Feb 8th, 2010
/etc/inittab parent of all processes
Init is the parent of all processes. Its primary role is to create processes from a script stored in the file /etc/inittab.
Some Linux implementations contain a table of processes to start automatically on bootup. On Linux systems this table is usually located in the special file /etc/inittab.
The Linux operating system uses an init system that utilizes run levels. A run level can be used to
direct the init process to run only certain types of processes, as defined in the /etc/inittab file. There are five init run levels in the Linux operating system.
At run level 1, only the basic system processes are started, along with one console terminal process. This is called single user mode. Single user mode is most often used for emergency filesystem maintenance when something is broken. Obviously, in this mode only one person (usually the
administrator) can log in to the system to manipulate data.
# of runlevel.
#
# Runlevel 0 is halt.
# Runlevel 1 is single-user.
# Runlevels 2-5 are multi-user.
# Runlevel 6 is reboot.
