Boot Process in Debian / Ubuntu: Difference between revisions
Created page with "Boot up phases There are 4 phases to starting up the system: # BIOS # Boot loader # Kernel # Upstart (which manages system tasks and services ) Kernel modules ..." |
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Upstart is the initialization scripts that run. These scripts involve different /etc/rc scripts and upstart events. | Upstart is the initialization scripts that run. These scripts involve different /etc/rc scripts and upstart events. | ||
The old init system was replaced by the new "upstart" system. | |||
== init / runlevel == | |||
The runlevel 5 makes the sytem boot to the graphical xwindows, while the runlevel 3 boots to text console. | |||
To change the default runlevel, use your favorite text editor on /etc/init/rc-sysinit.conf | |||
vi /etc/init/rc-sysinit.conf | |||
To see the current (and previous) runlevel: | |||
runlevel | |||
To switch runlevels: | |||
init $runlevel | |||
To reboot | |||
init 6 | |||
To change the default runlevel, use your favorite text editor on /etc/init/rc-sysinit.conf... | |||
sudo vim /etc/init/rc-sysinit.conf | |||
Change this line to whichever runlevel you want... | |||
env DEFAULT_RUNLEVEL=5 | |||
Revision as of 15:09, 26 February 2017
Boot up phases
There are 4 phases to starting up the system:
- BIOS
- Boot loader
- Kernel
- Upstart (which manages system tasks and services )
Kernel modules are loaded during the Kernel phase. The kernel uses a file system which is present in memory, called an 'initrd' for 'initial ram disk'. The kernel launches the init script inside the initrd file system, which loads hardware drivers and finds the root partition.
Upstart is the initialization scripts that run. These scripts involve different /etc/rc scripts and upstart events.
The old init system was replaced by the new "upstart" system.
init / runlevel
The runlevel 5 makes the sytem boot to the graphical xwindows, while the runlevel 3 boots to text console.
To change the default runlevel, use your favorite text editor on /etc/init/rc-sysinit.conf
vi /etc/init/rc-sysinit.conf
To see the current (and previous) runlevel:
runlevel
To switch runlevels:
init $runlevel
To reboot
init 6
To change the default runlevel, use your favorite text editor on /etc/init/rc-sysinit.conf...
sudo vim /etc/init/rc-sysinit.conf
Change this line to whichever runlevel you want...
env DEFAULT_RUNLEVEL=5