Programmatically check if a process is being run in the background

Question

2 questions:

1) Is there any Linux/Posix API to know if a process has been invoked as a background process?

linux> myprogram &

Answer 1

To answer your second part, that's usually called a daemon and they're built something like this.

main()
    pid = fork()
    if pid is child
          run program
    else we are the parent process
       exit to command prompt