BusyBox has a minimal init program that uses a configuration file, /etc/inittab, to define rules to start programs at boot up and to stop them at shutdown. Usually, the actual work is done by shell scripts, which, by convention, are placed in the /etc/init.d directory.
init begins by reading /etc/inittab. This contains a list of programs to run, one per line, with this format:
<id>::<action>:<program>
The role of these parameter is as follows:
- id: This is the controlling Terminal for the command
- action: This is the conditions to run this command, as shown in the following paragraph
- program: This is the program to run
The actions are as follows:
- sysinit: Runs the program when init starts before any of the other types of actions.
- respawn: Runs the program and restarts it if it terminates. It is typically used to run a program as a daemon.
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