Must-see Linux commands (summary)

What is Linux

Linux commands are commands for managing Linux systems. For a Linux system, whether it is the central processor, memory, disk drive, keyboard, mouse, or user, they are all files, and the commands for Linux system management are the core of its normal operation. There are two types of Linux commands in the system: built-in shell commands and Linux commands.

In the Linux operating system, one thing to note is that Linux commands (including file names, etc.) have requirements for capitalization. If the entered command has incorrect capitalization, the system will not will produce the response you expect.

Linux command line format

1. Common command line format

命令字 【选项】 【参数】

Options

Short format options: Use the "-" symbol to guide multiple single-character options that can be used together (such as: ls -l ls -al);

Long format command options: Use the "--" symbol to guide (such as: --help).

Parameters

The processing object of the command word;

can be a file name, directory name or user name, etc.;

The number can be zero to multiple.

[root@localhost ~]# means:

root: currently logged in system user

@: delimiter

localhost: host name

~: The current directory location

# key: Indicates the administrator

$: Ordinary user

2, Linux command line Edit

Tab key: Automatically complete

Backslash " \ ": Force a line break

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 this command editing

3. How to get command help

Internal command help: View help information for Bash internal commands

--help: Applicable to most external commands

Man command to read the manual: Use the up and down arrow keys to scroll the text;

Use the Page Up and Page Down keys to turn pages;

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

Common directory/file operation commands

1. Switch the working directory cd

cd. Switch to the target location

cd ~ If the target location is not specified, switch to the current user's home directory

cd - Switch to the directory where the cd command was last executed

cd.. View the upper directory

cd../../ View the upper directory

cd / root directory

2. Display directory list command ls

ls -l displays file details

ls -a View hidden files

ls -A View hidden files except...

ls -d displays information about this directory

ls -h displays information with units in a friendly form

ls -R displays in reverse (if there are subdirectories, the subdirectories will be Files are displayed in sequence)

pwd displays the user’s current working directory

3. Use color to distinguish file types

Blue----Directory, Folder red ---- compressed package green ---- executable file/command file/script

sky blue ---- soft link file/shortcut file yellow ---- device file/disk File black/white----data file

4, statistics directory and file space usage du

du [Option] [File or directory]

-a Count all files when disk space is occupied

-h Display the statistical results (counted in kB by default)

-s Only count the total size of the occupied space, not statistics The size of each subdirectory file

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

5. Directory creation mkdir

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

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

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

touch test.txt Create a test.txt file in the current directory

touch demo {1..10}.txt Create multiple new empty files

rm -f test.txt Directly delete the text.txt file

rm -r Recursively delete, that is Delete the directory and its subdirectories

rm -rf Directly delete the directory and its subdirectories

7, copy the file or directory cp

-f Overwrites the target file with the same name and does not prompt, copy and paste directly

-i Overwrites the target file with the same name and prompts the user to confirm

-p Keeps the permissions of the source file when copying, and the attributes are not Change

-r This option must be used when copying a directory, which means recursively copy all files

8. Find data files or directoriesfind

By file Name search-name

Search by file size-size

Search by file owner-user

Search by file type-type

File type: Ordinary file (f), directory (d), block device file (b), character device file (c)

9. View file content

cat displays the file content starting from the first line
more Displays the file content page by page, used to display the file content in pages in full screen mode
less is similar to more, but is better than more in terms of extended functions More
head View part of the content at the beginning of the file (default 10 lines) Example: head -n file name (n indicates which line)
tail View a small part of the content at the end of the file

10. Statistics of file content wc

Statistics of the number of words in the file and other information

-l Statistics of the number of lines

-w Statistics of the number of words

-c Count the number of bytes

The difference between wc and du:

wc: The number of statistical contents

du: The size of the statistical file

11. File archiving command tar

-C: Create compressed package -x: Decompress -f: Execute -v: Show detailed process -p: Keep original file permissions

-t: View the compressed content -C: Decompression path -Z: gzip format -j: bzip2 format

Compression command: gzip, bzip2

-q: High compression ratio -d: Unzip the compressed file

12. Three working modes of vim editor

a: represents after the cursor. Insert

i: Insert

before the cursor. o: Insert

in the next line under the cursor. O: Insert

## in the line above the cursor. #Basic operations in command mode:

home key or ^, 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 end of the file First line

G: jump to the end line of the file #G: jump to the #th line of the file

: set nu displays the line number in the editor

:set nonu Cancel 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 (root only) for maintenance)

init 2: Multi-user mode without network character interface

init 3: Full multi-user mode with network character interface

init 4: Safe mode (reserved)

init 5: Multi-user mode graphical interface

init 6: Reboot

There are many commands to learn Linux. You need to memorize and practice more so that you will not forget them. , you also need to understand the meaning of each command to know what you need to configure.

For more Linux knowledge, please visit the

Linux Tutorial column!

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