How to kill a child process by the parent process

Question

I create a child process using a fork    How can the parent process kill the child process if the child process cannot complete its execution within 30 seconds  I want to allow the child process to execute up to 30 seconds  If it takes more than 30 seconds  the parent process will kill it  Do you have any idea to do that

User · Answer

Send a SIGTERM or a SIGKILL to it   http   en wikipedia org wiki SIGKILL  http   en wikipedia org wiki SIGTERM  SIGTERM is polite and lets the process clean up before it goes  whereas  SIGKILL is for when it won t listen      Example from the shell  man page  http   unixhelp ed ac uk CGI man-cgi kill       kill -9 pid   In C  you can do the same thing using the kill syscall   kill pid  SIGKILL     See the following man page  http   linux die net man 2 kill

User · Answer

Try something like this    include  lt signal h gt   pid t child pid   -1     Global  void kill child int sig        kill child pid SIGKILL      int main int argc  char  argv          signal SIGALRM  void     int  kill child       child pid   fork        if  child pid  gt  0           PARENT           alarm 30                         Do parent s tasks here                      wait NULL             else if  child pid    0          CHILD                         Do child s tasks here

User · Answer

In the parent process  fork   s return value is the process ID of the child process  Stuff that value away somewhere for when you need to terminate the child process  fork   returns zero 0  in the child process   When you need to terminate the child process  use the kill 2  function with the process ID returned by fork    and the signal you wish to deliver  e g  SIGTERM    Remember to call wait   on the child process to prevent any lingering zombies

[c] How to kill a child process by the parent process?

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