/etc/inittab,/etc/init.d/rcs and/etc/profile Analysis

After kernel mount the root file system, the first program to run is the LINUXRC under the root directory, which is actually a link to/bin/busybox, which means that the first program to run after the system is busybox itself.

BusyBox first resolves the/etc/inittab configuration file, which reads as follows:

# Boot-time System configuration/initialization script.
:: Sysinit:/etc/init.d/rcs			(RcS is a script that initializes the configuration and is executed first) # Example of how to put

a Getty on a serial line (for a terminal)
:: Respawn:/sbin/getty-l ttyS000 115200 VT100- n root-i "Auto login as Root ..."   (setting console properties) # Stuff to does when

restarting the init process
:: restart:/sbin/in It

# Stuff to do before rebooting
:: Ctrlaltdel:/sbin/reboot
:: Shutdown:/bin/umount-a-R
:: Shutdown :/sbin/swapoff-a

When you enter the console command line, the/etc/profile file is executed automatically, with the following contents:

Set environment variables (such as PATH, Ld_library_path),

Set Umask 0222 (the default permission for the created file is 644),

Set the color of the note and print "Welcom to Linux"

In short, execute/etc/inittab first, then call/etc/init.d/rcs, and finally execute/etc/profile