Shell script to get the process ID on Linux

Question

I want to write a shell script   sh file  to get a given process id  What I m trying to do here is once I get the process ID  I want to kill that process  I m running on Ubuntu  Linux    I was able to do it with a command like  ps -aux grep ruby kill -9  lt pid gt    but I m not sure how to do it through a shell script

User · Accepted Answer

Using grep on the results of ps is a bad idea in a script  since some proportion of the time it will also match the grep process you ve just invoked   The command pgrep avoids this problem  so if you need to know the process ID  that s a better option    Note that  of course  there may be many processes matched    However  in your example  you could just use the similar command pkill to kill all matching processes   pkill ruby   Incidentally  you should be aware that using -9 is overkill  ho ho  in almost every case - there s some useful advice about that in the text of the  Useless Use of kill -9 form letter        No no no   Don t use kill -9       It doesn t give the process a chance to cleanly          shut down socket connections   clean up temp files   inform its children that it is going away   reset its terminal characteristics         and so on and so on and so on       Generally  send 15  and wait a second or two  and if that doesn t   work  send 2  and if that doesn t work  send 1   If that doesn t    REMOVE THE BINARY because the program is badly behaved       Don t use kill -9   Don t bring out the combine harvester just to tidy   up the flower pot

User · Answer

This works in Cygwin but it should be effective in Linux as well   ps -W   awk   ruby  NF 1    xargs kill -f   or  ps -W   awk   0 z NF 1  z ruby   xargs kill -f   Bash Pitfalls

User · Answer

You can use the command killall     killall ruby

User · Answer

option -v is very important  It can exclude a grep expression itself  e g   ps -w   grep sshd   grep -v grep   awk   print  1   to get sshd id

User · Answer

If you are going to use ps and grep then you should do it this way   ps aux grep r u by   Those square brackets will cause grep to skip the line for the grep command itself  So to use this in a script do   output  ps aux grep r  u  by  set --  output pid  2 kill  pid sleep 2 kill -9  pid  gt  dev null 2 gt  amp 1   The backticks allow you to capture the output of a comand in a shell variable  The set -- parses the ps output into words  and  2 is the second word on the line which happens to be the pid  Then you send a TERM signal  wait a couple of seconds for ruby to to shut itself down  then kill it mercilessly if it still exists  but throw away any output because most of the time kill -9 will complain that the process is already dead   I know that I have used this without the backslashes before the square brackets but just now I checked it on Ubuntu 12 and it seems to require them  This probably has something to do with bash s many options and the default config on different Linux distros  Hopefully the   and   will work anywhere but I no longer have access to the servers where I know that it worked without backslash so I cannot be sure   One comment suggests grep-v and that is what I used to do  but then when I learned of the    variant  I decided it was better to spawn one fewer process in the pipeline

User · Answer

To kill the process in shell  getprocess  ps -ef grep servername   echo  getprocess set  getprocess  pid  2  echo  pid kill -9  pid

User · Answer

Its pretty simple  Simply Run Any Program like this  - x  gedit  amp  echo    this will give you PID of this process  then do this kill -9  x

User · Answer

As a start there is no need to do a ps -aux   grep    The command pidof is far better to use  And almost never ever do kill -9 see here  to get the output from a command in bash  use something like  pid   pidof ruby    or use pkill directly

User · Answer

If you already know the process then this will be useful   PID  ps -eaf   grep  lt process gt    grep -v grep   awk   print  2    if             PID      then echo  killing  PID  kill -9  PID fi

[linux] Shell script to get the process ID on Linux

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