如何终止该做的exec运行的其他程序一个子进程 [英] How to terminate a child process which is running another program by doing exec
问题描述
我在做我的主程序叉，并在子进程，这将运行另一个程序做的exec。现在我想终止子（即，由EXEC调用的程序）并返回到主程序（或父程序）。我怎么能做到这一点。我用Ctrl + C，但其杀死父进程和子试图also.please帮助我。
I'm doing fork in my main program,and doing exec in the child process which will run another program. Now i want to terminate the child(i.e., the program invoked by exec) and return back to the main program(or parent program). how could i achieve this.. I tried with ctrl+c but its killing parent process and child also.please help me.
/*This is main.c*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
#include <sys/wait.h>
void sig_int(void);
void sig_term(void);
pid_t pid,ppid;
int main(char argc,char **argv){
int n;
char ch;
printf("***********Application to start or stop services**********\n");
do
{
printf("Enter 1 to start service no.1\n");
printf("Enter 2 to start service no.2\n");
printf("Enter 3 to start service no.3\n");
scanf("%d",&n);
if(fork() == 0)
{
switch(n)
{
case 1: printf("starting service no. 1..\n");
printf("checking whether the given service is already running...\n");
// system("./det.sh ./test")
pid = getpid();
printf("child process pid = %d\n",pid);
// signal(SIGINT,(void *)sig_int);
// signal(SIGTERM,(void *)sig_term);
//execl("/var/vR_main","vR_main",argv[1],argv[2],argv[3],argv[4],NULL);
execl("./test","test",0,0);//will run test.c
break;
case 2: printf("starting service no. 2..\n");
break;
case 3: printf("starting service no. 3..\n");
break;
}
}
else
{
int status;
wait(&status);
if (WIFEXITED(status))
printf("CHILD exited with %d\n", WEXITSTATUS(status));
if (WIFSIGNALED(status))
printf("signaled by %d\n", WTERMSIG(status));
if (WIFSTOPPED(status))
printf("stopped by %d\n", WSTOPSIG(status));
// sleep(2);
ppid = getpid();
printf("%d\n",ppid);
// wait();
printf("\nDo you want to continue...y/n:");
scanf(" %c",&ch);
}
}while(ch == 'y');
return 0;
}
void sig_int(void)
{
printf("caught signal\n");
kill(pid,SIGKILL);
// signal(SIGINT,SIG_DFL);
// exit(0);
}
void sig_term(void)
{
printf("killing the process\n");
signal(SIGINT,SIG_DFL);
// exit(0);
}
/*This is test.c*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
void sig_int(void);
void sig_term(void);
pid_t pid;
int main()
{
// int a=10,b=40,c=50,max;
pid = getpid();
printf("exec pid = %d\n",pid);
while (1)
{
signal(SIGINT,(void *)sig_int);
signal(SIGTERM,(void *)sig_term);
}
// max=a>b?a>c?a:c:b>c?b:c;
// printf("%d\n",max);
}
void sig_int(void)
{
printf("caught signal\n");
// signal(SIGINT,SIG_DFL);
kill(pid,SIGKILL);
// exit(0);
}
void sig_term(void)
{
printf("killing the process\n");
signal(SIGINT,SIG_DFL);
// exit(0);
}
现在我想要杀测试应用程序（由EXEC调用），并返回到父进程或else块，以继续执行程序。
Now I want to kill "test application" (invoked by exec),and return to the parent process or the "else block" to continue the program.
推荐答案
您需要做到以下几点：
- 请在
杀（PID，SIGTERM）第一 - 这使子进程一个机会，优雅地终止 - 等待一段时间（使用
睡眠）。的时间周期取决于子过程需要从容关闭的时间。 - 使用
waitpid函数（PID，和放大器;状态，WNOHANG）检查返回值。如果进程不会中止执行步骤4 - 请在
杀（PID，SIGKILL），然后通过执行收获僵尸waitpid函数（PID，和放大器;状态，0）。
- Do a
kill(pid, SIGTERM) first - this gives the child process an opportunity to terminate gracefully - Wait a period of time (use
sleep). The period of time depends on the time the child process takes to close down gracefully. - Use
waitpid(pid, &status, WNOHANG)checking the return value. If the process has not aborted do step 4 - Do a
kill(pid, SIGKILL) then harvest the zombie by doingwaitpid(pid, &status, 0).
这些步骤确保你给子进程有一个信号处理程序关闭，并确保你没有僵死进程。
These steps ensure that you give the child process to have a signal handler to close down and also ensures that you have no zombie processes.
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