Linux operating System (i)

1. Kernel-and system call (Shell, command).

Programming languages--assembly language->cpu Execution (algorithm is used to reduce CPU execution)

2.Linux Boot order: http://www.cnblogs.com/zhaodedong/p/5365148.html

Linux boot process (with picture): http://www.linuxidc.com/Linux/2014-03/97862.htm

Rc.local from the start, the resources are fully allocated after implementation;

3. User management: User group, user rights (User A can view User B's own files through the audit log, if you do disaster tolerant processing, it can be restored)

The administrator user has the same permissions as the root user, and the root user can delete the administrator user, but the administrator user does not have the remove root user right

Users within the same user group have the same administrative rights

4. Command:

Useradd (user, user ID, user group, Administrator user) |userdel|usermod|password|newgrp (Switch user group)

Groupadd|groupdel|groupmod

5. User-related system files

/etc/password User name (where you can find the user, ' * ' indicates that the user is being seized)

/etc/shadow User Password (modify uid=0, gid=0 can change it to an admin user?) ）

/etc/shadow the next 9 fields represent the meaning of the respective: http://www.cnblogs.com/zhousir1991/archive/2011/07/25/2116520.html

/etc/group

/dev/Device root directory

HDD (normal disk, media media is magnetic powder, according to North and South Pole to record), SSD (solid-state disk, media media is silicon wafer, because of the elimination of seek time, it is more efficient than HDD)

6. File System (tree-like structure)

LBC (Logical block Address)

File Call-VFS (virture file sys)-specific filesystem-block device-Kernel-disk

Device Type: Character device (one word, one word read and write), block device (read and write in blocks), network device

Linux operating System (i)