1RENICE(1P) POSIX Programmer's Manual RENICE(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 renice — set nice values of running processes
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15 renice [-g|-p|-u] -n increment ID...
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18 The renice utility shall request that the nice values (see the Base
19 Definitions volume of POSIX.1‐2017, Section 3.244, Nice Value) of one
20 or more running processes be changed. By default, the applicable pro‐
21 cesses are specified by their process IDs. When a process group is
22 specified (see -g), the request shall apply to all processes in the
23 process group.
24 The nice value shall be bounded in an implementation-defined manner.
26 If the requested increment would raise or lower the nice value of the
27 executed utility beyond implementation-defined limits, then the limit
28 whose value was exceeded shall be used.
29 When a user is reniced, the request applies to all processes whose
31 saved set-user-ID matches the user ID corresponding to the user.
32 Regardless of which options are supplied or any other factor, renice
34 shall not alter the nice values of any process unless the user request‐
35 ing such a change has appropriate privileges to do so for the specified
36 process. If the user lacks appropriate privileges to perform the
37 requested action, the utility shall return an error status.
38 The saved set-user-ID of the user's process shall be checked instead of
40 its effective user ID when renice attempts to determine the user ID of
41 the process in order to determine whether the user has appropriate
42 privileges.
43
45 The renice utility shall conform to the Base Definitions volume of
46 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines, except for
47 Guideline 9.
48 The following options shall be supported:
50 -g Interpret the following operands as unsigned decimal integer
52 process group IDs.
53 -n increment
55 Specify how the nice value of the specified process or pro‐
56 cesses is to be adjusted. The increment option-argument is a
57 positive or negative decimal integer that shall be used to
58 modify the nice value of the specified process or processes.
59 Positive increment values shall cause a lower nice value.
61 Negative increment values may require appropriate privileges
62 and shall cause a higher nice value.
63 -p Interpret the following operands as unsigned decimal integer
65 process IDs. The -p option is the default if no options are
66 specified.
67 -u Interpret the following operands as users. If a user exists
69 with a user name equal to the operand, then the user ID of
70 that user is used in further processing. Otherwise, if the
71 operand represents an unsigned decimal integer, it shall be
72 used as the numeric user ID of the user.
73
75 The following operands shall be supported:
76 ID A process ID, process group ID, or user name/user ID, depend‐
78 ing on the option selected.
79
81 Not used.
82
84 None.
85
87 The following environment variables shall affect the execution of
88 renice:
89 LANG Provide a default value for the internationalization vari‐
91 ables that are unset or null. (See the Base Definitions vol‐
92 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
93 ables for the precedence of internationalization variables
94 used to determine the values of locale categories.)
95 LC_ALL If set to a non-empty string value, override the values of
97 all the other internationalization variables.
98 LC_CTYPE Determine the locale for the interpretation of sequences of
100 bytes of text data as characters (for example, single-byte as
101 opposed to multi-byte characters in arguments).
102 LC_MESSAGES
104 Determine the locale that should be used to affect the format
105 and contents of diagnostic messages written to standard
106 error.
107 NLSPATH Determine the location of message catalogs for the processing
109 of LC_MESSAGES.
110
112 Default.
113
115 Not used.
116
118 The standard error shall be used only for diagnostic messages.
119
121 None.
122
124 None.
125
127 The following exit values shall be returned:
128 0 Successful completion.
130 >0 An error occurred.
132
134 Default.
135 The following sections are informative.
137
139 None.
140
142 1. Adjust the nice value so that process IDs 987 and 32 would have a
143 lower nice value:
144 renice -n 5 -p 987 32
147 2. Adjust the nice value so that group IDs 324 and 76 would have a
149 higher nice value, if the user has appropriate privileges to do so:
150 renice -n -4 -g 324 76
153 3. Adjust the nice value so that numeric user ID 8 and user sas would
155 have a lower nice value:
156 renice -n 4 -u 8 sas
159 Useful nice value increments on historical systems include 19 or 20
161 (the affected processes run only when nothing else in the system
162 attempts to run) and any negative number (to make processes run
163 faster).
164
166 The gid, pid, and user specifications do not fit either the definition
167 of operand or option-argument. However, for clarity, they have been
168 included in the OPTIONS section, rather than the OPERANDS section.
169 The definition of nice value is not intended to suggest that all pro‐
171 cesses in a system have priorities that are comparable. Scheduling pol‐
172 icy extensions such as the realtime priorities in the System Interfaces
173 volume of POSIX.1‐2017 make the notion of a single underlying priority
174 for all scheduling policies problematic. Some implementations may
175 implement the nice-related features to affect all processes on the sys‐
176 tem, others to affect just the general time-sharing activities implied
177 by this volume of POSIX.1‐2017, and others may have no effect at all.
178 Because of the use of ``implementation-defined'' in nice and renice, a
179 wide range of implementation strategies are possible.
180 Originally, this utility was written in the historical manner, using
182 the term ``nice value''. This was always a point of concern with users
183 because it was never intuitively obvious what this meant. With a newer
184 version of renice, which used the term ``system scheduling priority'',
185 it was hoped that novice users could better understand what this util‐
186 ity was meant to do. Also, it would be easier to document what the
187 utility was meant to do. Unfortunately, the addition of the POSIX real‐
188 time scheduling capabilities introduced the concepts of process and
189 thread scheduling priorities that were totally unaffected by the
190 nice/renice utilities or the nice()/setpriority() functions. Continuing
191 to use the term ``system scheduling priority'' would have incorrectly
192 suggested that these utilities and functions were indeed affecting
193 these realtime priorities. It was decided to revert to the historical
194 term ``nice value'' to reference this unrelated process attribute.
195 Although this utility has use by system administrators (and in fact
197 appears in the system administration portion of the BSD documentation),
198 the standard developers considered that it was very useful for individ‐
199 ual end users to control their own processes.
200 Earlier versions of this standard allowed the following forms in the
202 SYNOPSIS:
203 renice nice_value[-p] pid...[-g gid...][-p pid...][-u user...]
206 renice nice_value -g gid...[-g gid...]-p pid...][-u user...]
207 renice nice_value -u user...[-g gid...]-p pid...][-u user...]
208 These forms are no longer specified by POSIX.1‐2008 but may be present
210 in some implementations.
211
213 None.
214
216 nice
217 The Base Definitions volume of POSIX.1‐2017, Section 3.244, Nice Value,
219 Chapter 8, Environment Variables, Section 12.2, Utility Syntax Guide‐
220 lines
221
223 Portions of this text are reprinted and reproduced in electronic form
224 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
225 table Operating System Interface (POSIX), The Open Group Base Specifi‐
226 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
227 Electrical and Electronics Engineers, Inc and The Open Group. In the
228 event of any discrepancy between this version and the original IEEE and
229 The Open Group Standard, the original IEEE and The Open Group Standard
230 is the referee document. The original Standard can be obtained online
231 at http://www.opengroup.org/unix/online.html .
232 Any typographical or formatting errors that appear in this page are
234 most likely to have been introduced during the conversion of the source
235 files to man page format. To report such errors, see https://www.ker‐
236 nel.org/doc/man-pages/reporting_bugs.html .
237IEEE/The Open Group 2017 RENICE(1P)