killing processes automatically

Question

I need to kill all processes in a certain shell, excluding certain processes.

For example, sh, which is my shell, and the command.

This is what is currently in my shell right now.

rcihp146 :/home/msingh2> ps
   PID TTY       TIME COMMAND
  8880 pts/258   0:00 ps
  5908 pts/258   0:00 sh

But if there are some extra processes I would like to kill all of them, excluding the above two.

I tried a one-liner for this purpose and it didn't work:

rcihp146 :/home/msingh2> ps | awk '{system("kill -9 $1")}'
sh: kill: The number of parameters specified is not correct.
sh: kill: The number of parameters specified is not correct.
sh: kill: The number of parameters specified is not correct.
sh: kill: The number of parameters specified is not correct.

... but it works if I only give a specific pid like below:

 rcihp146 :/home/msingh2> ps | awk '{system("kill -9 23456")}'

I need to exclude two or three process (like ps, sh) from being killed.

Is there any way to do this?

Answer 1

Of course the one liner you wrote won't work since the $1 is inside the quotes. Try this:

ps| gawk '{ if ($4 != "COMMAND" && $4 != "sh" && $4 != "ps") system("kill -KILL "$1) }'

Have fun but use it with caution. I generally don't like system commands in gawk, certainly not the "kill" command.

Answer 2

Rather than parse the output of ps, customize it to your liking.

If ps's filtering options are enough to make it show exactly the set of processes you want to kill, then specify -o pid= to only show the PID column, with no header line.

ps … -o pid=
 1234
56789

Since the output contains only digits and whitespace, you can use it directly in a command substitution:

kill $(ps … -o pid=)

If you need further processing, use -o to select the columns and order that you want. See the ps manual on your system for the supported column names; POSIX specifies a few. Add a = after each column to suppress the header line.

kill $(p=$(sh -c 'echo $PPID');
       ps -o pid= -o ppid= -o tty= -o comm= |
       awk -v "tty=${TTY#/dev/}" -v o=$$ -v p=$p '
           $1 != o && $1 != p && $2 != p && $3 == tty && $4 != "sh" {print $1}
       ')

Answer 3

If you need to do this sort of thing frequently, install proctools.

pkill -v -KILL ps

kills everything that isn't ps.