrenice\fP
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utilities or the \fInice\fP()/ \fIsetpriority\fP() functions. Continuing
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to use the term "system scheduling priority''
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would have incorrectly suggested that these utilities and functions
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were indeed affecting these realtime priorities. It was decided
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to revert to the historical term "nice value" to reference this unrelated
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process attribute.
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.LP
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Although this utility has use by system administrators (and in fact
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appears in the system administration portion of the BSD
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documentation), the standard developers considered that it was very
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useful for individual end users to control their own
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processes.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fInice\fP()
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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