Comparison between SystemVinit startup and Busyboxinit startup

Generally speaking, there are two different initialization methods for Linux/Unix systems. 1) BSDsysteminit2) most of the distribution kits of SystemVinit use the init, which is similar to SystemVinit, that is, SysVinit...
Generally, Linux/Unix systems have two different initialization methods. 1) BSD system init2) System V init most of the release kits of Linux use init, which is similar to System V init, namely Sys V init, it is easier and more flexible than the traditional BSD system init. The main idea of System V init is to define different runlevels )". you can use the/etc/inittab configuration file to define the running level during system boot and what to do when you enter or switch to a running level. each running level corresponds to a sub-directory/etc/rc. d/rc n. d. the following is a general System V init process: (1) the first script executed during the init process is/etc/rc. d/rc. sysinit is mainly used for initialization at various running levels, including starting swap partitions, checking disks, setting host names, checking and attaching file systems, and loading and initializing hardware modules. (2) the content of executing the default run-level mode is mainly reflected in/etc/inittab. the inittab file will tell the init process to enter the running level, and where to find the configuration file for this running level. (3) run/etc/rc. d/rc. the local script file is also the last script file executed during the init process. Therefore, you can add some commands to be executed before logon. (4) execute the/bin/login program www.2cto.com Busybox init startup process and analyze its init process to perform the following work: <*> set a signal processing process for the init process <*> initialize the console <*> parse/etc/inittab <*> by default, busybox will run the initialization script/etc/init. d/RC after the init process initializes the console, Busybox will check whether the/etc/inittab file exists. If yes, it will parse the file and execute the corresponding running level. busybox supports the following inittab formats: id: runlevel: action: process note that the/etc/inittab format recognized by Busybox is very similar to Sys V init, however, the operation domain id has different meanings. the id in Busybox is used to specify the console to be started. if the started process is not an interactive Shell, you do not need to enter an operation domain with an id empty. [note] no matter whether Busybox can find the inittab file, the first script executed by init in Busybox is/etc/init. d/rcS, instead of the script file executed under the Sys V init structure/etc/rc. d/rc. sysinit. author: haohetao