What s the best way to send a signal to all members of a process group

Question

I want to kill a whole process tree   What is the best way to do this using any common scripting languages  I am looking for a simple solution

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Inspired by ysth   s comment  kill -- -PGID      instead of giving it a process number  give it the negation of the group   number  As usual with almost any command  if you want a normal argument that   starts with a - to not be interpreted as a switch  precede it with --

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Here is a variation of  zhigang s answer which does without AWK  relying only on Bash s native parsing possibilities   function killtree     kill -STOP   1    ps -e -o pid  -o ppid    while read -r pid ppid                            do                                  ppid    1       continue                              killtree   pid      true   Skip over failures                            done   kill -CONT   1              kill -TERM   1      It seems to work fine on both Macs and Linux  In situations where you can t rely on being able  to manage process groups -- like when writing scripts for testing a piece of software which must be built in multiple environments -- this tree-walking technique is definitely helpful

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ps -o pid  --ppid  PPID   xargs kill -9

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I can t comment  not enough reputation   so I am forced to add a new answer  even though this is not really an answer   There is a slight problem with the otherwise very nice and thorough answer given by  olibre on Feb 28   The output of ps opgid   PID will contain leading spaces for a PID shorter than five digits because ps is justifying the column  rigth align the numbers    Within the entire command line  this results in a negative sign  followed by space s   followed by the group PID   Simple solution is to pipe ps to tr to remove spaces   kill -- -   ps opgid   PID   tr -d

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This is my version of killing all the child processes using bash script  It does not use recursion and depends on pgrep command   Use   killtree sh PID SIGNAL   Contents of killtrees sh     bin bash PID  1 if   -z  PID    then     echo  No pid specified  fi  PPLIST  PID CHILD LIST  pgrep -P  PPLIST -d    while     -z   CHILD LIST    do     PPLIST   PPLIST  CHILD LIST      CHILD LIST  pgrep -P  CHILD LIST -d   done  SIGNAL  2  if   -z  SIGNAL   then     SIGNAL  TERM  fi  do substring from comma to space kill - SIGNAL   PPLIST

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And now for some clever shell programming   There is a cost with this solution  but at least it is based on everyday iteration and recursion  This can be converted to bash by paying careful attention to the typeset commands and converting them to declare or local where appropriate   Discussion  When killing a process  one must deal with the realty that it could be a parent to many children  and that each child could be the parent of even more children  and on  and on  an on   What to do   If only there was a function to test if a process had children  and another function to return the child PIDs of a parent process   Then  the game would be much simpler  because you could create a loop to iterate over a list of PIDs  checking each one for children before killing it  If there are no children  just kill the process  If there are children  call the driving function recursively and pass it the results of a function that gets the PIDs of a parent s children   The base case action  process does not have children       bin ksh  function killProcess          typeset -r PID  1      if      isProcess  PID        then         echo -e  Process  PID cannot be terminated because it does not exist  n  1 gt  amp 2         return 1     elif    kill -s TERM  PID     amp  amp       isProcess  PID        then         echo -e  Process  PID was terminated  n  1 gt  amp 2         return 0     elif kill -s KILL  PID         echo -e  Process  PID killed with SIGKILL  9  signal  No time to clean up potential files  n  1 gt  amp 2         return 0     elif isZombie  PID     then         echo -e  Process  PID in the zombie status  n  1 gt  amp 2          return 2     else         echo -e  Process  PID is alive  SIGTERM and SIGKILL had no effect  It is not a zombie  n  1 gt  amp 2     fi      return 3    function attemptToKillPid          typeset -r PID  1      if killProcess  PID     then          return 0     fi      ppid   getParentPid  pid      echo -e  Process  pid of parent  ppid was not able to be killed  n  1 gt  amp 2     return 1     The general case action  process has children    function killPidFamily          typeset -r PROCESSES        typeset -ir NUM PROCESSES TO KILL   countLines  PROCESSES      typeset -i numKilledProcesses 0     typeset ppid      for pid in  PROCESSES     do         pid   trim  pid           if   hasChildPids  pid         then             attemptToKillPid  pid  amp  amp     numKilledProcesses              else             killPidFamily   getChildPids  pid   amp  amp  attemptToKillPid  pid  amp  amp     numKilledProcesses              fi     done         numKilledProcesses    NUM PROCESSES TO KILL        return        Library of supporting functions      bin ksh  function trim          echo -n   1    tr -d   space      function countLines          typeset -r  LIST        trim   echo  LIST   wc -l   awk   print  1       function getProcesses            NOTE  -o pgid below would be  4 in awk       ps -e -o comm pid ppid pgid user ruid euid group rgid egid etime etimes stat --no-headers    function getProcess         typeset -r PID  1    ps -p  PID -o comm pid ppid pgid user ruid euid group rgid egid etime etimes stat --no-headers    function isProcess          typeset -r PID  1      ps -p  PID -o pid --no-headers 1 gt  amp 2     return       function getProcessStatus          typeset -r PID  1     trim   ps -p  PID -o stat --no-headers     function isZombie          typeset -r PID  1     typeset processStatus      processStatus   getProcessStatus  PID            processStatus      Z         return       function hasChildPids          typeset -r PPID  1     echo   getProcesses    awk   print  3     sort -n   uniq   grep     PPID        return       function getChildPids          typeset -r PPID  1     echo   getProcesses    awk   print  2   3     sort -k 2   awk    2     PPID  print   1     sort -n    function getParentPid          typeset -r PID  1     trim   echo   getProcess  PID    awk   print  3        In this way  you know for sure that the process tree is being destroyed from the branches  moving up to the root  This helps avoid the potential of creating zombies and other undesirable situations   Now  that you have seen the most expensive way to do this  killing one process at a time   investigate how you could alter this solution to use the PGID  process group ID   The getProcesses    function already prints the PGID   4 in awk   so learn how to use it  or don t

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pkill -TERM -P 27888   This will kill all processes that have the parent process ID 27888   Or more robust   CPIDS   pgrep -P 27888    sleep 33  amp  amp  kill -KILL  CPIDS  amp    kill -TERM  CPIDS   which schedule killing 33 second later and politely ask processes to terminate   See this answer for terminating all descendants

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Old question  I know  but all the responses seem to keep calling ps  which I didn t like   This awk-based solution doesn t require recursion and only calls ps once   awk  BEGIN     p 1390   while   ps -o ppid pid  getline  a  1  a  1     2   o 1   while  o  1        o 0     split p  q           for  i in q  if  a q i                p p  a q i         o 1       a q i                  system  kill -TERM  p       Or on a single-line   awk  BEGIN  p 1390 while   ps -o ppid pid  getline  a  1  a  1     2 o 1 while  o  1   o 0 split p  q       for  i in q   if  a q i         p p  a q i   o 1 a q i        system  kill -TERM  p      Basically the idea is that we build up an array  a  of parent child entries  then loop around the array finding children for our matching parents  adding them to our parents list  p  as we go   If you don t want to kill the top-level process  then doing  sub   0-9         p    just before the system   line would remove it from the kill set   Bear in mind that there is a race condition here  but that s true  as far as I can see  of all of the solutions  It does what I needed because the script I needed it for doesn t create lots of short-lived children   An exercise for the reader would be to make it a 2-pass loop  after the first pass  send SIGSTOP to all processes in the p list  then loop to run ps again and after the second pass send SIGTERM  then SIGCONT  If you don t care about nice endings then second-pass could just be SIGKILL  I suppose

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You don t say if the tree you want to kill is a single process group    This is often the case if the tree is the result of forking from a server start or a shell command line    You can discover process groups using GNU ps as follows    ps x -o    p  r  y  x  c     If it is a process group you want to kill  just use the kill 1  command but instead of giving it a process number  give it the negation of the group number   For example to kill every process in group 5112  use kill -TERM -- -5112

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The following shell function is similar to many of the other answers  but it works both on Linux and BSD  OS X  etc  without external dependencies like pgrep   killtree         local parent  1 child     for child in   ps -o ppid  -o pid    awk    1   parent  print   2     do         killtree  child     done     kill  parent

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Inspired by ysth   s comment  kill -- -PGID      instead of giving it a process number  give it the negation of the group   number  As usual with almost any command  if you want a normal argument that   starts with a - to not be interpreted as a switch  precede it with --

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I know that is old  but that is the better solution that i found   killtree          for p in   pstree -p  1   grep -o      digit        grep -o     digit        tac  do         echo Terminating   p          kill  p     done

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rkill command from pslist package sends given signal  or SIGTERM by default  to specified process and all its descendants   rkill  -SIG  pid name

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You don t say if the tree you want to kill is a single process group    This is often the case if the tree is the result of forking from a server start or a shell command line    You can discover process groups using GNU ps as follows    ps x -o    p  r  y  x  c     If it is a process group you want to kill  just use the kill 1  command but instead of giving it a process number  give it the negation of the group number   For example to kill every process in group 5112  use kill -TERM -- -5112

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brad s answer is what I d recommend too  except that you can do away with awk altogether if you use the --ppid option to ps   for child in   ps -o pid -ax --ppid  PPID  do         done

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I know that is old  but that is the better solution that i found   killtree          for p in   pstree -p  1   grep -o      digit        grep -o     digit        tac  do         echo Terminating   p          kill  p     done

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In sh the jobs command will list the background processes  In some cases it might be better to kill the newest process first  e g  the older one created a shared socket  In those cases sort the PIDs in reverse order  Sometimes you want to wait moment for the jobs to write something on disk or stuff like that before they stop   And don t kill if you don t have to   for SIGNAL in TERM KILL  do   for CHILD in   jobs -s sort -r   do     kill -s  SIGNAL  CHILD     sleep  MOMENT   done done

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if you have pstree and perl on your system  you can try this   perl -e  kill 9    pstree -p PID     m     d     sg

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Kill The Group Using Only Name of Process Which Belongs to Group  kill -- -  ps -ae o pid pgrp cmd   grep  quot  e xample py quot    awk   print  2     tail -1   This is a modification of olibre s answer but you don t need to know the PID  just the name of a member of the group  Explanation  To get the group id you do the ps command using the arguments as shown  grep it for your command  but formatting example py with quotes and using the bracket for the first letter  this filters out the grep command itself  then filter it through awk to get the second field which is the group id  The tail -1 gets rid of duplicate group ids  You put all of that in a variable using the     syntax and voila     you get the group id  So you substitute that   mess  for that -groupid above

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brad s answer is what I d recommend too  except that you can do away with awk altogether if you use the --ppid option to ps   for child in   ps -o pid -ax --ppid  PPID  do         done

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If you want to kill a process by name   killall -9 -g someprocessname   or  pgrep someprocessname   xargs pkill -9 -g

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The following shell function is similar to many of the other answers  but it works both on Linux and BSD  OS X  etc  without external dependencies like pgrep   killtree         local parent  1 child     for child in   ps -o ppid  -o pid    awk    1   parent  print   2     do         killtree  child     done     kill  parent

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If you want to kill a process by name   killall -9 -g someprocessname   or  pgrep someprocessname   xargs pkill -9 -g

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In sh the jobs command will list the background processes  In some cases it might be better to kill the newest process first  e g  the older one created a shared socket  In those cases sort the PIDs in reverse order  Sometimes you want to wait moment for the jobs to write something on disk or stuff like that before they stop   And don t kill if you don t have to   for SIGNAL in TERM KILL  do   for CHILD in   jobs -s sort -r   do     kill -s  SIGNAL  CHILD     sleep  MOMENT   done done

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This script also work     bin sh while true do   echo  Enter parent process id   type quit for exit     read ppid   if    ppid -eq  quit  -o  ppid -eq  QUIT    then      exit 0   fi   for i in  ps -ef  awk   3      ppid    print  2          do        echo killing  i        kill  i      done done

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Kill The Group Using Only Name of Process Which Belongs to Group  kill -- -  ps -ae o pid pgrp cmd   grep  quot  e xample py quot    awk   print  2     tail -1   This is a modification of olibre s answer but you don t need to know the PID  just the name of a member of the group  Explanation  To get the group id you do the ps command using the arguments as shown  grep it for your command  but formatting example py with quotes and using the bracket for the first letter  this filters out the grep command itself  then filter it through awk to get the second field which is the group id  The tail -1 gets rid of duplicate group ids  You put all of that in a variable using the     syntax and voila     you get the group id  So you substitute that   mess  for that -groupid above

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Here is a variation of  zhigang s answer which does without AWK  relying only on Bash s native parsing possibilities   function killtree     kill -STOP   1    ps -e -o pid  -o ppid    while read -r pid ppid                            do                                  ppid    1       continue                              killtree   pid      true   Skip over failures                            done   kill -CONT   1              kill -TERM   1      It seems to work fine on both Macs and Linux  In situations where you can t rely on being able  to manage process groups -- like when writing scripts for testing a piece of software which must be built in multiple environments -- this tree-walking technique is definitely helpful

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The following has been tested on FreeBSD  Linux and MacOS X and only depends on pgrep and kill  the ps -o versions don t work under BSD   First argument is parent pid of which children have to be terminated  second argument is a boolean to determine whether the parent pid has to be terminated too   KillChilds             local pid    1           local self    2 -false            if children    pgrep -P   pid     then                 for child in  children  do                         KillChilds   child  true                 done         fi          if     self     true    then                 kill -s SIGTERM   pid      sleep 10  amp  amp  kill -9   pid   amp           fi    KillChilds     gt   dev null 2 gt  amp 1   This will send SIGTERM to any child   grandchild process within a shell script and if SIGTERM doesn t succeed  it will wait 10 seconds and then send kill     Earlier answer   The following also works but will kill the shell itself on BSD   KillSubTree         local parent    1       for child in   ps -o pid  parent   do             if      -ne  child    then  kill -s SIGTERM  child     sleep 10  amp  amp  kill -9  child  amp      gt   dev null 2 gt  amp 1   fi     done     Example lanch from within script KillSubTree     gt   dev null 2 gt  amp 1

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This is my version of killing all the child processes using bash script  It does not use recursion and depends on pgrep command   Use   killtree sh PID SIGNAL   Contents of killtrees sh     bin bash PID  1 if   -z  PID    then     echo  No pid specified  fi  PPLIST  PID CHILD LIST  pgrep -P  PPLIST -d    while     -z   CHILD LIST    do     PPLIST   PPLIST  CHILD LIST      CHILD LIST  pgrep -P  CHILD LIST -d   done  SIGNAL  2  if   -z  SIGNAL   then     SIGNAL  TERM  fi  do substring from comma to space kill - SIGNAL   PPLIST

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It s super easy to do this with python using psutil  Just install psutil with pip and then you have a full suite of process manipulation tools   def killChildren pid       parent   psutil Process pid      for child in parent get children True           if child is running                child terminate

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If you know the pid of the thing you want to kill  you can usually go from the session id  and everything in the same session  I d double check  but I used this for scripts starting rsyncs in loops that I want to die  and not start another  because of the loop  as it would if I d just killall d rsync   kill   ps -o pid  -s   ps -o sess --no-heading --pid 21709     If you don t know the pid you can still nest more  kill   ps -o pid  -s   ps -o sess --no-heading --pid   pgrep rsync

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To kill a process tree recursively  use killtree        bin bash  killtree         local  pid  1     local  sig   2 --TERM      kill -stop    pid    needed to stop quickly forking parent from producing children between child killing and parent killing     for  child in   ps -o pid --no-headers --ppid    pid    do         killtree    child     sig      done     kill -   sig     pid     if      -eq 0 -o    -gt 2    then     echo  Usage    basename  0   lt pid gt   signal       exit 1 fi  killtree

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if you have pstree and perl on your system  you can try this   perl -e  kill 9    pstree -p PID     m     d     sg

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Thanks for your wisdom  folks  My script was leaving some child processes on exit and the negation tip made things easier  I wrote this function to be used in other scripts if necessary     kill my group s subprocesses           killGroup   kill also myself                       killGroup -x   kill another group s subprocesses      killGroup N     kill that group all                    killGroup -x N   N  PID of the main process    process group ID    function killGroup          local prid mainpid     case  1 in         -x    -n   2     amp  amp  kill -9 - 2    kill -9 -                  mainpid                   mainpid  1        esac     prid   ps ax -o pid pgid   grep  mainpid      prid   prid   mainpid       kill -9  prid 2 gt  dev null     return     Cheers

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Thanks for your wisdom  folks  My script was leaving some child processes on exit and the negation tip made things easier  I wrote this function to be used in other scripts if necessary     kill my group s subprocesses           killGroup   kill also myself                       killGroup -x   kill another group s subprocesses      killGroup N     kill that group all                    killGroup -x N   N  PID of the main process    process group ID    function killGroup          local prid mainpid     case  1 in         -x    -n   2     amp  amp  kill -9 - 2    kill -9 -                  mainpid                   mainpid  1        esac     prid   ps ax -o pid pgid   grep  mainpid      prid   prid   mainpid       kill -9  prid 2 gt  dev null     return     Cheers

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You don t say if the tree you want to kill is a single process group    This is often the case if the tree is the result of forking from a server start or a shell command line    You can discover process groups using GNU ps as follows    ps x -o    p  r  y  x  c     If it is a process group you want to kill  just use the kill 1  command but instead of giving it a process number  give it the negation of the group number   For example to kill every process in group 5112  use kill -TERM -- -5112

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if you know pass the pid of the parent process  here s a shell script that should work   for child in   ps -o pid ppid -ax        awk    if     2     pid     print   1      do   echo  Killing child process  child because ppid    pid    kill  child done

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if you know pass the pid of the parent process  here s a shell script that should work   for child in   ps -o pid ppid -ax        awk    if     2     pid     print   1      do   echo  Killing child process  child because ppid    pid    kill  child done

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type ps -ef check the process id  Kill the process by typing kill -9  lt pid gt

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brad s answer is what I d recommend too  except that you can do away with awk altogether if you use the --ppid option to ps   for child in   ps -o pid -ax --ppid  PPID  do         done

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Kill all the processes belonging to the same process tree using the Process Group ID  PGID    kill -- - PGID  nbsp   nbsp  Use default signal  TERM   15  kill -9 - PGID  nbsp   nbsp  Use the signal KILL  9    You can retrieve the PGID from any Process-ID  PID  of the same process tree   kill -- -  ps -o pgid   PID   grep -o   0-9       nbsp   signal TERM  kill -9 -  ps -o pgid   PID   grep -o   0-9       nbsp   signal KILL    Special thanks to tanager and Speakus for contributions on  PID remaining spaces and OSX compatibility   Explanation   kill -9 -  PGID     Send signal 9  KILL  to all child and grandchild    PGID   ps opgid    PID      Retrieve the Process-Group-ID from any Process-ID of the tree  not only the Process-Parent-ID  A variation of ps opgid   PID is ps -o pgid --no-headers  PID where pgid can be replaced by pgrp   But    ps inserts leading spaces when PID is less than five digits and right aligned as noticed by tanager  You can use  PGID   ps opgid    PID    tr -d       ps from OSX always print the header  therefore Speakus proposes  PGID     ps -o pgid   PID    grep  0-9    tr -d          grep -o  0-9   prints successive digits only  does not print spaces or alphabetical headers     Further command lines  PGID   ps -o pgid   PID   grep -o  0-9    kill -TERM -  PGID     kill -15 kill -INT  -  PGID     correspond to  CRTL C  from keyboard kill -QUIT -  PGID     correspond to  CRTL    from keyboard kill -CONT -  PGID     restart a stopped process  above signals do not kill it  sleep 2                wait terminate process  more time if required  kill -KILL -  PGID     kill -9 if it does not intercept signals  or buggy    Limitation   As noticed by davide and Hubert Kario  when kill is invoked by a process belonging to the same tree  kill risks to kill itself before terminating the whole tree killing  Therefore  be sure to run the command using a process having a different Process-Group-ID      Long story   gt  cat run-many-processes sh    bin sh echo  ProcessID    begins   0     child sh background  amp    child sh foreground echo  ProcessID    ends   0     gt  cat child sh    bin sh echo  ProcessID    begins   0     grandchild sh background  amp    grandchild sh foreground echo  ProcessID    ends   0     gt  cat grandchild sh    bin sh echo  ProcessID    begins   0   sleep 9999 echo  ProcessID    ends   0     Run the process tree in background using   amp     gt    run-many-processes sh  amp      ProcessID 28957 begins    run-many-processes sh  ProcessID 28959 begins    child sh  ProcessID 28958 begins    child sh  ProcessID 28960 begins    grandchild sh  ProcessID 28961 begins    grandchild sh  ProcessID 28962 begins    grandchild sh  ProcessID 28963 begins    grandchild sh    gt  PID                         get the Parent Process ID  gt  PGID   ps opgid    PID      get the Process Group ID   gt  ps fj  PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND 28348 28349 28349 28349 pts 3    28969 Ss   33021   0 00 -bash 28349 28957 28957 28349 pts 3    28969 S    33021   0 00      bin sh   run-many-processes sh 28957 28958 28957 28349 pts 3    28969 S    33021   0 00          bin sh   child sh background 28958 28961 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh background 28961 28965 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28958 28963 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh foreground 28963 28967 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28957 28959 28957 28349 pts 3    28969 S    33021   0 00          bin sh   child sh foreground 28959 28960 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh background 28960 28964 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28959 28962 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh foreground 28962 28966 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28349 28969 28969 28349 pts 3    28969 R    33021   0 00     ps fj   The command pkill -P  PID does not kill the grandchild    gt  pkill -P   PID    run-many-processes sh  line 4  28958 Terminated                child sh background   run-many-processes sh  line 4  28959 Terminated                child sh foreground ProcessID 28957 ends    run-many-processes sh   1    Done                      run-many-processes sh   gt  ps fj  PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND 28348 28349 28349 28349 pts 3    28987 Ss   33021   0 00 -bash 28349 28987 28987 28349 pts 3    28987 R    33021   0 00     ps fj     1 28963 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh foreground 28963 28967 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999     1 28962 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh foreground 28962 28966 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999     1 28961 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh background 28961 28965 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999     1 28960 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh background 28960 28964 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999   The command kill -- - PGID kills all processes including the grandchild    gt  kill --    -  PGID     default signal is TERM  kill -15   gt  kill -CONT -  PGID     awake stopped processes  gt  kill -KILL -  PGID     kill -9 to be sure   gt  ps fj  PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND 28348 28349 28349 28349 pts 3    29039 Ss   33021   0 00 -bash 28349 29039 29039 28349 pts 3    29039 R    33021   0 00     ps fj   Conclusion  I notice in this example PID and PGID are equal  28957    This is why I originally thought kill -- - PID was enough  But in the case the process is spawn within a Makefile the Process ID is different from the Group ID    I think kill -- -  ps -o pgid   PID   grep -o  0-9    is the best simple trick to kill a whole process tree when called from a different Group ID  another process tree

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It is probably better to kill the parent before the children  otherwise the parent may likely spawn new children again before he is killed himself  These will survive the killing   My version of ps is different from that above  maybe too old  therefore the strange grepping     To use a shell script instead of a shell function has many advantages     However  it is basically zhigangs idea       bin bash if test    -lt 1   then     echo  gt  amp 2  usage  kiltree pid  sig   fi     pid  1  sig   2 -TERM   children   ps j   grep          pid      cut -c 7-11    echo  gt  amp 2 kill -   sig     pid  kill -   sig     pid  for  child in    children   do     killtree    child     sig  done

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Modified version of zhigang s answer      usr bin env bash set -eu  killtree         local pid     for pid  do         kill -stop  pid         local cpid         for cpid in   pgrep -P  pid   do             killtree  cpid         done         kill  pid         kill -cont  pid         wait  pid 2 gt  dev null    true    done    cpids         local pid  1 options   2 -  space   3 -      local cpid     for cpid in   pgrep -P  pid   do         echo   space cpid          if       options a         options      then             cpids  cpid   options    space            fi     done    while true  do sleep 1  done  amp  cpid    for i in   seq 1 2   do     cpids    a     sleep 1 done killtree  cpid echo --- cpids    a

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I develop the solution of zhigang  xyuri and solidsneck further       bin bash  if test    -lt 1   then     echo  gt  amp 2  usage  kiltree pid  sig       exit 1     fi     pid  1  sig   2 -TERM     echo  gt  amp 2  killtree   pid  mypid         ps axwwf   grep -6         pid    gt  amp 2    function  killtree          local  children     local  child     local  success      if test  1 -eq  2   then   this is killtree - don t commit suicide          echo  gt  amp 2  killtree can  t kill it  s own branch - some processes will survive              return 1         fi         this avoids that children are spawned or disappear      kill -SIGSTOP  2         children   ps -o pid --no-headers --ppid  2                 success 0      for  child in    children   do          killtree  1    child   3            success      success              done        if test   success -eq 0   then         kill - 3  2       fi         when a stopped process is killed  it will linger in the system until it is continued     kill -SIGCONT  2     test   success -eq 0       return            killtree      pid   sig   This version will avoid killing its ancestry - which causes a flood of child processes in the previous solutions   Processes are properly stopped before the child list is determined  so that no new children are created or disappear   After being killed  the stopped jobs have to be continued to disappear from the system

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rkill command from pslist package sends given signal  or SIGTERM by default  to specified process and all its descendants   rkill  -SIG  pid name

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You don t say if the tree you want to kill is a single process group    This is often the case if the tree is the result of forking from a server start or a shell command line    You can discover process groups using GNU ps as follows    ps x -o    p  r  y  x  c     If it is a process group you want to kill  just use the kill 1  command but instead of giving it a process number  give it the negation of the group number   For example to kill every process in group 5112  use kill -TERM -- -5112

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pkill -TERM -P 27888   This will kill all processes that have the parent process ID 27888   Or more robust   CPIDS   pgrep -P 27888    sleep 33  amp  amp  kill -KILL  CPIDS  amp    kill -TERM  CPIDS   which schedule killing 33 second later and politely ask processes to terminate   See this answer for terminating all descendants

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To add to Norman Ramsey s answer  it may be worth looking at at setsid if you want to create a process group  http   pubs opengroup org onlinepubs 009695399 functions setsid html     The setsid   function shall create a   new session  if the calling process is   not a process group leader  Upon   return the calling process shall be   the session leader of this new   session  shall be the process group   leader of a new process group  and   shall have no controlling terminal    The process group ID of the calling   process shall be set equal to the   process ID of the calling process  The   calling process shall be the only   process in the new process group and   the only process in the new session    Which I take to mean that you can create a group from the starting process   I used this in php in order to be able to kill a whole process tree after starting it     This may be a bad idea   I d be interested in comments

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Old question  I know  but all the responses seem to keep calling ps  which I didn t like   This awk-based solution doesn t require recursion and only calls ps once   awk  BEGIN     p 1390   while   ps -o ppid pid  getline  a  1  a  1     2   o 1   while  o  1        o 0     split p  q           for  i in q  if  a q i                p p  a q i         o 1       a q i                  system  kill -TERM  p       Or on a single-line   awk  BEGIN  p 1390 while   ps -o ppid pid  getline  a  1  a  1     2 o 1 while  o  1   o 0 split p  q       for  i in q   if  a q i         p p  a q i   o 1 a q i        system  kill -TERM  p      Basically the idea is that we build up an array  a  of parent child entries  then loop around the array finding children for our matching parents  adding them to our parents list  p  as we go   If you don t want to kill the top-level process  then doing  sub   0-9         p    just before the system   line would remove it from the kill set   Bear in mind that there is a race condition here  but that s true  as far as I can see  of all of the solutions  It does what I needed because the script I needed it for doesn t create lots of short-lived children   An exercise for the reader would be to make it a 2-pass loop  after the first pass  send SIGSTOP to all processes in the p list  then loop to run ps again and after the second pass send SIGTERM  then SIGCONT  If you don t care about nice endings then second-pass could just be SIGKILL  I suppose

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Thanks for your wisdom  folks  My script was leaving some child processes on exit and the negation tip made things easier  I wrote this function to be used in other scripts if necessary     kill my group s subprocesses           killGroup   kill also myself                       killGroup -x   kill another group s subprocesses      killGroup N     kill that group all                    killGroup -x N   N  PID of the main process    process group ID    function killGroup          local prid mainpid     case  1 in         -x    -n   2     amp  amp  kill -9 - 2    kill -9 -                  mainpid                   mainpid  1        esac     prid   ps ax -o pid pgid   grep  mainpid      prid   prid   mainpid       kill -9  prid 2 gt  dev null     return     Cheers

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Modified version of zhigang s answer      usr bin env bash set -eu  killtree         local pid     for pid  do         kill -stop  pid         local cpid         for cpid in   pgrep -P  pid   do             killtree  cpid         done         kill  pid         kill -cont  pid         wait  pid 2 gt  dev null    true    done    cpids         local pid  1 options   2 -  space   3 -      local cpid     for cpid in   pgrep -P  pid   do         echo   space cpid          if       options a         options      then             cpids  cpid   options    space            fi     done    while true  do sleep 1  done  amp  cpid    for i in   seq 1 2   do     cpids    a     sleep 1 done killtree  cpid echo --- cpids    a

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Kill all the processes belonging to the same process tree using the Process Group ID  PGID    kill -- - PGID  nbsp   nbsp  Use default signal  TERM   15  kill -9 - PGID  nbsp   nbsp  Use the signal KILL  9    You can retrieve the PGID from any Process-ID  PID  of the same process tree   kill -- -  ps -o pgid   PID   grep -o   0-9       nbsp   signal TERM  kill -9 -  ps -o pgid   PID   grep -o   0-9       nbsp   signal KILL    Special thanks to tanager and Speakus for contributions on  PID remaining spaces and OSX compatibility   Explanation   kill -9 -  PGID     Send signal 9  KILL  to all child and grandchild    PGID   ps opgid    PID      Retrieve the Process-Group-ID from any Process-ID of the tree  not only the Process-Parent-ID  A variation of ps opgid   PID is ps -o pgid --no-headers  PID where pgid can be replaced by pgrp   But    ps inserts leading spaces when PID is less than five digits and right aligned as noticed by tanager  You can use  PGID   ps opgid    PID    tr -d       ps from OSX always print the header  therefore Speakus proposes  PGID     ps -o pgid   PID    grep  0-9    tr -d          grep -o  0-9   prints successive digits only  does not print spaces or alphabetical headers     Further command lines  PGID   ps -o pgid   PID   grep -o  0-9    kill -TERM -  PGID     kill -15 kill -INT  -  PGID     correspond to  CRTL C  from keyboard kill -QUIT -  PGID     correspond to  CRTL    from keyboard kill -CONT -  PGID     restart a stopped process  above signals do not kill it  sleep 2                wait terminate process  more time if required  kill -KILL -  PGID     kill -9 if it does not intercept signals  or buggy    Limitation   As noticed by davide and Hubert Kario  when kill is invoked by a process belonging to the same tree  kill risks to kill itself before terminating the whole tree killing  Therefore  be sure to run the command using a process having a different Process-Group-ID      Long story   gt  cat run-many-processes sh    bin sh echo  ProcessID    begins   0     child sh background  amp    child sh foreground echo  ProcessID    ends   0     gt  cat child sh    bin sh echo  ProcessID    begins   0     grandchild sh background  amp    grandchild sh foreground echo  ProcessID    ends   0     gt  cat grandchild sh    bin sh echo  ProcessID    begins   0   sleep 9999 echo  ProcessID    ends   0     Run the process tree in background using   amp     gt    run-many-processes sh  amp      ProcessID 28957 begins    run-many-processes sh  ProcessID 28959 begins    child sh  ProcessID 28958 begins    child sh  ProcessID 28960 begins    grandchild sh  ProcessID 28961 begins    grandchild sh  ProcessID 28962 begins    grandchild sh  ProcessID 28963 begins    grandchild sh    gt  PID                         get the Parent Process ID  gt  PGID   ps opgid    PID      get the Process Group ID   gt  ps fj  PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND 28348 28349 28349 28349 pts 3    28969 Ss   33021   0 00 -bash 28349 28957 28957 28349 pts 3    28969 S    33021   0 00      bin sh   run-many-processes sh 28957 28958 28957 28349 pts 3    28969 S    33021   0 00          bin sh   child sh background 28958 28961 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh background 28961 28965 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28958 28963 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh foreground 28963 28967 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28957 28959 28957 28349 pts 3    28969 S    33021   0 00          bin sh   child sh foreground 28959 28960 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh background 28960 28964 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28959 28962 28957 28349 pts 3    28969 S    33021   0 00              bin sh   grandchild sh foreground 28962 28966 28957 28349 pts 3    28969 S    33021   0 00                 sleep 9999 28349 28969 28969 28349 pts 3    28969 R    33021   0 00     ps fj   The command pkill -P  PID does not kill the grandchild    gt  pkill -P   PID    run-many-processes sh  line 4  28958 Terminated                child sh background   run-many-processes sh  line 4  28959 Terminated                child sh foreground ProcessID 28957 ends    run-many-processes sh   1    Done                      run-many-processes sh   gt  ps fj  PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND 28348 28349 28349 28349 pts 3    28987 Ss   33021   0 00 -bash 28349 28987 28987 28349 pts 3    28987 R    33021   0 00     ps fj     1 28963 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh foreground 28963 28967 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999     1 28962 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh foreground 28962 28966 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999     1 28961 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh background 28961 28965 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999     1 28960 28957 28349 pts 3    28987 S    33021   0 00  bin sh   grandchild sh background 28960 28964 28957 28349 pts 3    28987 S    33021   0 00     sleep 9999   The command kill -- - PGID kills all processes including the grandchild    gt  kill --    -  PGID     default signal is TERM  kill -15   gt  kill -CONT -  PGID     awake stopped processes  gt  kill -KILL -  PGID     kill -9 to be sure   gt  ps fj  PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND 28348 28349 28349 28349 pts 3    29039 Ss   33021   0 00 -bash 28349 29039 29039 28349 pts 3    29039 R    33021   0 00     ps fj   Conclusion  I notice in this example PID and PGID are equal  28957    This is why I originally thought kill -- - PID was enough  But in the case the process is spawn within a Makefile the Process ID is different from the Group ID    I think kill -- -  ps -o pgid   PID   grep -o  0-9    is the best simple trick to kill a whole process tree when called from a different Group ID  another process tree

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The following has been tested on FreeBSD  Linux and MacOS X and only depends on pgrep and kill  the ps -o versions don t work under BSD   First argument is parent pid of which children have to be terminated  second argument is a boolean to determine whether the parent pid has to be terminated too   KillChilds             local pid    1           local self    2 -false            if children    pgrep -P   pid     then                 for child in  children  do                         KillChilds   child  true                 done         fi          if     self     true    then                 kill -s SIGTERM   pid      sleep 10  amp  amp  kill -9   pid   amp           fi    KillChilds     gt   dev null 2 gt  amp 1   This will send SIGTERM to any child   grandchild process within a shell script and if SIGTERM doesn t succeed  it will wait 10 seconds and then send kill     Earlier answer   The following also works but will kill the shell itself on BSD   KillSubTree         local parent    1       for child in   ps -o pid  parent   do             if      -ne  child    then  kill -s SIGTERM  child     sleep 10  amp  amp  kill -9  child  amp      gt   dev null 2 gt  amp 1   fi     done     Example lanch from within script KillSubTree     gt   dev null 2 gt  amp 1

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ps -o pid  --ppid  PPID   xargs kill -9

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I use a little bit modified version of a method described here  https   stackoverflow com a 5311362 563175  So it looks like that   kill  pstree -p 24901   sed  s    n  g    grep       sed  s             1     tr   n         where 24901 is parent s PID   It looks pretty ugly but does it s job perfectly

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Thanks for your wisdom  folks  My script was leaving some child processes on exit and the negation tip made things easier  I wrote this function to be used in other scripts if necessary     kill my group s subprocesses           killGroup   kill also myself                       killGroup -x   kill another group s subprocesses      killGroup N     kill that group all                    killGroup -x N   N  PID of the main process    process group ID    function killGroup          local prid mainpid     case  1 in         -x    -n   2     amp  amp  kill -9 - 2    kill -9 -                  mainpid                   mainpid  1        esac     prid   ps ax -o pid pgid   grep  mainpid      prid   prid   mainpid       kill -9  prid 2 gt  dev null     return     Cheers

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This script also work     bin sh while true do   echo  Enter parent process id   type quit for exit     read ppid   if    ppid -eq  quit  -o  ppid -eq  QUIT    then      exit 0   fi   for i in  ps -ef  awk   3      ppid    print  2          do        echo killing  i        kill  i      done done

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It s super easy to do this with python using psutil  Just install psutil with pip and then you have a full suite of process manipulation tools   def killChildren pid       parent   psutil Process pid      for child in parent get children True           if child is running                child terminate

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Killing child process in shell script   Many time we need to kill child process which are hanged or block for some reason  eg  FTP connection issue   There are two approaches   1  To create separate new parent for each child which will monitor and kill child process once timeout reached   Create test sh as follows      bin bash  declare -a CMDs   AAA   BBB   CCC   DDD   for CMD in   CMDs      do      sleep 10  amp  PID     echo  Started  CMD   gt   PID   sleep 5  echo  Killing  CMD   gt   PID   kill  PID  echo   CMD Completed     amp  done exit    and watch processes which are having name as  test  in other terminal using following command   watch -n1  ps x -o   p  r  c    grep  test      Above script will create 4 new child processes and their parents  Each child process will run for 10sec  But once timeout of 5sec reach  thier respective parent processes will kill those childs  So child won t be able to complete execution 10sec    Play around those timings switch 10 and 5  to see another behaviour  In that case child will finish execution in 5sec before it reaches timeout of 10sec   2  Let the current parent monitor and kill child process once timeout reached  This won t create separate parent to monitor each child  Also you can manage all child processes properly within same parent   Create test sh as follows      bin bash  declare -A CPIDs  declare -a CMDs   AAA   BBB   CCC   DDD    CMD TIME 15  for CMD in   CMDs      do      echo  Started   CMD   sleep  CMD TIME  echo   CMD Done     amp      CPIDs       RN       sleep 1  done  GPID   ps -o pgid       CNT TIME OUT 10  CNT 0  while  true   do     declare -A TMP CPIDs       for PID in     CPIDs       do         echo  Checking    CPIDs  PID     gt   PID           if ps -p  PID  gt   dev null   then           echo  -- gt    CPIDs  PID     gt   PID  is running               TMP CPIDs  PID    CPIDs  PID            else           echo  -- gt    CPIDs  PID     gt   PID  is completed            fi     done      if      TMP CPIDs        0    then         echo  All commands completed            break      else         unset CPIDs          declare -A CPIDs          for PID in     TMP CPIDs       do             CPIDs  PID    TMP CPIDs  PID            done         unset TMP CPIDs           if    CNT -gt  CNT TIME OUT    then             echo   CPIDs     PIDs not reponding  Timeout reached  CNT sec  killing all childern with GPID  GPID                 kill -- - GPID          fi     fi      CNT    CNT 1        echo  waiting since  b secs         sleep 1  done  exit    and watch processes which are having name as  test  in other terminal using following command   watch -n1  ps x -o   p  r  c    grep  test      Above script will create 4 new child processes  We are storing pids of all child process and looping over them to check if they are finished their execution or still running  Child process will execution till CMD TIME time  But if CNT TIME OUT timeout reach   All children will get killed by parent process  You can switch timing and play around with script to see behavior  One drawback of this approach is   it is using group id for killing all child tree  But parent process itself belong to same group so it will also get killed   You may need to assign other group id to parent process if you don   t want parent to be killed   More details can be found here   Killing child process in shell script

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And now for some clever shell programming   There is a cost with this solution  but at least it is based on everyday iteration and recursion  This can be converted to bash by paying careful attention to the typeset commands and converting them to declare or local where appropriate   Discussion  When killing a process  one must deal with the realty that it could be a parent to many children  and that each child could be the parent of even more children  and on  and on  an on   What to do   If only there was a function to test if a process had children  and another function to return the child PIDs of a parent process   Then  the game would be much simpler  because you could create a loop to iterate over a list of PIDs  checking each one for children before killing it  If there are no children  just kill the process  If there are children  call the driving function recursively and pass it the results of a function that gets the PIDs of a parent s children   The base case action  process does not have children       bin ksh  function killProcess          typeset -r PID  1      if      isProcess  PID        then         echo -e  Process  PID cannot be terminated because it does not exist  n  1 gt  amp 2         return 1     elif    kill -s TERM  PID     amp  amp       isProcess  PID        then         echo -e  Process  PID was terminated  n  1 gt  amp 2         return 0     elif kill -s KILL  PID         echo -e  Process  PID killed with SIGKILL  9  signal  No time to clean up potential files  n  1 gt  amp 2         return 0     elif isZombie  PID     then         echo -e  Process  PID in the zombie status  n  1 gt  amp 2          return 2     else         echo -e  Process  PID is alive  SIGTERM and SIGKILL had no effect  It is not a zombie  n  1 gt  amp 2     fi      return 3    function attemptToKillPid          typeset -r PID  1      if killProcess  PID     then          return 0     fi      ppid   getParentPid  pid      echo -e  Process  pid of parent  ppid was not able to be killed  n  1 gt  amp 2     return 1     The general case action  process has children    function killPidFamily          typeset -r PROCESSES        typeset -ir NUM PROCESSES TO KILL   countLines  PROCESSES      typeset -i numKilledProcesses 0     typeset ppid      for pid in  PROCESSES     do         pid   trim  pid           if   hasChildPids  pid         then             attemptToKillPid  pid  amp  amp     numKilledProcesses              else             killPidFamily   getChildPids  pid   amp  amp  attemptToKillPid  pid  amp  amp     numKilledProcesses              fi     done         numKilledProcesses    NUM PROCESSES TO KILL        return        Library of supporting functions      bin ksh  function trim          echo -n   1    tr -d   space      function countLines          typeset -r  LIST        trim   echo  LIST   wc -l   awk   print  1       function getProcesses            NOTE  -o pgid below would be  4 in awk       ps -e -o comm pid ppid pgid user ruid euid group rgid egid etime etimes stat --no-headers    function getProcess         typeset -r PID  1    ps -p  PID -o comm pid ppid pgid user ruid euid group rgid egid etime etimes stat --no-headers    function isProcess          typeset -r PID  1      ps -p  PID -o pid --no-headers 1 gt  amp 2     return       function getProcessStatus          typeset -r PID  1     trim   ps -p  PID -o stat --no-headers     function isZombie          typeset -r PID  1     typeset processStatus      processStatus   getProcessStatus  PID            processStatus      Z         return       function hasChildPids          typeset -r PPID  1     echo   getProcesses    awk   print  3     sort -n   uniq   grep     PPID        return       function getChildPids          typeset -r PPID  1     echo   getProcesses    awk   print  2   3     sort -k 2   awk    2     PPID  print   1     sort -n    function getParentPid          typeset -r PID  1     trim   echo   getProcess  PID    awk   print  3        In this way  you know for sure that the process tree is being destroyed from the branches  moving up to the root  This helps avoid the potential of creating zombies and other undesirable situations   Now  that you have seen the most expensive way to do this  killing one process at a time   investigate how you could alter this solution to use the PGID  process group ID   The getProcesses    function already prints the PGID   4 in awk   so learn how to use it  or don t

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type ps -ef check the process id  Kill the process by typing kill -9  lt pid gt

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To kill a process tree recursively  use killtree        bin bash  killtree         local  pid  1     local  sig   2 --TERM      kill -stop    pid    needed to stop quickly forking parent from producing children between child killing and parent killing     for  child in   ps -o pid --no-headers --ppid    pid    do         killtree    child     sig      done     kill -   sig     pid     if      -eq 0 -o    -gt 2    then     echo  Usage    basename  0   lt pid gt   signal       exit 1 fi  killtree

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Based on zhigang s answer  this avoids self-killing   init killtree         local pid  1 child      for child in   pgrep -P  pid   do         init killtree  child     done        pid -ne       amp  amp  kill -kill  pid

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I use a little bit modified version of a method described here  https   stackoverflow com a 5311362 563175  So it looks like that   kill  pstree -p 24901   sed  s    n  g    grep       sed  s             1     tr   n         where 24901 is parent s PID   It looks pretty ugly but does it s job perfectly

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if you know pass the pid of the parent process  here s a shell script that should work   for child in   ps -o pid ppid -ax        awk    if     2     pid     print   1      do   echo  Killing child process  child because ppid    pid    kill  child done

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Killing child process in shell script   Many time we need to kill child process which are hanged or block for some reason  eg  FTP connection issue   There are two approaches   1  To create separate new parent for each child which will monitor and kill child process once timeout reached   Create test sh as follows      bin bash  declare -a CMDs   AAA   BBB   CCC   DDD   for CMD in   CMDs      do      sleep 10  amp  PID     echo  Started  CMD   gt   PID   sleep 5  echo  Killing  CMD   gt   PID   kill  PID  echo   CMD Completed     amp  done exit    and watch processes which are having name as  test  in other terminal using following command   watch -n1  ps x -o   p  r  c    grep  test      Above script will create 4 new child processes and their parents  Each child process will run for 10sec  But once timeout of 5sec reach  thier respective parent processes will kill those childs  So child won t be able to complete execution 10sec    Play around those timings switch 10 and 5  to see another behaviour  In that case child will finish execution in 5sec before it reaches timeout of 10sec   2  Let the current parent monitor and kill child process once timeout reached  This won t create separate parent to monitor each child  Also you can manage all child processes properly within same parent   Create test sh as follows      bin bash  declare -A CPIDs  declare -a CMDs   AAA   BBB   CCC   DDD    CMD TIME 15  for CMD in   CMDs      do      echo  Started   CMD   sleep  CMD TIME  echo   CMD Done     amp      CPIDs       RN       sleep 1  done  GPID   ps -o pgid       CNT TIME OUT 10  CNT 0  while  true   do     declare -A TMP CPIDs       for PID in     CPIDs       do         echo  Checking    CPIDs  PID     gt   PID           if ps -p  PID  gt   dev null   then           echo  -- gt    CPIDs  PID     gt   PID  is running               TMP CPIDs  PID    CPIDs  PID            else           echo  -- gt    CPIDs  PID     gt   PID  is completed            fi     done      if      TMP CPIDs        0    then         echo  All commands completed            break      else         unset CPIDs          declare -A CPIDs          for PID in     TMP CPIDs       do             CPIDs  PID    TMP CPIDs  PID            done         unset TMP CPIDs           if    CNT -gt  CNT TIME OUT    then             echo   CPIDs     PIDs not reponding  Timeout reached  CNT sec  killing all childern with GPID  GPID                 kill -- - GPID          fi     fi      CNT    CNT 1        echo  waiting since  b secs         sleep 1  done  exit    and watch processes which are having name as  test  in other terminal using following command   watch -n1  ps x -o   p  r  c    grep  test      Above script will create 4 new child processes  We are storing pids of all child process and looping over them to check if they are finished their execution or still running  Child process will execution till CMD TIME time  But if CNT TIME OUT timeout reach   All children will get killed by parent process  You can switch timing and play around with script to see behavior  One drawback of this approach is   it is using group id for killing all child tree  But parent process itself belong to same group so it will also get killed   You may need to assign other group id to parent process if you don   t want parent to be killed   More details can be found here   Killing child process in shell script

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Based on zhigang s answer  this avoids self-killing   init killtree         local pid  1 child      for child in   pgrep -P  pid   do         init killtree  child     done        pid -ne       amp  amp  kill -kill  pid

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If you know the pid of the thing you want to kill  you can usually go from the session id  and everything in the same session  I d double check  but I used this for scripts starting rsyncs in loops that I want to die  and not start another  because of the loop  as it would if I d just killall d rsync   kill   ps -o pid  -s   ps -o sess --no-heading --pid 21709     If you don t know the pid you can still nest more  kill   ps -o pid  -s   ps -o sess --no-heading --pid   pgrep rsync

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if you know pass the pid of the parent process  here s a shell script that should work   for child in   ps -o pid ppid -ax        awk    if     2     pid     print   1      do   echo  Killing child process  child because ppid    pid    kill  child done

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I can t comment  not enough reputation   so I am forced to add a new answer  even though this is not really an answer   There is a slight problem with the otherwise very nice and thorough answer given by  olibre on Feb 28   The output of ps opgid   PID will contain leading spaces for a PID shorter than five digits because ps is justifying the column  rigth align the numbers    Within the entire command line  this results in a negative sign  followed by space s   followed by the group PID   Simple solution is to pipe ps to tr to remove spaces   kill -- -   ps opgid   PID   tr -d

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brad s answer is what I d recommend too  except that you can do away with awk altogether if you use the --ppid option to ps   for child in   ps -o pid -ax --ppid  PPID  do         done

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I develop the solution of zhigang  xyuri and solidsneck further       bin bash  if test    -lt 1   then     echo  gt  amp 2  usage  kiltree pid  sig       exit 1     fi     pid  1  sig   2 -TERM     echo  gt  amp 2  killtree   pid  mypid         ps axwwf   grep -6         pid    gt  amp 2    function  killtree          local  children     local  child     local  success      if test  1 -eq  2   then   this is killtree - don t commit suicide          echo  gt  amp 2  killtree can  t kill it  s own branch - some processes will survive              return 1         fi         this avoids that children are spawned or disappear      kill -SIGSTOP  2         children   ps -o pid --no-headers --ppid  2                 success 0      for  child in    children   do          killtree  1    child   3            success      success              done        if test   success -eq 0   then         kill - 3  2       fi         when a stopped process is killed  it will linger in the system until it is continued     kill -SIGCONT  2     test   success -eq 0       return            killtree      pid   sig   This version will avoid killing its ancestry - which causes a flood of child processes in the previous solutions   Processes are properly stopped before the child list is determined  so that no new children are created or disappear   After being killed  the stopped jobs have to be continued to disappear from the system

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To add to Norman Ramsey s answer  it may be worth looking at at setsid if you want to create a process group  http   pubs opengroup org onlinepubs 009695399 functions setsid html     The setsid   function shall create a   new session  if the calling process is   not a process group leader  Upon   return the calling process shall be   the session leader of this new   session  shall be the process group   leader of a new process group  and   shall have no controlling terminal    The process group ID of the calling   process shall be set equal to the   process ID of the calling process  The   calling process shall be the only   process in the new process group and   the only process in the new session    Which I take to mean that you can create a group from the starting process   I used this in php in order to be able to kill a whole process tree after starting it     This may be a bad idea   I d be interested in comments

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It is probably better to kill the parent before the children  otherwise the parent may likely spawn new children again before he is killed himself  These will survive the killing   My version of ps is different from that above  maybe too old  therefore the strange grepping     To use a shell script instead of a shell function has many advantages     However  it is basically zhigangs idea       bin bash if test    -lt 1   then     echo  gt  amp 2  usage  kiltree pid  sig   fi     pid  1  sig   2 -TERM   children   ps j   grep          pid      cut -c 7-11    echo  gt  amp 2 kill -   sig     pid  kill -   sig     pid  for  child in    children   do     killtree    child     sig  done

[linux] What's the best way to send a signal to all members of a process group?

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