System Initialization and Recovery
Starting the processes and having a system file recovery
During startup, the Linux OS performs various low-level tasks such as memory system initialization, device driver-hardware device loading and interfacing, filesystem mounting and so on. Importantly, the init process - the parent of all executing processes is also created. The init process' primary responsibility is starting up the processes and services specified in /etc/inittab. Typically, these services include gettys (virtual terminals that allow user login), and scripts in the directory /etc/rc that usually spawn high-level daemons like the web server, database server etc. The /var/log/messages file normally contains startup log messages.
If the machine was turned off without shutting down properly, a system utility e2fsck or fsck is automatically executed to repair it. It is a good idea to also execute this command manually on each filesystem:
# e2fsck /dev/hda2
The umount command should be used to unmount a file system before checking or repairing the file system. Files recovered during the fsck process go into the lost+found directory. The latest versions of most distributions offer automatic filesystem recovery using event logs.
