php man page for nice

NICE(1)                                                            User Commands                                                           NICE(1)

NAME
       nice - run a program with modified scheduling priority

SYNOPSIS
       nice [OPTION] [COMMAND [ARG]...]

DESCRIPTION
       Run  COMMAND  with  an  adjusted niceness, which affects process scheduling.  With no COMMAND, print the current niceness.  Niceness values
       range from -20 (most favorable to the process) to 19 (least favorable to the process).

       Mandatory arguments to long options are mandatory for short options too.

       -n, --adjustment=N
              add integer N to the niceness (default 10)

       --help display this help and exit

       --version
              output version information and exit

       NOTE: your shell may have its own version of nice, which usually supersedes the version described here.  Please refer to your shell's docu-
       mentation for details about the options it supports.

AUTHOR
       Written by David MacKenzie.

REPORTING BUGS
       GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
       Report nice translation bugs to <http://translationproject.org/team/>

COPYRIGHT
       Copyright (C) 2017 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       nice(2), renice(1)

       Full documentation at: <http://www.gnu.org/software/coreutils/nice>
       or available locally via: info '(coreutils) nice invocation'

GNU coreutils 8.28                                                 January 2018                                                            NICE(1)