This paper is participating in the30 years of Linux”Topic essay activity

🌲 preface

Why learn Linux commands?

At present, more than 80% or even more systems in enterprises are Linux operating system, so whether it is development or operation and maintenance, it is impossible to work in enterprises without knowledge of Linux. Also, Linux proficiency is part of the job description in many companies.The direction of Linux is also relatively wide, mainly divided intooperations 和 The development of, subdivide down numerous, basic will be involved, so learn Linux urgent. This article is a summary of common Linux commands I’ve learned over the years! Very full! More detailed! Package learning package meeting!

🏆 Command Summary

🍇 File Management

1️ discount command – display content and property information under the specified working directory

The ls command is an abbreviation of the English word list. As the English word list means, its function is to list the contents of a specified directory and related attribute information.

By default, the ls command lists the contents of the current directory. With parameters, we can do a lot more with LS. As the most basic and frequently used command, it is important to know how to use the ls command, so let’s take a look.

Grammar:

Syntax: ls [option] [file]

Common parameters:

parameter	describe
-a	Display all files and directories (including “. Hidden files at the beginning)
-l	List file and directory information in long format
-r	Display files in reverse order (default alphabetical order)
-t	Sort by last modified time
-A	Same as -a, but without listing “. (current directory) and “..” (Parent directory)
-S	Sort by file size
-R	Recursively lists all subdirectories

Reference Examples:

List all files (including hidden files) :

ls -a
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List file details:

ls -l
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List all directories under root (/) :

ls /
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List all files in the current working directory whose names start with ‘s’ (excluding folders) :

ls -ltr s*
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List all directories and files in /root directory:

ls -lR /root
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List all files and directories in the current working directory and sort by file size:

ls -AS
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2️ retail command – copy files or directories

The cp command can be understood as the abbreviation of copy. It copies files or directories.

The cp command can copy multiple files to a specific file name or an existing directory, or to a specified directory at the same time.

Grammar:

Syntax: cp [parameter] [file]

Common parameters:

parameter	describe
-f	If the destination file already exists, the original file is overwritten
-i	If the target file already exists, it will ask whether to overwrite it
-p	Preserve all attributes of the source file or directory
-r	Recursively copy files and directories
-d	When a symbolic link is copied, the target file or directory is also set up as a symbolic link, pointing to the original file or directory connected to the source file or directory
-l	Hardwire source files instead of copying them
-s	Make symbolic links to source files instead of copying files
-b	Back up an existing file target before overwriting it
-v	The cp command is displayed in detail
-a	Equivalent to “DPR” option

Reference Examples:

Copy directory:

cp -R dir1 dir2/
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Rename file test1 to test2:

cp -f test1 test2
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Copy multiple files:

cp -r file1 file2 file3 dir
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Interactively copy all. C files in /home/lucifer to dir:

cp -r /home/lucifer/*.c dir
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3️ mkdir command – create a directory

The mkdir command is short for “make directories” and is used to create directories.

📢 Note: By default, if the directory to be created already exists, the system displays a message indicating that the directory already exists and does not continue to be created. Therefore, when creating a directory, ensure that the new directory does not have the same name as the files in the directory. Isn’t the mkdir command powerful enough to create multiple directories at the same time?

Grammar:

Syntax: mkdir [parameter] [directory]

Common parameters:

parameter	describe
-p	Create multilevel directories recursively
-m	When creating a directory, set the permission of the directory
-z	Setting the Security Context
-v	Shows the directory creation process

Reference Examples:

In the working directory, create a subdirectory named dir:

mkdir dir
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Create a subdirectory dir under the /home/lucifer directory and set the file owner to have read, write, and execute permissions.

mkdir -m 700 /home/lucifer/dir
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Create subdirectories dir1, dir2, dir3:

mkdir dir1 dir2 dir3
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Create a directory recursively:

mkdir -p lucifer/dir
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4️ discount command — move or rename files

The mv command is an abbreviation of the word “move”. It does much the same as it does in English: you can move or rename a file.

This is an overused file management command, and we need to pay special attention to the difference between it and copy: mv and CP have different results. The mv command looks like the file “move”, with the file name changed but the number of files not increased. The cp command is used to copy files and the number of files is increased.

Grammar:

Syntax: mv [parameter]

Common parameters:

parameter	describe
-i	If a file with the same name exists, the system asks the user whether to overwrite it
-f	When overwriting an existing file, no prompt is given
-b	When a file exists, create a backup of it before overwriting it
-u	This operation is performed only when the source file is newer than the destination file or the destination file does not exist

Reference Examples:

Rename file file_1 to file_2:

mv file_1 file_2
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Move the file file to the directory dir:

mv file /dir
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Move directory dir1 to directory dir2 (if directory dir2 already exists, rename it if it does not) :

mv /dir1 /dir2
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Move files from directory dir1 to the current directory:

mv /dir1/* .
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5️ PWD command – displays the current path

The PWD command is an acronym for each word in “print working Directory”. Its function is to print the working directory, that is, to display the absolute path of the current working directory.

In practice, we often switch between different directories. To prevent “getting lost”, we can use the PWD command to quickly see the directory path we are currently in.

Grammar:

Syntax: PWD [parameter]

Common parameters:

parameter	describe
-L	Display logical paths

Reference Examples:

View the current working directory path:

pwd
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🍉 Document editing

1️ retail command – display file content on terminal devices

The command “cat” is also easy to remember, because cat means “cat” in English. Does a kitten give you a feeling of being small and cute?

📢 Note: When the file content is large, the text will flash quickly on the screen (scrolling), and users often cannot see the specific content displayed.

Therefore, for longer file contents:

• Press Ctrl+S to stop scrolling;
• Press Ctrl+Q to resume scrolling;
• To terminate the command, press Ctrl+C (Interrupt).

Or for large files, use the more command.

Grammar:

Syntax: cat [parameter] [file]

Common parameters:

parameter	describe
-n	Display number of lines (blank lines are also numbered)
-s	Display number of lines (multiple blank lines count as one number)
-b	Display number of lines (blank lines are not numbered)
-E	The $sign is displayed at the end of each line
-T	Displays the TAB character as the ^I symbol
-v	Use ^ and M- references, except for LFD and TAB
-e	Equivalent to the “-ve” combination
-t	Equivalent to the “-vt” combination
-A	Equivalent to the -vet combination
–help	Display help information
–version	Display version Information

Reference Examples:

View the contents of the file:

cat lucifer.log
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View the contents of the file and display the line number:

cat -n lucifer.log
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View the contents of the file and add the line number to the output of another file:

cat -n lucifer.log > lucifer.txt
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Clear the contents of the file:

cat /dev/null > /root/lucifer.txt
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Continue writing the contents of the file, ending when EOF is encountered and saving:

cat > lucifer.txt <<EOF Hello, World Linux! EOF
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To make an image file of a floppy disk device:

cat /dev/fb0 > fdisk.iso
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2️ retail echo command – output string or extract the value of Shell variable

The echo command is used to output the extracted value of a string or variable on a terminal device. This is one of the most common commands in Linux, but the operation is very simple.

The value of a variable is extracted by adding a symbol to it. For example, the value of a variable is extracted by using a symbol, such as PATH, and then the echo command is used to output the value. Alternatively, use the echo command to output a string to the screen to prompt the user.

Grammar:

Echo [parameter] [string]

Common parameters:

parameter	describe
-n	No trailing newline character is printed
– e “\”	Sound a warning note
– e “\ b”	Deletes the preceding character
– e “\ c”	End without a newline character
– e “\ f”	Newline, the cursor stays at the original coordinate position
– e “\ n”	Newline, cursor moved to the beginning of the line
– e “\ r”	Cursor moves to the beginning of the line without newline
-E	Disallows backslash transfer, as opposed to the -e parameter
– the version	Viewing version Information
–help	Viewing Help Information

Reference Examples:

Print a string:

echo "Hello Lucifer"
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Output variable extracted value:

echo $PATH
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Escape the content to disallow the $symbol to extract the value of the variable:

echo \$PATH
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Import string information into a file with the output redirection:

echo "It is a test" > lucifer
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Execute the command with backquotes and print the result to the terminal:

echo `date`
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Output content with a newline character:

echo -e "a\nb\nc"
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Delete a character from the output. Note that the number 3 is missing:

echo -e "123\b456"
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3️ discount command – remove files or directories

The rm command is commonly used to delete one or more files or directories in a directory. It can also delete all files and subdirectories in a directory. For linked files, only the link is deleted, and the original files remain unchanged.

📢 Note: rm is also a dangerous command and should be used with extreme care, especially for beginners, otherwise the entire system will be destroyed by this command (e.g. Rm * -rf under/(root)).

Therefore, before executing rm, it is best to confirm which directory to delete and keep a high level of sanity.

Grammar:

Syntax: rm [parameter] [file]

Common parameters:

parameter	describe
-f	Ignore nonexistent files and no warning message appears
-i	The system asks the user whether to perform the deletion
-r/R	Recursive delete
-v	Display the detailed execution process of the command

Reference Examples:

Ask and confirm before deleting:

rm -i test.txt.bz2
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Delete directly without any prompt:

rm -f test.txt.bz2  
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Recursively delete a directory and all files in it:

mkdir /data/log
rm -rf /data/log
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Delete all files in current directory:

rm -rf *
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Clear all files from the system (caution) :

rm -rf /*
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4️ retail command – View the contents of the tail of the file

Tail Displays the contents at the end of a file. By default, the last 10 lines of a specified file are displayed on the screen. If more than one file is given, each file displayed is preceded by a filename title. If no file is specified or the file name is -, the standard input is read.

Grammar:

Syntax: tail [parameter]

Common parameters:

parameter	describe
–retry	Always try to open the file, either when the tail command starts or when the file becomes inaccessible later. Use this option in conjunction with the option — follow=name
– or – bytes = c	Output N (N is an integer) bytes of content at the end of the file
-f<name/descriptor>	–follow: Displays the latest content appended to the file
-F	This function is the same when used with the -follow=name and –retry options
N or — — – line =	The N (N digit) lines at the end of the output file
–pid=< process number >	When used with the -f option, the tail command automatically exits after the process with the specified process id terminates
–help	Displays help information for commands
–version	Displays the version information of the command

Reference Examples:

Display the last 10 lines of file:

tail file
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Display the contents of file from line 20 to the end of the file:

tail +20 file 
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Display the last 10 characters of file:

tail -c 10 file 
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Files that keep changing always show the last 10 lines:

tail -f 10 file
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Display help information:

tail --help
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5️ retail command – delete an empty directory

The rmdir command is used to remove an empty directory. Its full name is remove directory.

Note: the rmdir command can only delete empty directories. To delete a non-empty directory, use the rm command with the “-r” option.

The “-p” parameter of the rmdir command can recursively delete a specified multi-level directory, but each directory must also be empty.

Grammar:

Syntax: rmdir [parameter] [directory name]

Common parameters:

parameter	describe
-p	Delete all parent directories in the specified directory path recursively. If they are not empty, an error is reported
–ignore-fail-on-non-empty	Ignore error messages caused by command errors when deleting a non-empty directory
-v	Displays the detailed execution process of commands
–help	The help information about the command is displayed
–version	The command version information is displayed

Reference Examples:

Delete an empty directory:

rmdir dir
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Delete the specified directory tree recursively:

rmdir -p dir/dir_1/dir_2
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Display the detailed execution process of instructions:

rmdir -v dir
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Display the version information of the command:

rmdir --version
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🍋 System Management

1️ RPM command – RPM package manager

The RPM command is short for red-hat Package Manager (RPM Package Manager). It is used to manage software packages in Linux. In Linux, almost all software can be installed, uninstalled, and managed through RPM.

In summary, the RPM command contains five basic functions: install, uninstall, upgrade, query, and verify.

Grammar:

RPM [parameter] [package]

Common parameters:

parameter	describe
-a	Example Query all software packages
– b or – t	Sets the completion stage of the package and specifies the file name for the package file
-c	Only configuration configuration files are listed. This parameter must be used together with the -l parameter
-d	Only text files are listed. Use this parameter with the -l parameter
– or – e erase	Uninstalling software Packages
-f	Query the software package to which a file or command belongs
– h or – hash	List the tags when installing the package
-i	Displays information about software packages
–install	Installing software Packages
-l	The file list of the software package is displayed
-p	Example Query a specified RPM package
-q	Querying software Packages
-R	Displays software package dependencies
-s	Displays the file status. Use this parameter together with the -l parameter
-u or — the upgrade	Upgrade Software Packages
-v	The command execution process is displayed
-vv	Detailed display of command execution process

Reference Examples:

Direct installation package:

rpm -ivh packge.rpm 
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Ignore the error and force installation:

rpm --force -ivh package.rpm
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List all installed packages:

rpm -qa
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Query the installation location of files in RPM packages:

rpm -ql ls
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Uninstalling RPM packages:

rpm -e package.rpm 
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Upgrade package:

rpm -U file.rpm
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2️ find command – find and search files

The find command can find a file or directory based on a given path and expression. The find parameter has many options and is powerful with re support. Combined with pipes, it can achieve complex functions and is a command that system administrators and ordinary users must master.

If no parameter is added to find, all files and directories in the current path are searched. If the server load is heavy, do not run the find command during peak hours. Fuzzy search using the find command consumes system resources.

Grammar:

Syntax: find [parameter] [path] [search and search range]

Common parameters:

parameter	describe
-name	Search by name
-size	Search by size
-user	Search by property
-type	Search by type
-iname	Ignore case

Reference Examples:

Use the -name parameter to view all configuration files ending in the. Conf file in the /etc directory:

find /etc -name "*.conf
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Use the -size parameter to view files larger than 1M in the /etc directory:

find /etc -size +1M
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Find all files in the current user’s home directory:

find $HOME -print
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List all files and folders in the current directory and subdirectories:

find .
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Find the file names ending in.txt in /home:

find /home -name "*.txt"
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Ignore case in /var/log to find file names ending in.log:

find /var/log -iname "*.log"
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Search for all files that have been accessed for more than 7 days:

find . -type f -atime +7
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Search for all files that are accessed for more than 10 minutes:

find . -type f -amin +10
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Find files under /home that do not end in.txt:

find /home ! -name "*.txt"
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3️ startx command – initialize x-windows

Using the startx command, you can start the X-Window, which calls the initialization program xinit of the X-Window system. To complete the initialization necessary for x-Window to run and start the X-Window system.

Grammar:

Syntax format: startx [parameter]

Common parameters:

parameter	describe
-d	Specifies the display name of the X server that is passed to the client during startup
-m	When the startup script is not found, start the window manager
-r	When the startup script is not found, load the resource file
-w	Mandatory start
-x	Start an X-Windows session using the startup script

Reference Examples:

X-windows has been started by default:

startx
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Start X-Windows with 16-bit color depth:

startx --depth 16
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Forcibly starting x-Windows:

startx -w
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4️ disame command – displays system information

The full name of the uname command is Unix name.

Displays system information, such as the host name, kernel version, and hardware architecture.

If no option is specified, the effect is equivalent to executing the “uname -s” command, which displays the name of the system kernel.

Grammar:

Syntax: uname [parameter]

Common parameters:

parameter	describe
-a	Displays all system information
-m	Displays the computer hardware architecture
-n	Display host name
-r	Displays the kernel release number
-s	Display kernel name
-v	Display kernel version
-p	Display the host processor type
-o	The operating system name is displayed
-i	Display hardware platform

Reference Examples:

The system host name, kernel version, and CPU type are displayed.

uname -a
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Display only the system host name:

uname -n
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Display the kernel version of the current system:

uname -r
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Display the current system hardware architecture:

uname -i
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5️ vmstat command – Displays virtual memory status

The vmstat command is intended to display the status of Virtual Memory (” Virtual Memory Statistics “), but it can report the overall running status of the system, such as processes, Memory, AND I/O.

Grammar:

Syntax: vmstat [parameter]

Common parameters:

parameter	describe
-a	Display active inside pages
-f	Displays the total number of processes created after startup
-m	Display slab information
-n	Header information is displayed only once
-s	Displays event counters and memory status in a tabular manner
-d	Reporting Disk Status
-p	Displays the status of a specified disk partition
-S	Unit of output information

Reference Examples:

Display active inside pages:

vmstat -a
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Displays the total number of processes created after startup:

vmstat -f
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Display slab information:

vmstat -m
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Header information is displayed only once:

vmstat -n
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Display event counters and memory state in tabular form:

vmstat -s
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Displays the status of the specified hard disk partition:

vmstat -p /dev/sda1
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Specifies the interval between status information refreshes to 1 second:

vmstat 1
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🍑 Disk Management

1️ df command – displays disk space usage

The full name of the df command is Disk Free. As the name implies, the df command displays the available Disk space in the system. The default unit is KB. You are advised to use the df -h parameter combination to automatically change the unit based on the disk capacity.

This command is commonly used to check the occupied disk space and remaining disk space.

Grammar:

Syntax: df [parameter] [specify file]

Common parameters:

parameter	describe
-a	Display all system files
-B	< block size > specifies the block size for display
-h	Display in an easy-to-read manner
-H	Display in 1000 bytes as conversion units
-i	Displays index byte information
-k	Specify a block size of 1KB
-l	Only local file systems are displayed
-t	< File system type > displays only file systems of the specified type
-T	The file system type is displayed
— -sync	Before obtaining the disk usage information, run sync

Reference Examples:

Display disk partition usage:

df
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Display disk partition usage in an easy-to-read way:

df -h
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Displays the disk usage of the partition where the specified file resides:

df /etc/dhcp
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The usage of ext4 disks is displayed:

df -t ext4
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2️ retail fdisk command – disk partition

The full name of the fdisk command is “Partition table for Linux”, which serves as a disk Partition tool. Hard disk partition is essentially a format of the hard disk, with an image metaphor, partition is like drawing a big box on a piece of white paper, and formatting is like playing a grid in the box.

Grammar:

Syntax: fdisk [parameter]

Common parameters:

parameter	describe
-b	Specify the size of each partition
-l	Lists the partition table state of the specified peripheral
-s	Prints the specified partition size to standard output in blocks
-u	With the “-l” argument list, the number of partitions replaces the number of cylinders to indicate the starting address of each partition
-v	Display version Information

Reference Examples:

Query all partitions:

fdisk -l
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Select partition disk:

fdisk /dev/sdb
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Create an extended partition on the current disk:

fdisk /ext
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Speed up partitioning without checking disk surface:

fdisk /actok
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Rebuild master boot record:

fdisk /cmbr
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3️ discount BLK command – View disk of the system

The LSBLK command, which is called “list block”, lists all available block devices and shows their dependencies, but it does not list RAM disks.

The LSBLK command was included in the util-linux-ng package, now renamed util-linux.

Grammar:

Syntax: LSBLK [parameter]

Common parameters:

parameter	describe
-a	Display all devices
-b	Displays the device size in bytes
-d	Do not display slaves or holders
-D	print discard capabilities
-e	Rule out equipment
-f	The file system information is displayed
-h	Display help information
-i	use ascii characters only
-m	Display Permission Information
-l	Display in list format
-n	Don’t show title
-o	Output columns
-P	The value is displayed in the key= value format
-r	Display in raw format
-t	Display topology information

Reference Examples:

By default, the LSBLK command lists all block devices in a tree:

lsblk
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The default option does not list all empty devices:

lsblk -a
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Can also be used to list ownership relationships for a particular device, as well as groups and patterns:

lsblk -m
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To get a list of SCSI devices, you can only use the -s option, which is used to print dependencies in reverse order:

lsblk -S
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For example, you might want to list devices in a list format rather than the default tree format. You can combine two different options to get the desired output:

lsblk -nl
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4️ hdparm command – display and setting disk parameters

The hdparm command is used to detect, display, and set the parameters of IDE or SCSI disks.

Grammar:

Syntax: hdparm [parameter]

Common parameters:

parameter	describe
-a	Set the number of blocks to be pre-stored when reading a file
-f	Writes data from the memory buffer to the disk and clears the buffer
-g	Display hard disk track, magnetic head, magnetic area and other parameters
-I	Read hardware specifications information provided by hard disks
-X	Set the hard drive transfer mode

Reference Examples:

Display hard drive Settings:

hdparm /dev/sda
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Display the number of cylinders, heads, and sectors of the hard disk:

hdparm -g /dev/sda
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Evaluate hard disk read efficiency:

hdparm -t /dev/sda
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Read the hardware specifications provided by the hard disk directly:

hdparm -X /dev/sda
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Put IDE hard disk into sleep mode:

hdparm -Y /dev/sda
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5️ vgextend command – extend volume group

The vgextend command is used to dynamically expand an LVM volume group by adding physical volumes to the volume group. Physical volumes in an LVM volume group can be added when a volume group is created using the vgcreate command or added dynamically using the vgextend command.

Grammar:

Syntax format: vgextend [parameter]

Common parameters:

parameter	describe
-d	Debug mode
-t	Only testing

Reference Examples:

Add physical volume /dev/sdb1 to volume group vgLinuxprobe:

vgextend vglinuxprobe /dev/sdb1
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🍓 File transfer

1️ TFTP command – upload and download files

The TFTP command is used to transfer files. FTP allows users to download and upload files stored on a remote host.

TFTP is a simple text-mode FTP program that uses instructions similar to FTP.

Grammar:

Syntax: TFTP [parameter]

Common parameters:

parameter	describe
connect	Connect to the remote TFTP server
mode	File transfer mode
put	Upload a file
get	The download file
quit	exit
verbose	Displays detailed processing information
trace	Display package path
status	Display current status information
binary	Binary transmission mode
ascii ascii	Transfer mode
rexmt	Set the timeout period for packet transmission
timeout	Set the timeout period for retransmission
help	Help information
?	Help information

Reference Examples:

Connecting to the remote server 10.211.55.100:

TFTP 10.211.55.100Copy the code

Remote download file:

tftp> get file
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Exit the TFTP:

tftp> quit 
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2️ retail command – file transfer tool

The curl command is a file transfer tool that uses URL rules to work in the command line of shell terminal. Curl supports uploading and downloading files, so it is a comprehensive transfer tool.

Curl supports HTTP, HTTPS and FTP. It also supports POST, cookies, authentication, downloading files from specified offsets, user agent strings, speed limits, file sizes, and progress bars. Automate web page processing and data retrieval.

Grammar:

[url] curl [url]

Common parameters:

parameter	describe
-O	Write the output to the file, keeping the name of the remote file
-u	Access is authorized by the user name and password configured on the server

Reference Examples:

To write downloaded data to a file, you must use the absolute address of the file:

curl https://www.baidu.com /root/lucifer.txt --silent -O
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When accessing pages that require authorization, you can use the -u option to provide the user name and password for authorization.

curl -u root https://www.baidu.com/
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3️ FSCK command – check and repair the Linux file system

The full name of the FSCK command is filesystem check, which is used to check and repair errors in the Linux filesystem. Before operating a filesystem, back up important data to prevent loss.

The Linux FSCK command is used to check and repair Linux file systems. You can check one or more Linux file systems simultaneously. If the system is powered off or the disk is faulty, run the FSCK command to check the file system.

Grammar:

Syntax: FSCK [parameter] [file system]

Common parameters:

parameter	describe
-a	Automatic file system repair, no questions asked
-A	Check all file systems listed in the /etc/fstab configuration file
-N	No instructions are executed, only the actions that are actually executed are listed
-P	If the -a parameter is used, all file systems are checked at the same time
-r	Use interactive mode to ask questions when performing fixes so that users can confirm and decide what to do
-R	If the parameter -a is used, the file system in the/directory is ignored
-t	Specifies the type of file system to check
-T	When the FSCK command is executed, no title information is displayed
-V	Display command execution process

Reference Examples:

Fix bad partitioned file system:

fsck -t ext3 -r /usr/local
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Display the version number of FSCK system installed:

fsck --version
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4️ discount command – Displays FTP session information

The ftpwho command is used to display the session information of all FTP login users.

You can run this command to know who the current FTP login users are and what operations they are performing.

Grammar:

Syntax: ftpwho [parameter]

Common parameters:

parameter	describe
-h	Display help information
-v	Detailed mode, output more information

Reference Examples:

To query the current user who is logging in to the FTP server:

ftpwho
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In detailed mode, query the current user who is logging in to the FTP server.

ftpwho -v
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Display help information:

ftpwho -h
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5️ LPRM command – Delete the print task in the print queue

The full name of the LPRM command is Remove jobs from the print queue, which is used to delete print jobs from the print queue. Unfinished printer work is placed in the printer store column. This command can be used to cancel work that has not been sent to the printer.

Grammar:

Syntax: LPRM [parameter] [Task number]

Common parameters:

parameter	describe
-E	Enforces encryption when connecting to the print server
-P	Specifies the target printer to receive the print task
-U	Specify an optional user name

Reference Examples:

Remove task 102 from hpPrint printer:

lprm -Phpprint 102
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Remove task 101 from the preset printer:

lprm 101
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🌽 Network Communication

1️ SSH command – Securely connecting clients

The SSH command is a client connection tool in the OpenSSH suite. It enables secure remote login to and remote management of the server using the SSH encryption protocol.

Grammar:

SSH [parameter] [remote host]

Common parameters:

parameter	describe
– 1	The SSH protocol version 1 is mandatory
2 –	The SSH protocol version 2 is mandatory
4 –	An IPv4 address is mandatory
– 6	The IPv6 address is mandatory
-A	The authentication proxy connection forwarding function is enabled
-a	Disable the connection forwarding function of the authentication proxy
– b < IP address >	The IP address specified by the local host is used as the source IP address for the peer connection
-C	Request compression of all data
-f < Configuration file >	Specifies the configuration file of the SSH directive. The default configuration file is /etc/ssh/ssh_config.
-f	The SSH command is executed in the background
-g	Allows a remote host to connect to a forwarding port on the local host
-i< identity file >	Specify an identity file (private key file)
-l< login name >	Specifies the login user name to connect to the remote server
-N	Do not execute remote commands
-o < option >	Specify configuration options
-p < port >	Specifies the port on the remote server
-q	In silent mode, all warning and diagnostic messages are disabled
-X	The X11 forwarding function is enabled
-x	The X11 forwarding function is disabled
-y	Enable the trusted X11 forwarding function

Reference Examples:

Log in to the remote server:

SSH 10.211.55.100Copy the code

Connect to remote server as user test:

ssh -l test 10.211.55.100
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To view the partition list:

SSH 10.211.55.100 / sbin/fdisk -lCopy the code

Forced SSH version 1:

ssh -1
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Enable the authentication proxy connection forwarding function:

ssh -A
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2️ netstat command – display network status

The netstat command is used to display various network-related information, such as network connections, routing tables, Interface Statistics, Masquerade connections, and Multicast Memberships.

The output of netstat can be divided into two parts. One is Active Internet Connections, called Active TCP connections, where “recv-q” and “send-q” refer to %0A for receiving and sending queues. These numbers should always be 0. If not, it indicates that the software package is piled up in the queue. This happens only very rarely; The other is Active UNIX Domain Sockets, called Active UNIX Domain Sockets (the same as network sockets, but only for native communication, with twice the performance).

Grammar:

Syntax: netstat [parameter]

Common parameters:

parameter	describe
-a	Displays the sockets of all connections
-p	Displays the program identifier and program name that is using the Socket
-u	Displays the connection status of the UDP transport protocol
-i	The network page information list is displayed
-n	Use the IP address directly, not the DNS server

Reference Examples:

Display detailed network status:

netstat -a
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Display current household UDP connection status:

netstat -nu
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Display UDP port number usage:

netstat -apu 
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Display network card list:

netstat -i
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Display the relationship between multicast groups:

netstat -g
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3️ ping command – Test network connectivity between hosts

The ping command is used to test the connectivity between hosts. After the ping command is executed, ICMP is used to send a message requesting a response. If the remote host is running properly, the remote host responds to the message.

It is worth noting, however, that the ping command on Linux is slightly different from the ping command on Windows. In Windows, four requests are sent before the ping command is run. Linux does not terminate automatically. In this case, press CTR+C or use -c to specify the number of requests to be sent in the ping command.

Grammar:

Ping [parameter] [destination host]

Common parameters:

parameter	describe
-d	Use the SO_DEBUG function of the Socket
-c	Specifies the number of times packets are sent
-i	Specifies the interval for sending and receiving messages
-I	Sends packets using the specified network interface
-l	Sets the packet that is sent before the requested message is sent
-n	Output only values
-p	Sets the template style for filled packets
-q	Command execution process is not displayed
-R	Recording the Routing Process
-s	Sets the size of the packet
-t	Set the TTL value
-v	Detailed display of command execution process

Reference Examples:

Check the connectivity with Baidu website:

ping www.baidu.com
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Ping4 times:

ping -c 4 www.baidu.com 
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Set The Times to 4 and the interval to 3 seconds:

ping -c 4 -i 3 www.baidu.com
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Use the ping command to obtain the IP address of the specified website:

ping -c 1 baidu.com | grep from | cut -d "" -f 4
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4️ dhclient command – dynamically obtain or release IP address

The dhclient command is used to dynamically configure network parameters for a network interface using the Dynamic host configuration protocol (BOOTP).

Grammar:

Dhclient [parameter] [network interface]

Common parameters:

parameter	describe
-p	Specify the port on which the DHCP client listens (default port 86)
-d	Always run the program in console mode
-q	In quiet mode, no error message is displayed
-r	Releasing IP Addresses
-n	No interface is configured
-x	To stop the running DHCP client without releasing the current lease, kill the existing DHclient
-s	Specify the DHCP server before obtaining the IP address
-w	The operation continues even if no broadcast interface is found

Reference Examples:

Sends a DHCP request on a specified network interface:

dhclient eth0
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Release IP address:

dhclient -r
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Get the IP address from the specified server:

Dhclient -s 10.211.55.100Copy the code

Stop dhClient:

dhclient -x
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5️ ifconfig command – display or set network equipment

The ifconfig command is called Network interfaces configuring, which is used to configure and display the network parameters of the network interfaces in the Linux kernel. The nic information configured by using the ifconfig command does not exist after the nic is restarted. In order to keep the above configuration information permanently stored in the computer, it is necessary to modify the network card configuration file.

Grammar:

Syntax: ifconfig [parameter]

Common parameters:

parameter	describe
Add the < address >	Example Set the IPv6 IP address of the network device
Del < address >	Example Delete the IPv6 IP address of the network device
down	Disable the specified network device
up	Starts the specified network device
The IP address	Specify the IP address of the network device

Reference Examples:

Display network device information:

ifconfig
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Enable or disable a specified nic:

ifconfig eth0 down
ifconfig eth0 up 
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Configure and delete aN IPv6 address for a network adapter:

ifconfig eth0 add 33ffe:3240:800:1005::2/64
ifconfig eth0 del 33ffe:3240:800:1005::2/64
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Change the MAC address with ifconfig:

ifconfig eth0 down
ifconfig eth0 hw ether 00:AA:BB:CC:DD:EE
ifconfig eth0 up
ifconfig eth1 hw ether 00:1D:1C:1D:1E 
ifconfig eth1 up
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Configure the IP address:

Ifconfig eth0 192.168.1.56 ifconfig eth0 192.168.1.56 netmask 255.255.255.0 ifconfig eth0 192.168.1.56 netmask 255.255.255.0 broadcast 192.168.1.255Copy the code

🍒 Device Management

1️ mount command – file system mount

The mount command is used to mount a file system to a specified loading point. The most common use of this command is to mount the CDROm, so that we can access the data in the Cdrom, because you insert the CD into the CDROm, Linux does not mount automatically, you must use the Linux mount command to do this manually.

Grammar:

Syntax: mount [parameter]

Common parameters:

parameter	describe
-t	Specify the mount type
-l	The list of loaded file systems is displayed
-h	Display help information and exit
-V	Show program version
-n	Load a file system that is not written to the /etc/mtab file
-r	Load the file system into read-only mode
-a	Load all file systems described in the /etc/fstab file

Reference Examples:

View version:

mount -V
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Start all mounts:

mount -a
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Mount /dev/cdrom to/MNT:

mount /dev/cdrom /mnt
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Mount an NFS file system:

mount -t nfs /123 /mnt
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Mount the first partition of the first disk to /etc directory:

mount -t ext4 -o loop,default /dev/sda1 /etc
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2️ MAKEDEV command — build the device

MAKEDEV is a script that sets up devices in the /dev directory, through which drivers located in the kernel can be accessed.

The MAKEDEV script creates static device nodes, usually in the /dev directory.

Grammar:

Syntax: MAKEDEV [parameter]

Common parameters:

parameter	describe
-v	Displays every action performed
-n	No real updates, just to show how it works
-d	Deleting device Files

Reference Examples:

Displays each action performed:

./MAKEDEV -v update
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Delete a device:

./MAKEDEV -d device
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3️ LSPCI command – display information on all PCI buses on the current device

The lspci command is used to display information about all PCI buses and connected PCI devices on the host. Now mainstream devices such as network card storage are using PCI bus

Grammar:

Syntax: lSPCI [parameter]

Common parameters:

parameter	describe
-n	Display PCI vendor and device codes digitally
-t	Hierarchical relationships of PCI devices are displayed in a tree structure
-b	Bus-centric view
-s	Only the device and function block information of the specified bus slot is displayed
-i	Specifies the PCI number list file, not the default file
-m	Display PCI device information in a machine-readable manner

Reference Examples:

Display all PCI bus information of the current host:

lspci
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Display hierarchical relationships of PCI devices in tree structure:

lspci -t
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4️ discount command – setting the state of three leds on the keyboard

Setleds is a combination of the English phrase “setleds”, which translates into “set LEDS” in Chinese. Using the setleds command, you can set the status of the three LEDS above the keyboard. In Linux, each virtual console has its own Settings.

This is a very magical command, should be able to control the keyboard through the command of the lamp state. So let me learn this command.

Grammar:

Syntax format: setleds [parameter]

Common parameters:

parameter	describe
-F	Set the state of the virtual console
-D	Change virtual console state and preset state
-L	Change LED display state directly
+num/-num	Turn numeric keys on or off
+caps/-caps	Turn the case key on or off
+scroll /-scroll	Turn the option key on or off

Reference Examples:

Control keyboard indicator NUM On and off:

setleds +num 
setleds -num 
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The upper and lower case keys of the keyboard are on or off, and the keyboard indicator is on and off:

setleds +caps 
setleds -caps 
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Control the option key of the keyboard on or off, keyboard indicator light on and off:

setleds +scroll 
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Combination of the three lights on and off, respectively set as digital light on, upper and lower case light off, option key Scroll light off:

setleds +num -caps -scroll
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5️ sensors command — detect server internal temperature and voltage

Sensors command is used to detect the health of the internal cooling system of the server, monitor the motherboard, CPU operating voltage, fan speed, temperature, etc.

Grammar:

1. Sensors

Reference Examples:

Test CPU operating voltage, temperature, etc. :

sensors
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🍍 Backup compression

1️ discount zip command – compress files

The ZIP program puts one or more compressed files into a compressed archive along with information about the file (name, path, date, time of last modification, protection, and check information to verify file integrity). You can use a single command to package the entire directory structure into a ZIP archive.

For text files, compression ratios of 2:1 and 3:1 are common. Zip has only one compression method (deflation) and can store files without compression. Zip can also be compressed using BZIP 2 if bZIP 2 support is added, but these entries require a reasonable modern decompression to decompress. When bZIP 2 compression is selected, it replaces deflation with the default method. Zip automatically selects the better two files (deflated or stored, or bzip2 or Store if bzip2 is selected) for each file to be compressed.

Grammar:

Syntax format: zip [parameter] [file]

Common parameters:

parameter	describe
-q	Command execution process is not displayed
-r	Recursive processing, all files in the specified directory and subdirectories are processed together
-z	Annotate the compressed file
-v	Display command execution process or display version information
-n< tail string >	Does not compress a file with a particular tail-string

Reference Examples:

Package all files and folders in /home/html/ as html.zip in the current directory:

zip -q -r html.zip /home/html
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Delete file a.c from cp. Zip:

zip -dv cp.zip a.c
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Mydata: /home: mydata.zip mydata: /home: mydata.zip

zip -r mydata.zip mydata
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Zip the ABC folder and 123.txt under /home to abc123.zip:

zip -r abc123.zip abc 123.txt 
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Package the logs directory as log.zip:

zip -r log.zip ./logs
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2️ zipinfo command – View compressed file information

The full name of the zipinfo command is zip Information. This command is used to list information about compressed files. You can run the zipinfo command to obtain details about zip files.

Grammar:

Syntax format: zipinfo [parameter]

Common parameters:

parameter	describe
– 1	Only file names are listed
2 –	This parameter has the same effect as the “-1” parameter, but can be used with “-h”, “-t”, and “-z” parameters
-h	Only file names of compressed files are listed
-l	This parameter has the same effect as specifying the “-m” parameter, but lists the size of the original file instead of the compression rate of each file
-m	The effect of this parameter is similar to specifying the “-s” parameter, but it lists the compression rate for each file
-M	If the information content is more than one screen, the information is listed in a way similar to the MORE command
-s	List compressed file contents with an effect similar to executing the “ls -l” command
-t	Only the number of files in the compressed file, file size before and after compression, and compression ratio are listed
-T	List the date and time of each file in the compressed file in year, month, day, hour, minute, and second order
-v	Displays detailed information about each file in the compressed file
-x< Template Style >	Does not list information about eligible files
-z	If the compressed file contains comments, the comments are displayed

Reference Examples:

Display compressed file information:

zipinfo file.zip 
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Displays information about each file in the compressed file:

zipinfo -v file.zip
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Display only compressed package size and file number:

zipinfo -h file.zip
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Generate a basic, long-form list (rather than a lengthy one) with headings and summary lines:

zipinfo -l file
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View the most recently modified files in the archive:

Zipinfo -t file | sort - nr - 7 k | sed 15 qCopy the code

3️ unzip command – Decompress the ZIP file

The unzip command is a decompression tool for. Zip files. The unzip command will list, test, or extract files from zip archives typically located on MS-DOS systems.

The default behavior (i.e., no option) is to extract all files from the specified ZIP archive into the current directory (and subdirectories below). A companion program zip (1L) creates zip archives; Both programs are compatible with PKWARE’s PKZIP and PKUNZIP archive files created for MS-DOS, but in many cases the program options or default behavior are different.

Grammar:

Syntax: unzip [parameter] [file]

Common parameters:

parameter	describe
-l	Displays the files contained in the compressed file
-v	Displays detailed information at execution time
-c	Displays the results of the decompression on the screen, converting the characters as appropriate
-n	Do not overwrite the original file when decompressing
-j	Does not process the original directory path of the compressed file

Reference Examples:

Unzip mydata.zip from /home to myDatabak:

unzip mydata.zip -d mydatabak 
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Unzip the wwwroot. Zip file from /home to /home:

unzip wwwroot.zip
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Zip, abc23. Zip, abc34. Zip from /home to /home:

unzip abc\*.zip
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View the contents of wwwroot. Zip under /home:

unzip -v wwwroot.zip
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Verify that wwwroot. Zip is complete under /home:

unzip -t wwwroot.zip
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4️ gzip command – compress and decompress files

The gzip command is commonly used to compress files. Gzip is a widely used compression program. After files are compressed, their names are followed by multiple “.

Gzip is a command used to compress and decompress files in Linux. It is convenient and easy to use. Not only can gzip be used to compress large, lesser-used files to save disk space, it can also be used together with tar to form a popular compressed file format for Linux operating systems. According to statistics, the gzip command has a compression rate of 60% to 70% for text files. Reducing file size has two obvious benefits. One is that it reduces storage space, and the other is that when transferring files over the network, it reduces transfer time.

Grammar:

Syntax format: gzip [parameter]

Common parameters:

parameter	describe
-a	Use ASCII text mode
-d	Unzip the file
-f	Forcibly compress files
-l	This section describes the information about compressed files
-c	Output compressed files to standard output devices without altering the original files
-r	Recursive processing, all files and subdirectories under the specified directory are processed together
-q	No warning message is displayed

Reference Examples:

Zip each file in the rancher-v2.2.0 directory into a. Gz file:

gzip *
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Unzip each compressed file in the above example and list the details:

gzip -dv *
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Decompress the directory recursively:

gzip -dr rancher.gz
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5️ unarj command – decompress. Arj file

The unarj command is used to decompress. Arj files.

Grammar:

Syntax: unarj [parameter] [.arj compressed file]

Common parameters:

parameter	describe
-e	Unzip the. Arj file
-l	Displays the files contained in the compressed file
-t	Check whether the compressed file is correct
-x	Retain the original path when decompressing

Reference Examples:

Unzip.arj files:

unarj -e test.arj
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Show the files contained in the compressed file:

unarj -l test.arj
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Check whether the compressed file is correct:

unarj -t test.arj
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Keep the original path when decompressing:

unarj -x test.arj
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Unzip the file to the current path:

unarj -ex test.arj
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🍌 Other Commands

1️ hash command – Display and clear hash table queries on command run

The hash command displays and clears hash tables that are preferentially queried by the system when commands are run.

When the hash command is executed without specifying an argument or flag, the hash command reports the contents of the list of pathnames to standard output. This report contains the pathnames of commands in the current shell environment found by previous hash command calls. It also contains commands that are invoked and found through the normal command search process.

Grammar:

Syntax: Hash [parameter] [directory]

Common parameters:

parameter	describe
-d	Clear records in a hash table
-l	Displays the commands in the hash table
-p < > directive	Adds a command with a full path to the hash table
-r	Clears records in the hash table
-t	Displays the full path of the command in the hash table

Reference Examples:

To display commands in a hash table:

hash -l 
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Delete command from hash table:

hash -r 
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Add command to hash table:

hash -p /usr/sbin/adduser myadduser 
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To clear a record in a hash table:

hash -d
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Displays the full path of the commands in the hash table:

hash -t
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2️ grep command – a powerful text search tool

Grep is short for “Global Search Regular Expression and print out the line”, which means to search the regular expression thoroughly and print it out. This command can be used in conjunction with regular expressions and is the most widely used command on Linux.

Grep options are used to supplement the search process, and the command pattern is flexible, including variables, strings, and regular expressions. Note that when a pattern contains Spaces, always enclose them in double quotes.

Linux supports three forms of grep. The first is grep, standard and imitation. The second son has many interests. -egrep, which is equivalent to grep -e, supports basic and extended regular expressions. -fgrep, which is equivalent to grep -f, does not support regular expressions and matches the literal meaning of the string.

Grammar:

Syntax: grep [parameter]

Common parameters:

parameter	describe
-i	Ignore case when searching
-c	Only the number of matching rows is printed
-l	Only the file names that match are listed, not the specific matching lines
-n	Lists all matching rows, showing line numbers
-h	The file name is not displayed when multiple files are queried
-s	Does not display error messages that do not exist or have no matching text
-v	Displays all lines that do not contain matching text
-w	Match the words
-x	Match the entire line
-r	Recursive search
-q	Disable output of any results, exit status indicates whether the search was successful
-b	Prints the offset, in bytes, of the header of a matching line-spacing file
-o	Used with -b, prints the offset, in bytes, of the header of the matching data file

Reference Examples:

Support for multiple file queries and use of wildcards:

grep zwx file_* /etc/hosts
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Print the number of matching string lines:

grep -c zwx file_*
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List all matching lines and display line numbers:

grep -n zwx file_*
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Display all lines that do not contain patterns:

grep -vc zwx file_*
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No longer displays file names:

grep -h zwx file_*
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List only the filenames that match, not the rows that match:

grep -l zwx file_*
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Do not display non-existent or non-matching text messages:

grep  -s zwx file1 file_1
grep zwx file1 file_1
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Recursive search, not only for the current directory, but also for subdirectories:

grep -r zwx file_2 *
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To match the whole word, to interpret it literally, is equivalent to an exact match:

grep zw* file_1
grep -w zw* file_1
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Matches the entire line. The entire line in the file is printed only if it matches the pattern:

grep -x zwx file_*
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No result is output, exit status indicates the result:

grep -q zwx file_1
echo $?
grep -q zwx file_5
echo $?
grep -q zwx file5
echo $?
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Find empty and non-empty lines in a file:

grep -c ^$ file_1
grep -c ^[^$] file_1
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Match any or repeated characters with “. Or the “*” symbol to implement:

grep ^z.x file_1
grep ^z* file_6
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3️ wait command — one’s orders

The wait command is used to wait for an instruction until it is executed and then returns to the terminal. This command is often used in shell scripting. After the specified command is executed, the next task can be continued. When this instruction waits for a job, the backup number “%” must be added before the job ID.

Grammar:

Syntax: wait [parameter]

Common parameters:

parameter	describe
22 or % 1	Process ID or job ID

Reference Examples:

Wait for job 1 to complete and then return:

wait %1
find / -name password
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4️ retail BC command – floating point operation

BC, spelled “Binary Calculator”, is a Calculator language that supports interactive execution with arbitrary precision. Bash has built-in support for integer quarts, but it does not support floating-point arithmetic, and BC makes floating-point arithmetic very easy, and integer arithmetic is no longer a problem.

Grammar:

Syntax format: BC [option]

Common parameters:

parameter	describe
-i	Force into interactive mode
-l	Define the standard math library to use
-w	Define the standard math library to use
-q	Print normal GNU BC environment information

Reference Examples:

Arithmetic operations Advanced operations BC command it can perform floating point operations and some advanced functions:

echo "1.212 * 3" | bc 
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Set decimal precision (numeric range) :

echo "scale=2; 3/8" | bc
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Calculate square and square roots:

echo "10 ^" | bc
echo "sqrt(100)" | bc
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5️ history command — display and manipulate history command

The history command is used to display the history commands that a user has executed. You can add or delete the history commands.

If you use Linux commands a lot, using the history command is a great way to increase your productivity.

Grammar:

Syntax: history [parameter] [directory]

Common parameters:

parameter	describe
-a	Appends the history commands of the current shell session to the command history file, which is the configuration file that holds the history commands
-c	Clear the current history command list
-d	Deletes a command with a specified sequence number from the history command list
-n	Read history commands that were not read at the start of this Shell session from the command history file
-r	Read the command history file into the current Shell history command memory buffer
-s	Adds the specified command as a separate entry to the command history memory buffer. Delete the last command in the command history memory buffer before performing add
-w	Writes the contents of the current shell history command memory buffer to the command history file

Reference Examples:

Display the last 10 commands:

history 10
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Write the login command to the history file:

history -w
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Read the contents of the command history file into the current shell’s history memory:

history -r
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Append the current Shell session history command to the command history file:

history -a
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Clear the current history command list:

history -c 
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