Question

How can my program detect how it was started: by someone using the command-line or by another process?

The program has an optional interactive part that I want to suppress when it was started by another process – running in the background; but when it was started from a terminal I want it to do the interactive bit.

[edit] If it is possible to do from a C++ program.

Answer 1

Check if your stdin isatty, eg

if (isatty(0))
{
    /* interactive! */
}