snice

NAME

       skill, snice - signal or reprioritize specified processes

SYNOPSIS

       skill [-signal] [-ivfwn] {tty user command pid}
       snice [(-|+)priority] [-ivfwn] {tty user command pid}
       skill -l

DESCRIPTION

       Skill  sends  the  terminate signal to a set of processes.
       If a signal name (or number) preceded by a `-'  is  given,
       that  signal  will be substituted for terminate.  The com-
       mand `skill -l' displays a list of available signals.

       Snice alters the  scheduling  priority  of  selected  pro-
       cesses.   By default, the new priority is +4, but an argu-
       ment of the form `+n' (or `-n') can  be  used  to  specify
       different  values.  An invalid priority is quietly rounded
       down (or up) to the first acceptable value.

       Options accepted by both commands are as follows:

       -i     In interactive mode, the user is prompted with each
              process that is a candidate for action.  Responding
              `y' will carry out the stated action.  Also,  a  ^D
              at  this prompt causes skill or snice to exit imme-
              diately.

       -v     In verbose mode, the id of  each  process  success-
              fully acted upon is displayed.

       -f     In  fast mode, the machine-dependent code responsi-
              ble for reading processes is allowed to make  deci-
              sions  to  improve  speed  at  the expense of error
              reporting (e.g. commands  may  not  be  displayed).
              This option mainly exists to aid in killing runaway
              processes on operating systems with complicated  VM
              designs.

       -w     Display warning messages for unreachable processes.

       -n     Display process id's but do not act on them.

       All command line arguments are order  independent.   Skill
       and snice allow processes to be specified using any combi-
       nation of ttys, user names, and commands (as well as  pro-
       cess  id's).   Only processes that match something in each
       category are acted upon.  An empty category  guarantees  a
       match.   For  example,  `skill -HUP vi ex tty00' will send
       the hangup signal to all vi(1) and ex(1) processes associ-
       ated  with  tty00.   Similarly, `snice +10 find root' will
       change the priority of all find(1) processes owned by root
       to +10.

       Unprivileged  users can only change their own processes so
       they need not specify their user name as part of the argu-
       ment  list.   On  the other hand, the super-user should be
       more careful (e.g. the command `snice -5 vi'  will  change
       the priority of every vi(1) process on the system).

       Since skill and snice categorize their arguments, there is
       a chance that they will do so incorrectly (e.g.  a  system
       command  is also a user name).  Both programs try to match
       an argument with a tty, a user name,  and  a  process  id,
       before  classifying it as a command.  To override this, an
       argument can be forced to a particular type  by  preceding
       it  with  "-c" (command), "-u" (user), "-t" (tty), or "-p"
       (process id).

       Process id's are not known beforehand, so both kernel mem-
       ory  and the swap device must be searched for the required
       information.  Alternately, on some  systems,  the  "/proc"
       file system is examined.  When a process fitting each cat-
       egory is discovered, it is immediately acted upon  (unless
       running  in  interactive  mode).  Processes must belong to
       the current user unless s/he is the  super-user.   Neither
       program  will  ever  act on itself, but everything else is
       fair game.

       Exit status is normally 0; if the user makes a mistake,  1
       is  returned.  If a system error occurs, exit status is 2.

FILES

       /vmunix        system name list
       /dev/mem       physical memory
       /dev/kmem      kernel virtual memory
       /dev/drum      swap device
       /proc          process file system
       /dev           searched to map ttys into device numbers

SEE ALSO

       kill(1), nice(1), priocntl(1), renice(1), ps(1),
       kill(2), setpriority(2), signal(2), proc(4)

AUTHOR

       Jeff Forys

CONTRIBUTORS

       David Sharnoff      Greg Earle          Christos Zoulas
       Gorodecki Tom       Mike Hibler         Ric Anderson

BUGS

       Things change while these programs  execute,  occasionally
       processes will be missed (the `-w' flag displays these).

       Command  names  may  be  truncated  to a machine-dependent
       size.

       On some operating systems, these programs  are  unable  to
       investigate processes belonging to other users.  While not
       a problem, this fact is reflected in the "(but N could not
       be  checked)"  notice, which follows the "no matching pro-
       cesses" message.