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I am reading Tanenbaum's book at the moment on modern operating systems. He is taliking about system calls and he implies that when a command is entered into a shell on a POSIX system, the shell forks a new process. Is this true and if so why?
when you enter into a command in a UNIX shell the shell forks itself and then exec()'s the new program. IIRC this is the only way to start a brand new process on a POSIX system.