Update 20160826 Understanding Different Classifications of Shell Commands and Their Usage in Linux.md

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@ -16,23 +16,25 @@ Different classifications of Linux commands fall under the following classificat
### 1. 程序可执行文件(文件系统命令)
When you run a command, Linux searches through the directories stored in the $PATH environmental variable from left to right for the executable of that specific command.
当你执行一条命令的时候Linux 通过从左到右搜索存储在 $PATH 环境变量中的目录来找到这条命令的可执行文件。
You can view the directories in the $PATH as follows:
你可以像下面这样查看存储在 $PATH 中的目录
```
$ echo $PATH
/home/aaronkilik/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
```
In the above order, the directory /home/aaronkilik/bin will be searched first followed by /usr/local/sbin and so on, the order is significant in the search process.
在上面的命令中,目录 /home/aaronkilik/bin 将会被首先搜索,紧跟着是 /usr/local/sbin然后一直接着下去。在搜索进程中搜索顺序是至关重要的。
Examples of file system commands in /usr/bin directory:
比如在 /usr/bin 目录中的文件系统命令:
```
$ ll /bin/
```
Sample Output
样本输出
```
total 16284
@ -64,8 +66,10 @@ lrwxrwxrwx 1 root root 6 Jul 31 16:19 bzfgrep -> bzgrep*
```
### 2. Linux Aliases
### 2. Linux 的别名
These are user defined commands, they are created using the alias shell built-in command, and contain other shell commands with some options and arguments. The ideas is to basically use new and short names for lengthy commands.
这些是命令是用户定义的,
The syntax for creating an alias is as follows: