I have a shell, where I switch to another user with su -l anotheruser, this mostly works
But when there is no pty allocated to su, it errors out with:

su: must be run from a terminal

So, I tried to wrap su with code to create a pty:

#include <stdio.h>
#include <string.h>
#include <pty.h>
#include <unistd.h>

int main (int argc, char *argv[])
{
    int fd;
    char* args[] = {"/bin/su", "-l", "anotheruser", NULL };
    char name[16] = {0};
    int pid ;

    pid = forkpty(&fd, name, NULL, NULL);
    if (pid != -1) {
        printf("n pty: [%s]n", name);
        if (execve(args[0], args, NULL) == -1) {
            printf("n execve: failedn");
        }
    } else {
        printf("n forkpty: failed n");
    }

    return 0;
}

But this doesn’t seem to work..
I am missing something here, but not able to make out.. do I have to
redirect stdin/stdout before execve()?