Shulou(Shulou.com)06/02 Report--

Learn the necessary commands of Linux (1) 1: what is Linux

The ​ Linux command is a command that manages the Linux system. For the Linux system, no matter the CPU, memory, disk drive, keyboard, mouse, or users are all files, the command managed by the Linux system is the core of its normal operation. There are two types of Linux commands on the system: the built-in shell command and the Linux command.

​ in the Linux operating system, it is important to note that linux commands (including file names, etc.) are case-sensitive, and if you enter the wrong command case, the system will not respond as you expect.

II: Linux command line format 1. General command line format

Command word [option] [parameter]

Option

Short format options: use the "-" symbol to guide multiple single-character options that can be combined (e.g. ls-l ls-al)

Long format command option: use the "- -" symbol to boot (for example:-- help).

Parameters.

Processing object of command word

It can be file name, directory name, user name, etc.

The number can be zero to more.

[root@localhost] # means:

​ root: currently logged in system user

​ @: delimiter

​ localhost: hostnam

​ ~: current directory location

​ # key: indicates administrator

​ $: ordinary user

2. Edit the Linux command line

Tab key: automatic completion

Backslash "\": force line feeds

Shortcut key Ctrl+U: clear to the beginning of the line u

Shortcut key Ctrl+K: clear to the end of the line

Shortcut key Ctrl+L: clear the screen

Shortcut key Ctrl+C: cancel editing this command

3. Ways to get help from commands

Internal commands help: view help information for Bash internal commands

-- help: for most external commands

Use the man command to read the manual: scroll the text using the up and down arrow keys

​ turns the page using the Page Up and Page Down keys

​ press Q or key to exit the reading environment and press "/" to find the content.

Third: common directory / file operation command 1, switch working directory cd

Cd. Switch to the target location

Cd ~ if you do not specify the target location, switch to the host directory of the current user

Cd-change to the directory where the last cd command was executed

Cd.. View the previous directory

Cd../../ check the upper directory.

Cd / root directory

2. Display directory list command ls

Ls-l displays the details of the file

Ls-a view hidden files

Ls-A looks at hidden files except..

Ls-d displays the information of this directory

Ls-h friendly form to display information with units

Ls-R reverse display (if there is a subdirectory, the subdirectory files will be shown in turn)

Pwd displays the user's current working directory

3. Distinguish file types by color

Blue-directories, folders red-compressed package green-executable files / command files / scripts

Sky blue-soft connection file / shortcut file huang color-device file / disk file black / white-data file

4. Statistical catalogue and file space occupancy du

Du [option] [file or directory]

-a count all files when disk space is occupied

-h displays statistical results (kB count by default)

-s only counts the total size of the space occupied, not the size of each subdirectory file

For example: du-sh / var/log/ statistics the total amount of space occupied by var/log files

5. Mkdir for directory creation

For example: mkdir test creates a test directory under the current directory

​ mkdir-p / aa/bb/cc creates a subdirectory bb under the directory aa,aa and cc under the BB subdirectory

6. File creation (touch) and deletion (rm)

Touch test.txt creates a test.txt file in the current directory

Touch demo {1... 10} .txt creates multiple new empty files

Rm-f test.txt directly deletes the text.txt file

Rm-r recursive deletion, that is, delete directories and subdirectories under their directories

Rm-rf directly deletes directories and subdirectories under their directories

7. Copy a file or directory cp

-f overwrite the target file with the same name without reminding, copy and paste directly

-I overwrite the target file with the same name and remind the user to confirm

-p keep the permissions of the source file when copying, and the attributes remain unchanged

-r must use this option when copying a directory, which means that all files are copied recursively

8. Find a data file or directory find

Find by file name-name

Find by file size-size

Find by file owner-user

Find by file type-type

File types: normal file (f), directory (d), block device file (b), character device file (c)

9. View the contents of the file

Cat displays the contents of the file from the first line

More displays the contents of a file page by page, which is used to display the file contents in full-screen paging mode.

Less is similar to more, but better than more, it extends more functions.

Head looks at the beginning of the file (default is 10 lines) example: head-n file name (n represents the number of lines)

Tail looks at a small portion of the end of the file

10. Wc of statistical file content

Information such as the number of words in a statistical file

-l count the number of rows

-w count the number of words

-c Statistics Bytes

Differences between ​ wc and du:

​ wc: how many statistics are made?

​ du: size of statistical files

11. File filing command tar

-C: create a compressed package-x: extract-f: execute-v: display the detailed process-p: retain the original file permissions

-t: view compressed content-C: unzipped path-Z:gzip format-j:bzip2 format

Compression commands: gzip, bzip2

-Q: high compression ratio-d: unzip the compressed file

12. Three working modes of vim editor

A: represents the insertion after the cursor

I: represents the insertion before the cursor

O: insert on the next line of the cursor

O: insert on the previous line of the cursor

Basic operation of command mode:

Home key or ^, the number 0: jump to the beginning of the file End key or $: jump to the end of the line 1G or gg: jump to the first line of the file

G: jump to the last line of the file # G: jump to line # of the file

Set nu displays the line number in the editor

: set nonu cancels line number

: set nu! Cancel the line number

13. The meaning of Linux startup level init0-6

Init 0: shutdown

Init 1: single user mode (only root for maintenance)

Init 2: multi-user mode without web character interface

Init 3: full multi-user mode with web character interface

Init 4: safe mode (reserved)

Init 5: multi-user mode graphical interface

Init 6: restart (reboot)

There are many commands to learn linux, you have to memorize and practice more to not forget, but also to understand the meaning of each command representative, you will know what you need to configure.

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