Difference between revisions of "Boot process"
From Linuxintro
imported>ThorstenStaerk |
imported>ThorstenStaerk |
||
| Line 17: | Line 17: | ||
= the init script are executed = | = the init script are executed = | ||
| − | This can be SysV init scripts or upstart or systemd. These init scripts typically start services. Services are grouped into runlevels. Some notable services are: | + | This can be SysV init scripts or upstart or systemd. These init scripts typically start services. Services are grouped into runlevels. E.g. in SUSE the runlevels are defines as |
| + | * 0: reboot | ||
| + | * 1: rescue system, single user | ||
| + | * 2: all services that run in (1) plus services needed for multi-user login | ||
| + | * 3: all services that run in (2) plus network services | ||
| + | * 4: undefined | ||
| + | * 5: all services that run in (3) plus graphical display | ||
| + | Some notable services are: | ||
* alsasound | * alsasound | ||
: Used for the alsa sound system | : Used for the alsa sound system | ||
| Line 27: | Line 34: | ||
: Used for enlightenment sound system | : Used for enlightenment sound system | ||
* ntp | * ntp | ||
| + | : Network Time Protocol to keep your clock in sync with the real time via the network | ||
* autofs boot.udev xdm | * autofs boot.udev xdm | ||
* cifs xfs | * cifs xfs | ||
* cron ypbind | * cron ypbind | ||
* powerd | * powerd | ||
| − | * gpm network sshd | + | * gpm network |
| + | * sshd | ||
| + | : Service that allows to [[control a computer via the network]] | ||
= X Windowing system is started = | = X Windowing system is started = | ||
Revision as of 15:00, 11 January 2014
How Linux typically starts up on a PC
Contents
- 1 you switch on the computer
- 2 the master boot record is executed
- 3 the boot loader is executed
- 4 the Linux kernel is executed
- 5 the initrd is loaded/executed
- 6 the init program is started
- 7 the init script are executed
- 8 X Windowing system is started
- 9 login manager is started
- 10 user session incl. Desktop environment is started
- 11 See also
you switch on the computer
BIOS is shown and the devices are check
the master boot record is executed
the boot loader is executed
The boot loader is typically grub, and there is an older and smaller called lilo.
the Linux kernel is executed
the initrd is loaded/executed
the init program is started
The Linux kernel starts the init program. Nothing else. If the init process quits, the Linux kernel panics. Init is responsible for all further services and programs that are started.
the init script are executed
This can be SysV init scripts or upstart or systemd. These init scripts typically start services. Services are grouped into runlevels. E.g. in SUSE the runlevels are defines as
- 0: reboot
- 1: rescue system, single user
- 2: all services that run in (1) plus services needed for multi-user login
- 3: all services that run in (2) plus network services
- 4: undefined
- 5: all services that run in (3) plus graphical display
Some notable services are:
- alsasound
- Used for the alsa sound system
- cups
- Used for printing, it is the common Unix printing system
- dbus
- Used to call public functions in running programs. Should be abstracted to users.
- esound
- Used for enlightenment sound system
- ntp
- Network Time Protocol to keep your clock in sync with the real time via the network
- autofs boot.udev xdm
- cifs xfs
- cron ypbind
- powerd
- gpm network
- sshd
- Service that allows to control a computer via the network
