Get PID of running firefox process

Question

How can get I get the PID of the "firefox" process in C?

In this code, system only returns 0, indicating success. How can I get the PID?

int x = system("pidof -s firefox");
printf("%d\n", x);

Use [`popen`](http://linux.die.net/man/3/popen) instead of `system`. — kaylum, Apr 26 '16 at 20:53
I've reworded your question to make it easier to read; but I'm just a person like you, so if you disagree, you can change it back. — user253751, Apr 26 '16 at 20:54
The `system()` command returns a value related to the given command's exit status. You want the command's *output*. — John Bollinger, Apr 26 '16 at 20:54

score 1 · Answer 1 · edited Apr 27 '16 at 00:49

popen is what you want: it opens a process and output from the open process is available to read just like a file stream opened with fopen:

FILE *f = popen("pgrep firefox", "r");
if (NULL == f)
{
    perror("popen");
}
else
{   
    char buffer[128];
    while (fgets(buffer, sizeof buffer, f))
    {
         // do something with read line
         int pid;
         sscanf(buffer, "%d", &pid)
    }
    // close the process
    pclose(f);
}

See man popen

Get PID of running firefox process

1 Answers1