Common command review,

Common command review,

Man	View Command help, command dictionary, more complex info, but not commonly used.
Help	View the help of Linux built-in commands, such as the cd command.
File and directory operation commands (18)
Ls	The full list function is to list the contents of a directory and its content attributes.
Cd	The change directory function is to switch from the current working directory to the specified working directory.
Cp	The full copy function is to copy files or directories.
Find	It is used to find the Directory and files in the directory.
Mkdir	Make directories. Its function is to create a directory.
Mv	The function of moving all files is to move or rename files.
Pwd	Print working directory, which is used to display the absolute path of the current working directory.
Rename	Used to rename a file.
Rm	Remove all files or directories.
Rmdir	Remove empty directories to delete empty directories.
Touch	Create a new empty file and change the timestamp attribute of the existing file.
Tree	The function is to display contents in a directory in a tree structure.
Basename	Displays the file name or directory name.
Dirname	Displays the file or directory path.
Chattr	Change the extension attributes of a file.
Lsattr	View the file extension attributes.
File	The type of the displayed file.
Md5sum	Calculate and verify the MD5 value of the file.
View File and content processing commands (21)
Cat	Concatenate is used to connect multiple files and print them to the screen output or redirect them to the specified file.
Tac	Tac is the reverse spelling of cat, so the command function is to reverse display the file content.
More	The file content is displayed by page.
Less	The file content is displayed by page. The more command is used in reverse mode.
Head	Displays the File Content Header.
Tail	The end of the file.
Cut	Splits and outputs each line of the file according to the specified delimiter.
Split	Split the file into different small fragments.
Paste	Merge file content by line.
Sort	Sorts the text content of a file.
Uniq	Remove duplicate rows. Oldboy
Wc	Count the number of lines, words, or bytes of the file.
Iconv	The encoding format of the converted file.
Dos2unix	Converts a DOS file to a UNIX file.
Diff	Difference is used to compare differences between files.
Vimdiff	Command Line visual file comparison tool, commonly used in text files.
Rev	Reverse output file content.
Grep/egrep	Filter string.
Join	Merge by the same fields of the two files.
Tr	Replace or delete characters.
Vi/vim	Command Line Text Editor.
File compression and decompression commands (4)
Tar	Package and compress. Oldboy
Unzip	Decompress the file.
Gzip	Gzip compression tool.
Zip	Compression tool.
Information Display command (11)
Uname	Command Used to display information about the operating system.
Hostname	Displays or sets the Host Name of the current system.
Dmesg	Displays the boot information to diagnose system faults.
Uptime	Displays the system running time and load.
Stat	Displays the status of a file or file system.
Du	Calculate disk space usage.
Df	Reports disk space usage of the file system.
Top	Displays system resource usage in real time.
Free	View the system memory.
Date	Display and set the system time.
Cal	View calendar and other time information.
Search file commands (4)
Which	Find binary commands and search by PATH of the environment variable.
Find	Search for files or directories through disk traversal.
Whereis	Find binary commands and search by PATH of the environment variable.
Locate	Run the/var/lib/mlocate. db command to update the database.
User management commands (10)
Useradd	Add a user.
Usermod	Modify existing user attributes of the system.
Userdel	Delete a user.
Groupadd	Add user groups.
Passwd	Change the user password.
Chage	Change the validity period of the user password.
Id	View the uid, gid, and user group of the user.
Su	Switch user identity.
Mongodo	Edit exclusive commands for the/etc/sudoers file.
Sudo	Execute commands allowed in the sudoers file as another user (Default root User.
Basic network operation commands (11)
Telnet	Use TELNET to log on remotely.
Ssh	Use SSH encryption protocol for remote logon.
Scp	Complete secure copy, used to copy files between different hosts.
Wget	Download the file through the command line.
Ping	Test the network connectivity between hosts.
Route	Displays and sets the route table of a linux system.
Ifconfig	Command for viewing, configuring, enabling, or disabling network interfaces.
Ifup	Start the NIC.
Ifdown	Disable the NIC.
Netstat	View the network status.
Ss	View the network status.
In-depth network operation commands (9)
Nmap	Network scan command.
Lsof	Full name list open files, that is, list files already opened in the system.
Mail	Send and receive emails.
Mutt	Mail management commands.
Nslookup	Interactive Query of Internet DNS commands.
Dig	Find the DNS resolution process.
Host	Query DNS commands.
Traceroute	Tracks the Route status of data transmission.
Tcpdump	Command Line packet capture tool.
Commands for disks and file systems (16)
Mount	Mount the file system.
Umount	Uninstall the file system.
Fsck	Check and fix the Linux File System.
Dd	Convert or copy files.
Dumpe2fs	Export ext2/ext3/ext4 file system information.
Dump	Ext2/3/4 file system backup tool.
Fdisk	Disk Partition command, applicable to disk partitions under 2 TB.
Parted	The disk partition command does not limit the disk size. It is usually used for disks smaller than 2 TB.
Mkfs	Format and create a Linux File System.
Partprobe	Update the information of the hard disk partition table of the kernel.
E2fsck	Check the ext2/ext3/ext4 file system.
Mkswap	Create a Linux swap partition.
Swapon	Enable swap partition.
Swapoff	Disable swap partition.
Sync	Write Data in the memory buffer to the disk.
Resize2fs	Adjust the size of the ext2/ext3/ext4 file system.
System permissions and user authorization commands (4)
Chmod	Change the file or directory permissions.
Chown	Changes the owner and group of files or directories.
Chgrp	Change the file user group.
Umask	Display or set the permission mask.
Command for viewing system user login information (7)
Whoami	A valid user name is displayed, which is equivalent to executing the id-un Command.
Who	Displays the user information of the current logon system.
W	Displays the list of users that have logged on to the system and the commands that the user is executing.
Last	Displays the users logged on to the system.
Lastlog	Displays the last logon information of all users in the system.
Users	Displays the list of all users currently logged on to the system.
Finger	Search for and display user information.
Built-in commands and others (19)
Echo	Print the variable or directly output the specified string
Printf	Format the result and output it to the standard output.
Rpm	Command for managing rpm packages.
Yum	Automate and simplify the command for managing rpm packages.
Watch	Periodically execute the given command and display the command output in full screen mode.
Alias	Set the system alias.
Unalias	Cancels the system alias.
Date	View or set the system time.
Clear	Clear the screen.
History	View the command execution history.
Eject	The optical drive is displayed.
Time	Calculates the command execution time.
Nc	Powerful network tools.
Xargs	Converts a standard input to a command line parameter.
Exec	The command that calls and executes commands.
Export	Set or display environment variables.
Unset	Delete a variable or function.
Type	Used to determine whether another command is a built-in command.
Bc	Command Line scientific calculator
System management and performance monitoring commands (9)
Chkconfig	Manage Linux boot items.
Vmstat	Virtual Memory statistics.
Mpstat	Displays the status statistics of each available CPU.
Iostat	Statistics System IO.
Sar	Obtain performance data of the system, including CPU, Operation queue, disk I/O, paging (SWAP zone), memory, CPU interruption, and network.
Ipcs	Used to report the status of inter-process communication facilities in Linux. The displayed information includes the message list, shared memory, and semaphore information.
Ipcrm	Deletes one or more message queues, semaphore sets, or shared memory IDs.
Strace	Used to diagnose and debug the Linux user space tracker. We use it to monitor the interaction between user space processes and the kernel, such as system calls, signal transmission, and process status changes.
Ltrace	The command will trace the library function call of the process, and it will show which library function is called.
Command for shutdown/restart/logout and Viewing System Information (6)
Shutdown	Shut down.
Halt	Shut down.
Poweroff	Power off.
Logout	Exit the Shell that is currently logged on.
Exit	Exit the Shell that is currently logged on.
Ctrl + d	The shortcut for exiting the currently logged-on Shell.
Process Management commands (15)
Bg	Change a command that is paused in the background to continue (executed in the background ).
Fg	Move the commands in the background to the foreground to continue running.
Jobs	View the number of commands currently running in the background.
Kill	Terminate the process.
Killall	Terminate a process by process name.
Pkill	Terminate a process by process name.
Crontab	Scheduled Task Command.
Ps	Displays the process snapshot.
Pstree	Process is displayed in a tree.
Nice/renice	Adjust the program running priority.
Nohup	Ignore the pending signal and run the specified command.
Pgrep	Find the matching process.
Runlevel	View the current running level of the system.
Init	Switch the running level.
Service	Starts, stops, restarts, and disables system services, and displays the current status of all system services.