Linux Basic Command Notes (iii)

Summarize some Linux commands for easy memory and learning

Common command format for Linux commands

command word [options] [parameters]

Example: ls-l/etc

Several auxiliary operations for command line editing

Tab key: Auto-completing

Backslash "\": Force line break

Shortcut key ctrl+u: Empty to the beginning of the line

Shortcut key ctrl+k: Empty to end of line

Shortcut key ctrl+l: Clear Screen

Shortcut keys CTRL + C: cancel this command edit

Help commands (you can see the relevant usage and description of the command)

Commands to be viewed by Help (internal command)

Example: Help pwd

Command--help (external command)

Example: LS--help

Man help manual command

Man needs to see the commands for example: Man ls

Export the man Help manual to a text document to learn

Man Command | Col-b > Ysf.txt

Pipe: with "|" Indicates that the previous command result is the input object of the following command

REDIRECT output: Use ">" to save the previous command result to the file specified later

Cat command

Purpose: Displays the contents of the file

More commands

Usage: Full screen mode to display the contents of the file (display percentage), press "Enter" key, a line down; Press SPACEBAR, PAGE DOWN; press the B key to page up; press the Q key to exit and return to the original command environment.

Less command

Purpose: The same as the more command, but the extension function more, press "up and down" arrow key to Line; Press PAGE up and PAGE down key to page; Press "/" key to find content, n next content, n previous content

Head command

Purpose: View part of the beginning of the file (default is 10 lines)

-n Specifies how many rows need to be displayed (n is the exact number of rows)

Tail command

Purpose: View a small portion of the end of the file (default is 10 lines)

-n Specifies how many rows need to be displayed (n is the exact number of rows)

WC command

Purpose: Information such as the number of words in the statistics file (Word Count)

Option:-L: Count rows

-W: Count the number of words

-C: Statistics of bytes

Format: WC option destination File

grep command

Purpose: Finds and displays lines containing the specified string in the file, retrieves, filters the contents of the file

Common Command Options

-I: Ignore case when finding

-V: Reverse lookup, output rows that do not match the lookup criteria

Find conditional settings

The string to find is enclosed in double quotation marks.

"^init" means start with init, "ftp$" means end with FTP

"^$" indicates a blank line

Format: grep option to find a conditional target file

Example: Grep-v "^#"/etc/inittab

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Linux Basic Command Notes (iii)