Unix basic tutorial 1 system composition
1. Portability
2. Multi-user and multi-task time-sharing system
3. Software reuse
4. Input / output operation independent of the device
5. The interface is convenient and efficient
6. the security mechanism is perfect.
7. Multilingual support
8. Network and resource sharing
9. System tools (commands) and system services
User-shell--- resident module-kernel-hardware
System tools: command
Startup process
Boot--OS kernel-hardware check-install rootfs-- to form process 0-generate child process-parent process: swap process swap--- child process: generate process 1 init-- execute inittab-- initialization each port-getty-- login-execute command-exit
