System Behavior ()

Question

I use the system () call to run tail -f.

One thing that I saw is that calling the tail takes 2 processes (I see in ps): 1) sh -c tail filename 2) the name of the tail file

As the man page says: system () executes the command specified in the command by invoking the / bin / sh -c command. I think process 1) is inevitable, right?

I'm just wondering if I can reduce the number of processes from 2 to 1.

Thanks in advance.

Answer 1

System

always executes the sh -c command. If you want only one process, run the system command ("exec tail -f").

Answer 2

fork()/exec() . system() , , .

/* Untested code, but you get the idea */
switch ((pid = fork())) {
case -1:
    perror("fork");
    break;
case 0:
    execl("/usr/bin/tail", "tail", "-f", filename);
    perror("execl");
    exit(1);
default:
    wait(pid);
    ...
}