Which Linux system functions are responsible for starting and creating new processes?

In Linux, the system calls used to create and launch new processes are:

• fork() — creates a new process that is a copy of the calling process. The new process is called a child.
• exec() (for example, execl(), execvp(), and other variants) — replaces the current process with a new executable.

A typical scenario for launching a new process looks like this:

1. The process calls fork(), creating a copy of itself.
2. In the child process, exec() is called to load and run a new program.

Example in C:

pid_t pid = fork();
if (pid == 0) {
    // Child process
    execl("/bin/ls", "ls", "-l", (char *)NULL);
    // If exec returns, an error occurred
    perror("execl");
    exit(1);
} else if (pid > 0) {
    // Parent process
    wait(NULL); // Wait for the child to finish
} else {
    // fork error
    perror("fork");
}

Thus, fork() and exec() are key system functions for creating and launching new processes in Linux.