Question

Okay, so I have a problem. I must get the output of a program using the execlp and make the output go directly to a file. The problem is that the program only outputs certain information if it’s running in a tty,(I guess it calls isatty(3)).
Here is my code so far

void main(){
    int fd = open("file", O_WRONLY | O_CREAT | O_TRUNC, 0755);
    close(1);
    dup(fd);
    execlp("program","program",NULL);
    close(fd);
}

I don’t want to use OS commands like script (which works) or so on.

So the question is, how can I “trick” the program into thinking that it is writing into a tty?

Answer 1

Use a "pty" (Pseudo Terminal) as output. see this question for details.

Rachid Koucha wrote a lengthy article explaining the details how to work with ptys: Using pseudo-terminals (pty) to control interactive programs

Stop reading This text here just exists to stop the stupid SO algorithm to turn my answer into a comment. I hate it when software makes itself smarter than me 🙁