Detailed Linux-command information

Command (command) information detailed

This article address: http://blog.csdn.net/caroline_wendy/article/details/22663081

Test environment: Ubuntu 12.04 + GNOME Terminal 3.4 .1.1

In Linux, there are four main commands: executable program, shell builtin (shell), shell function (function), alias command (alias);

type: displays the type of the command; format: type command

which: displays the location of the executable; format: which command ; can only display functions, built-in commands are empty (ubuntu);

help: Display help article; Format: help command ; Note: When help cd, vertical bar ("