Change boot mode in Linux

There are 6 boot modes.

0 –  Halt (Shutdown)
1 – Single user mode
2 – Not yet implemented
3 – Full multi-user command line mode
4 – Not used.
5 – Full multi-user Graphical User Interface mode
6 – Reboot

Default mode is written into /etc/inittab file.

By changing the following line in that file,  the default boot mode will be changed:

id:5:initdefault:

If it is production server and you don’t need to use GUI interface you can set default boot mode to 3. This is beneficial, because  the mode 3 takes less memory(RAM)  than the mode 5.

id:3:initdefault:

Note: Be careful while changing the default mode, because the following values like 0(shutdown) or 6(reboot) will cause problems. Never try to set these values, I mean 0 or 6.