I've finished my project about Linux socket using select(), fork(), and pthread.
There are some recommended and useful resources:
1. Programming in C UNIX System Calls and Subroutines using C
It introduces socket, pthread, fork, and RPC(Remote Procedure Call).
2. SAS/C Library Reference: Socket Function Reference
It provides varied functions, such as select(), htons(), send()...,etc.
3. Programming IP Socket on Linux, Part One
It introduces how to write socket on Linux platform.
4. Linux Kernel Hacker's Guide
It provides the methods about how to write your embedded system components, such as device driver.
5. Socket Program Design (Socket程式設計)
It provides details of writing socket ( in Traditional-Chinese language)