cis-lclient06:~/class/nov22>more one.c
#include <stdio.h>
#include <stdlib.h>
main() {
    printf("This is program one\n");
    close(1);
    exit(0);
}
cis-lclient06:~/class/nov22>gcc -o one one.c
cis-lclient06:~/class/nov22>more exec3.c
#include <syscall.h>
#include <unistd.h>
#include <stdio.h>
int main(void) {
    execl("one", (char *) NULL);
    printf("Only get here if execl() fails\n");
}
cis-lclient06:~/class/nov22>gcc exec3.c
cis-lclient06:~/class/nov22>./a.out
This is program one
cis-lclient06:~/class/nov22>man 3 execv

NAME
       execl, execlp, execle, execv, execvp - execute a file

SYNOPSIS
       #include <unistd.h>

       extern char **environ;

       int execl(const char *path, const char *arg, ...);
       int execlp(const char *file, const char *arg, ...);
       int execle(const char *path, const char *arg,
                  ..., char * const envp[]);
       int execv(const char *path, char *const argv[]);
       int execvp(const char *file, char *const argv[]);

DESCRIPTION
       The exec() family of functions replaces the current process image with a new process image.
       The functions described in this manual page are front-ends for execve(2).  (See the  manual
       page for execve(2) for further details about the replacement of the current process image.)
...
q
cis-lclient06:~/class/nov22>man 2 execve
NAME
       execve - execute program

SYNOPSIS
       #include <unistd.h>

       int execve(const char *filename, char *const argv[],
                  char *const envp[]);

DESCRIPTION
       execve()  executes  the  program  pointed to by filename.  filename must be either a binary
       executable, or a script starting with a line of the form:

           #! interpreter [optional-arg]

       For details of the latter case, see "Interpreter scripts" below.
...
q
cis-lclient06:~/class/nov22>