Linux Self-study note (4): Instructions for getting help from Linux

Source: Internet
Author: User

Access to Linux command help

External command: There is an executable program, located in the file system directory;

Echo (COMMAND)

Internal command:

Help COMMAND

External command help:
(1) Help manual

COMMAND--help
                 # COMMAND -h(2)使用手册(manual)                 # man COMMAND(3)信息页                 # info COMMAND(4)程序自身的帮助文档                 README                 INSTALL                 ChangeLog(5)程序官方文档                 官方网站:Documentation

Internal command help:

Help COMMAND
hash命令:    shell搜寻到的外部命令的路径结果会缓存至kv(key-value)存储中:

History command

管理命令历史    登录shell时,会读取命令历史文件中记录下的命令:~/.bash_history    登录进shell后新执行的命令只会记录在缓存中:这些命令会在用户退出时“追加”只命令历史文件中    history: history [-c] [-d 偏移量] [n] 或 history -anrw [文件名] 或 history -ps 参数 [参数...]显示或操纵历史列表。带行号显示历史列表,将每个被修改的条目加上前缀 参数 N 会仅列出最后的 N 个条目。选项:  -c    删除所有条目从而清空历史列表。  -d 偏移量    从指定位置删除历史列表。  -a    将当前绘画的历史行追加到历史文件中  -n    从历史文件中读取所有未被读取的行  -r    读取历史文件并将内容追加到历史列表中    中  -w    将当前历史写入到历史文件中    并追加到历史列表中  -p    对每一个 ARG 参数展开历史并显示结果    而不存储到历史列表中  -s    以单条记录追加 ARG 到历史列表中如果给定了 FILENAME 文件名,则它将被作为历史文件。否则如果 $HISTFILE 变量有值的话使用之,不然使用 ~/.bash_history 文件。如果 $HISTTIMEFORMAT 变量被设定并且不为空,它的值会被用于strftime(3) 的格式字符串来打印与每一个显示的历史条目想关联的时间戳,否则不打印时间戳。

External commands help get:
(2) Man COMMAND
Manual page:/usr/share/man/
Man1......man8
Man1: User Commands
Man2: System call
MAN3:C Library Call
MAN4: Equipment files and special files
MAN5: Configuration file format
Man6: Games
Note: Some correlations exist in more than one Zhang Jie moderator's manual:
To view the manuals in the development chapters: Man # COMMAND

Configuration file for man command:/etc/man.config
Manoath/path/to/somewhere: Indicates the new manual file search location

Man-m/path/to/somewhere: Set up the position under the Search Command command of the hand album and display it;

The paragraph description in the Help manual:
Synopsis
[]: Optional content
<>: Required Content
A|b: Two Choose one
... : The same content can appear multiple times

How to operate the man command:
Space: Want to flip the file tail screen
B: Want to file the first flip screen
Q: Exit

1 g: Back to File header
G: Turn to the tail of the file

Text Search:
/
Want to file from the current location love your tail search, not case-sensitive;
N: Next
N: Previous

(3) Info
Info COMMAND
(4) Help documentation for the program itself
/usr/share/doc/command-version
(5) Official documents
(6) Official version of the release document
Www.redhat.com\docs
(7) Slideshare.net

Linux Self-study note (4): Instructions for getting help from Linux

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