Find the PID(s) of running processes and store as an array

Question

I\'m trying to write a bash script to find the PID of a running process then issue a kill command. I have it partially working, but the issue I face is that there may be mor

Answer 1

Don't know why you would ever grep for a process to kill, unless you didn't know the command name. Most modern versions of ps have the flags

    -C cmdlist
          Select by command name.  This selects the processes whose executable name is given in cmdlist.

and

   -o format
          User-defined format.  format is a single argument in the form of
          a blank-separated or comma-separated list, which offers a way to
          specify individual output columns.  The recognized keywords are
          described in the STANDARD FORMAT SPECIFIERS section below.
          Headers may be renamed (ps -o pid,ruser=RealUser -o
          comm=Command) as desired.  If all column headers are empty (ps
          -o pid= -o comm=) then the header line will not be output.
          Column width will increase as needed for wide headers; this may
          be used to widen up columns such as WCHAN (ps -o pid,wchan=WIDE-
          WCHAN-COLUMN -o comm).  Explicit width control (ps opid,
          wchan:42,cmd) is offered too.  The behavior of ps -o pid=X,
          comm=Y varies with personality; output may be one column named
          "X,comm=Y" or two columns named "X" and "Y".  Use multiple -o
          options when in doubt.  Use the PS_FORMAT environment variable
          to specify a default as desired; DefSysV and DefBSD are macros
          that may be used to choose the default UNIX or BSD columns.

So you can just do

ps -o pid= -C commandName 

Will return the pid of all processes named exactly commandName and is cleaner and faster. Or kill a loop

while read -r pid; do 
  kill "$pid" 
done < <(ps -o pid= -C commandName)

But really, you should always just be able to do

> pkill commandName 

Answer 2

You don't need to use an array if you're going to immediately iterate over the results and perform an action:

for pid in $(ps -fe | grep '[p]rocess' | grep -v grep | awk '{print $2}'); do
    kill "$pid"
done

Notice we have to exclude grep's pid from the list of processes to kill. Or we could just use pgrep(1):

for pid in $(pgrep '[p]rocess'); do
    kill "$pid"
done

If you actually needed to store the pids in an array, pgrep is how you would do it:

pids=( $(pgrep '[p]rocess') )

Back to killing process. We can still do better. If we're just using pgrep to get a list of processes to kill them, why not go straight for pgrep's sister program: pkill(1)?

pkill '[p]rocess'

As it turns out, no need for bash scripting at all.

Answer 3

Your script seems fine, if you want to have each pid list on a new like then replace:

echo $pid
#kill $pid

with

echo "$pid"
#kill "$pid"

Answer 4

Here's a little one liner that might help

for pid in `ps -ef | grep your_search_term | awk '{print $2}'` ; do kill $pid ; done

Just replace your_search_term with the process name you want to kill.

You could also make it into a script and swap your_search_term for $1

EDIT: I suppose I should explain how this works.

The back ticks `` collects the output from the expression inside it. In this case it will return a list of pids for a process name.

Using a for loop we can iterate through each pid and kill the process.

EDIT2: replaced kill -9 with kill