9.1. The Interactive C Shell
Before the C shell displays a prompt, it is preceded by a number of processes. See Figure 9.1.
Figure 9.1. System startup and the C shell.
9.1.1. Startup
After the system boots, the first process to run is called init; it is assigned process identification number (PID) 1. It gets instructions from a file called inittab (System V) or spawns a getty process (BSD). These processes are responsible for opening up the terminal ports, for providing a place where input comes from (stdin), where standard output (stdout) and error (stderr) go, and for putting a login prompt on your screen. The /bin/login program is then executed. ...
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