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