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 nice(1)                                                             nice(1)




 NAME    [Toc]    [Back]
      nice - run a command at nondefault priority

 SYNOPSIS    [Toc]    [Back]
      nice [-priority_change] command [command_args]

      nice [-n priority_change] command [command_args]

 DESCRIPTION    [Toc]    [Back]
      The nice command executes command at a nondefault CPU scheduling
      priority.  (The name is derived from being "nice" to other system
      users by running large programs at lower priority.)

    Arguments    [Toc]    [Back]
      The command-line arguments are as follows:

           -n priority_change

           priority_change The difference between the system nice value
                           (relative priority) of the current (or parent)
                           process and the actual system nice value at which
                           command is to run.

                           An unsigned value increases the system nice value
                           for command, causing it to run at lower priority.

                           A negative value requires superuser privileges,
                           and assigns a lower system nice value (higher
                           priority) to command.  If the current process is
                           not privileged, the value is silently treated as
                           if it were 0.

                           If the value of priority_change would result in a
                           system nice value outside the range 0 through 39,
                           the corresponding limit value of 0 or 39 is used
                           instead.

                           Note that a positive priority_change (lower
                           priority) has a single - option character before
                           the numeric value; a negative (higher priority)
                           priority_change has two: the option character
                           followed by the minus sign (--).  If -
                           priority_change is not specified, it defaults to
                           10.

           command         A program, HP-UX command, user shell script, etc.
                           to be executed at the nondefault priority.
                           command can be run as a foreground or background
                           process.





 Hewlett-Packard Company            - 1 -   HP-UX 11i Version 2: August 2003






 nice(1)                                                             nice(1)




                           If command is run as a background process, any
                           nice priority_change made by the shell (ksh
                           executes all background processes via nice -4) is
                           in addition to that specified in the nice command
                           line.

           command_args    Any arguments recognized by command.

    Process Priorities    [Toc]    [Back]
      All processes have an associated system nice value which is used to
      compute the instantaneous-priority of the process when it is scheduled
      to run.  Normally, all processes inherit the system nice value of
      their parent process when they are spawned.  The shell (sh, csh, ksh,
      etc.) can create a child process with a different priority from the
      current shell process by spawning the child process via the nice
      command.  If the priority_change value is unsigned (positive), the
      child process is nicer (lower in priority) relative to the parent.  If
      the priority_change value is negative, the child process runs at a
      higher priority with a greater share of available system resources.
      To spawn a higher priority child process, the parent process must be
      owned by a user who has the appropriate privileges.

      At boot-up, the system starts the init process at a system nice value
      of 20 (system default).  On most systems, all processes (down to the
      login shells) inherit this priority.  Starting from their individual
      login shell processes, users can alter the system nice value of
      descendent processes to as much as 39, or, with appropriate
      privileges, as little as 0.  A system nice value of 0 establishes an
      extremely high priority, whereas a value of 39 indicates a very low
      priority.

      Ordinary users can only increase the system nice value of any child
      process relative to the current process; i.e., priority_change must be
      a positive (unsigned) value, resulting in a lower priority.  To start
      a child process at a lower system nice value (higher priority) than
      the current process, the user must have the appropriate privileges,
      regardless of the relative nice-priority value desired.

      For example, using the command

           nice ksh

      from a login shell whose current nice value is 20 spawns a subshell
      with a system nice value of 30.  Attempting to use

           nice --2 ksh

      from the new shell to spawn another subshell whose system nice value
      would be 28, is rejected (unless the user has appropriate privileges),
      even though the resulting system nice value would be less than the
      priority of the original login shell process.



 Hewlett-Packard Company            - 2 -   HP-UX 11i Version 2: August 2003






 nice(1)                                                             nice(1)




      The system nice value for current processes is listed under the NI
      column produced by the ps -l command (see ps(1)).

    Background Processes    [Toc]    [Back]
      Foreground processes are run at same system nice value as the parent
      shell.  Background processes spawned by ksh run at the equivalent of a
      nice -4 by default.  If a background process is started via nice from
      ksh, any priority_change specified in the nice command is added to
      default nice -4.  Thus the command

           nice 12 command &

      runs at a system nice value of 36 if executed from ksh.

 EXTERNAL INFLUENCES    [Toc]    [Back]
    Environment Variables
      LC_MESSAGES determines the language in which messages are displayed.

      If LC_MESSAGES is not specified in the environment or is set to the
      empty string, the value of LANG is used as a default for each
      unspecified or empty variable.  If LANG is not specified or is set to
      the empty string, a default of "C" (see lang(5)) is used instead of
      LANG.

      If any internationalization variable contains an invalid setting, nice
      behaves as if all internationalization variables are set to "C".  See
      environ(5).

    International Code Set Support    [Toc]    [Back]
      Single- and multi-byte character code sets are supported.

 RETURN VALUE    [Toc]    [Back]
      nice returns the value returned by command.

 EXAMPLES    [Toc]    [Back]
      The following examples assume the current process is running with a
      system nice value of 20 and nice is executed from the Korn shell (see
      ksh(1)).

      Run a program named prog in the current directory at the default
      priority_change of 10 (system nice value of 30):

           nice ./prog prog_args

      Run the same program in the background using a system nice value of 36
      (priority_change=12 plus 4 for the Korn shell):

           nice -12 ./prog prog_args &

      As a user with appropriate privileges, run prog as a foreground
      process with a system nice value of 6:



 Hewlett-Packard Company            - 3 -   HP-UX 11i Version 2: August 2003






 nice(1)                                                             nice(1)




           nice --14 ./prog prog_args

 WARNINGS    [Toc]    [Back]
      The C shell, csh, has a built-in nice command with different syntax.
      See csh(1) for details.

 SEE ALSO    [Toc]    [Back]
      csh(1), ksh(1), nohup(1), sh-posix(1), sh(1), renice(1M), nice(2).

 STANDARDS CONFORMANCE    [Toc]    [Back]
      nice: SVID2, SVID3, XPG4


 Hewlett-Packard Company            - 4 -   HP-UX 11i Version 2: August 2003
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