1RENICE(1P) POSIX Programmer's Manual RENICE(1P)
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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.
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13 renice — set nice values of running processes
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16 renice [−g|−p|−u] −n increment ID...
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19 The renice utility shall request that the nice values (see the Base
20 Definitions volume of POSIX.1‐2008, Section 3.240, Nice Value) of one
21 or more running processes be changed. By default, the applicable pro‐
22 cesses are specified by their process IDs. When a process group is
23 specified (see −g), the request shall apply to all processes in the
24 process group.
25 The nice value shall be bounded in an implementation-defined manner.
27 If the requested increment would raise or lower the nice value of the
28 executed utility beyond implementation-defined limits, then the limit
29 whose value was exceeded shall be used.
30 When a user is reniced, the request applies to all processes whose
32 saved set-user-ID matches the user ID corresponding to the user.
33 Regardless of which options are supplied or any other factor, renice
35 shall not alter the nice values of any process unless the user request‐
36 ing such a change has appropriate privileges to do so for the specified
37 process. If the user lacks appropriate privileges to perform the
38 requested action, the utility shall return an error status.
39 The saved set-user-ID of the user's process shall be checked instead of
41 its effective user ID when renice attempts to determine the user ID of
42 the process in order to determine whether the user has appropriate
43 privileges.
44
46 The renice utility shall conform to the Base Definitions volume of
47 POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines, except for
48 Guideline 9.
49 The following options shall be supported:
51 −g Interpret the following operands as unsigned decimal integer
53 process group IDs.
54 −n increment
56 Specify how the nice value of the specified process or pro‐
57 cesses is to be adjusted. The increment option-argument is a
58 positive or negative decimal integer that shall be used to
59 modify the nice value of the specified process or processes.
60 Positive increment values shall cause a lower nice value.
62 Negative increment values may require appropriate privileges
63 and shall cause a higher nice value.
64 −p Interpret the following operands as unsigned decimal integer
66 process IDs. The −p option is the default if no options are
67 specified.
68 −u Interpret the following operands as users. If a user exists
70 with a user name equal to the operand, then the user ID of
71 that user is used in further processing. Otherwise, if the
72 operand represents an unsigned decimal integer, it shall be
73 used as the numeric user ID of the user.
74
76 The following operands shall be supported:
77 ID A process ID, process group ID, or user name/user ID, depend‐
79 ing on the option selected.
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82 Not used.
83
85 None.
86
88 The following environment variables shall affect the execution of
89 renice:
90 LANG Provide a default value for the internationalization vari‐
92 ables that are unset or null. (See the Base Definitions vol‐
93 ume of POSIX.1‐2008, Section 8.2, Internationalization Vari‐
94 ables for the precedence of internationalization variables
95 used to determine the values of locale categories.)
96 LC_ALL If set to a non-empty string value, override the values of
98 all the other internationalization variables.
99 LC_CTYPE Determine the locale for the interpretation of sequences of
101 bytes of text data as characters (for example, single-byte as
102 opposed to multi-byte characters in arguments).
103 LC_MESSAGES
105 Determine the locale that should be used to affect the format
106 and contents of diagnostic messages written to standard
107 error.
108 NLSPATH Determine the location of message catalogs for the processing
110 of LC_MESSAGES.
111
113 Default.
114
116 Not used.
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119 The standard error shall be used only for diagnostic messages.
120
122 None.
123
125 None.
126
128 The following exit values shall be returned:
129 0 Successful completion.
131 >0 An error occurred.
133
135 Default.
136 The following sections are informative.
138
140 None.
141
143 1. Adjust the nice value so that process IDs 987 and 32 would have a
144 lower nice value:
145 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
152 3. Adjust the nice value so that numeric user ID 8 and user sas would
154 have a lower nice value:
155 renice −n 4 −u 8 sas
157 Useful nice value increments on historical systems include 19 or 20
159 (the affected processes run only when nothing else in the system
160 attempts to run) and any negative number (to make processes run
161 faster).
162
164 The gid, pid, and user specifications do not fit either the definition
165 of operand or option-argument. However, for clarity, they have been
166 included in the OPTIONS section, rather than the OPERANDS section.
167 The definition of nice value is not intended to suggest that all pro‐
169 cesses in a system have priorities that are comparable. Scheduling pol‐
170 icy extensions such as the realtime priorities in the System Interfaces
171 volume of POSIX.1‐2008 make the notion of a single underlying priority
172 for all scheduling policies problematic. Some implementations may
173 implement the nice-related features to affect all processes on the sys‐
174 tem, others to affect just the general time-sharing activities implied
175 by this volume of POSIX.1‐2008, and others may have no effect at all.
176 Because of the use of ``implementation-defined'' in nice and renice, a
177 wide range of implementation strategies are possible.
178 Originally, this utility was written in the historical manner, using
180 the term ``nice value''. This was always a point of concern with users
181 because it was never intuitively obvious what this meant. With a newer
182 version of renice, which used the term ``system scheduling priority'',
183 it was hoped that novice users could better understand what this util‐
184 ity was meant to do. Also, it would be easier to document what the
185 utility was meant to do. Unfortunately, the addition of the POSIX real‐
186 time scheduling capabilities introduced the concepts of process and
187 thread scheduling priorities that were totally unaffected by the
188 nice/renice utilities or the nice()/setpriority() functions. Continuing
189 to use the term ``system scheduling priority'' would have incorrectly
190 suggested that these utilities and functions were indeed affecting
191 these realtime priorities. It was decided to revert to the historical
192 term ``nice value'' to reference this unrelated process attribute.
193 Although this utility has use by system administrators (and in fact
195 appears in the system administration portion of the BSD documentation),
196 the standard developers considered that it was very useful for individ‐
197 ual end users to control their own processes.
198 Earlier versions of this standard allowed the following forms in the
200 SYNOPSIS:
201 renice nice_value[−p] pid...[−g gid...][−p pid...][−u user...]
203 renice nice_value −g gid...[−g gid...]−p pid...][−u user...]
204 renice nice_value −u user...[−g gid...]−p pid...][−u user...]
205 These forms are no longer specified by POSIX.1‐2008 but may be present
207 in some implementations.
208
210 None.
211
213 nice
214 The Base Definitions volume of POSIX.1‐2008, Section 3.240, Nice Value,
216 Chapter 8, Environment Variables, Section 12.2, Utility Syntax Guide‐
217 lines
218
220 Portions of this text are reprinted and reproduced in electronic form
221 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
222 -- Portable Operating System Interface (POSIX), The Open Group Base
223 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
224 cal and Electronics Engineers, Inc and The Open Group. (This is
225 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
226 event of any discrepancy between this version and the original IEEE and
227 The Open Group Standard, the original IEEE and The Open Group Standard
228 is the referee document. The original Standard can be obtained online
229 at http://www.unix.org/online.html .
230 Any typographical or formatting errors that appear in this page are
232 most likely to have been introduced during the conversion of the source
233 files to man page format. To report such errors, see https://www.ker‐
234 nel.org/doc/man-pages/reporting_bugs.html .
235IEEE/The Open Group 2013 RENICE(1P)