Kill a process started with popen


After opening a pipe to a process with popen, is there a way to kill the process that has been started? (Using pclose is not what I want because that will wait for the process to finish, but I need to kill it.)

Best Answer

Don't use popen(), write your own wrapper that does what you'd like.

It's fairly straightforward to fork(), and then replace stdin & stdout by using dup2(), and then calling exec() on your child.

That way, your parent will have the exact child PID, and you can use kill() on that.

Google search for "popen2() implementation" for some sample code on how to implement what popen() is doing. It's only a dozen or so lines long. Taken from we can see an example that looks like this:

#define READ 0
#define WRITE 1

popen2(const char *command, int *infp, int *outfp)
    int p_stdin[2], p_stdout[2];
    pid_t pid;

    if (pipe(p_stdin) != 0 || pipe(p_stdout) != 0)
        return -1;

    pid = fork();

    if (pid < 0)
        return pid;
    else if (pid == 0)
        dup2(p_stdin[READ], READ);
        dup2(p_stdout[WRITE], WRITE);

        execl("/bin/sh", "sh", "-c", command, NULL);

    if (infp == NULL)
        *infp = p_stdin[WRITE];

    if (outfp == NULL)
        *outfp = p_stdout[READ];

    return pid;

NB: Seems like popen2() is what you want, but my distribution doesn't seem to come with this method.