diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/coreutils.texi | 56 |
1 files changed, 33 insertions, 23 deletions
diff --git a/doc/coreutils.texi b/doc/coreutils.texi index b0dfa57cb..ef9767cf3 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -11997,29 +11997,35 @@ the exit status of @var{command} otherwise @section @command{nice}: Run a command with modified scheduling priority @pindex nice +@cindex nice value @cindex modifying scheduling priority @cindex scheduling priority, modifying @cindex priority, modifying @cindex appropriate privileges -@command{nice} prints or modifies the scheduling priority of a job. +@command{nice} prints or modifies a process's @dfn{nice value}, +a parameter that affects the process's scheduling priority. Synopsis: @example nice [@var{option}]@dots{} [@var{command} [@var{arg}]@dots{}] @end example -If no arguments are given, @command{nice} prints the current scheduling -priority, which it inherited. Otherwise, @command{nice} runs the given -@var{command} with its scheduling priority adjusted. If no -@var{adjustment} is given, the priority of the command is incremented by -10. You must have appropriate privileges to specify a negative -adjustment. The priority can be adjusted by @command{nice} over the range -of @minus{}20 (the highest priority) to 19 (the lowest). +If no arguments are given, @command{nice} prints the current nice +value, which it inherited. Otherwise, @command{nice} runs the given +@var{command} with its nice value adjusted. By default, its nice +value is incremented by 10. + +Nice values range at least from @minus{}20 (resulting in the most +favorable scheduling) through 19 (the least favorable). Some systems +may have a wider range of nice values; conversely, other systems may +enforce more restrictive limits. An attempt to set the nice value +outside the supported range is treated as an attempt to use the +minimum or maximum supported value. @cindex conflicts with shell built-ins @cindex built-in shell commands, conflicts with -Because most shells have a built-in command by the same name, using the +Because many shells have a built-in command by the same name, using the unadorned command name in a script or interactively may get you different functionality than that described here. @@ -12030,7 +12036,10 @@ The program accepts the following option. Also see @ref{Common options}. @itemx --adjustment=@var{adjustment} @opindex -n @opindex --adjustment -Add @var{adjustment} instead of 10 to the command's priority. +Add @var{adjustment} instead of 10 to the command's nice value. If +@var{adjustment} is negative and you lack appropriate privileges, +@command{nice} issues a warning but otherwise acts as if you specified +a zero adjustment. On older systems, @command{nice} supports an obsolete option @option{-@var{adjustment}}. @acronym{POSIX} 1003.1-2001 (@pxref{Standards @@ -12053,46 +12062,47 @@ the exit status of @var{command} otherwise It is sometimes useful to run non-interactive programs with reduced priority. @example -$ nice factor `echo '2^997 - 1'|bc` +$ nice factor 4611686018427387903 @end example Since @command{nice} prints the current priority, -we can invoke it through itself to demonstrate how it works: +you can invoke it through itself to demonstrate how it works. -The default behavior is to reduce priority by @samp{10}. +The default behavior is to increase the nice value by @samp{10}: @example +$ nice +0 $ nice nice 10 -@end example - -@example $ nice -n 10 nice 10 @end example -The @var{adjustment} is relative to the current priority. -Here, the first @command{nice} invocation runs the second one at priority -@samp{10}, and it in turn runs the final one at a priority lowered by -@samp{3} more. +The @var{adjustment} is relative to the current nice value. In the +next example, the first @command{nice} invocation runs the second one +with nice value 10, and it in turn runs the final one with a nice +value that is 3 more: @example $ nice nice -n 3 nice 13 @end example -Specifying a priority larger than @samp{19} is the same as specifying @samp{19}. +Specifying a nice value larger than the supported range +is the same as specifying the maximum supported value: @example -$ nice -n 30 nice +$ nice -n 10000000000 nice 19 @end example -Only a privileged user may run a process with higher priority. +Only a privileged user may run a process with higher priority: @example $ nice -n -1 nice nice: cannot set priority: Permission denied +0 $ sudo nice -n -1 nice -1 @end example |