Is it possible for a single thread to control multiple processes simultaneously?

In the classical understanding, a single thread (thread) is a unit of execution within a process, and process management is usually handled at the operating system level, not by individual threads. However, one thread can indirectly manage multiple processes, for example, through system calls, creating and controlling several child processes (fork/exec in Unix systems).

That is, a thread can launch and interact with multiple processes, for example, through descriptors, signals, or IPC (inter-process communication). But a thread itself does not "manage" processes in a direct sense; this is done by the OS.

Example in C (Unix):

#include <unistd.h>
#include <sys/wait.h>
#include <stdio.h>

int main() {
    pid_t pid1 = fork();
    if (pid1 == 0) {
        // Child process 1
        execlp("ls", "ls", NULL);
    }

    pid_t pid2 = fork();
    if (pid2 == 0) {
        // Child process 2
        execlp("date", "date", NULL);
    }

    // Parent thread waits for child processes to finish
    waitpid(pid1, NULL, 0);
    waitpid(pid2, NULL, 0);

    printf("Both processes are finished\n");
    return 0;
}

Here, one thread (the main thread) creates and manages two processes.