Linux命令帮助

1、命令一般格式

COMMAND  [ OPTION ]  ARGUMENT

2、常见命令

[ifconfig](http://blog.51cto.com/2857034/2161663)

3、查询命令是否为内置命令

> type COMMAND

  >type find

find is /usr/bin/find

>type cd

  cd is a shell builtin

>type echo

echo is a shell builtin

4、查询命令帮助

内置命令：

help  COMMAND

> help echo

外置命令：

COMMAND --help

>find --help

info信息页：

>info echo

>info find

man手册页：

默认搜索路径：/usr/share/man ，有9个section组成

  各section作用：

1  Executable programs or shell commands

2  System calls (functions provided by the kernel)

3  Library calls (functions within program libraries)

4  Special files (usually found in /dev)

5  File formats and conventions eg /etc/passwd

6  Games

7  Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7)

8  System administration commands (usually only for root)

9  Kernel routines [Non standard]

实例：

1、查询COMMAND手册页section位置

>whatis find

find (1)            - search for files in a directory hierarchy

>whatis echo

echo (1)            - display a line of text

2、查询对应手册页帮助

man  [section]  COMMAND

man  1  find

man  1  echo