Commands for displaying directories and files

   Ls: Commands for viewing all folders .

   Dir: Commands for displaying specified folders and directories    Tree:  List contents in tree view

   Du: Show directory or file size  


Modify directory , File permissions and owner and array commands

   Chmod: Permission command to change the specified directory or file .

   Chown: Commands for changing file ownership properties .

   Chgrp: Commands for changing file groups .

   Chattr: Used to set that files have permissions that cannot be deleted and modified .

   Lsattr: Hidden properties for displaying files or directories .


Commands for creating and deleting directories

   Mkdir: Used to create a directory

   Rmdir: To delete an empty directory

   Rm -f: Used to delete a directory that is not empty


Create and delete , rename , Commands for copying files

  Touch: Create a new file

   Vi: Create a new file

   Rm: Delete file or directory

   Mv: Commands to rename or move files

   Cp: Copy command

   Scp: Used to copy local files or directories to a remote server

   Wget: For download ftp or http Server files to local .


Commands to display the contents of a file

   Cat: Used to display the entire contents of the specified file

   More: Displays the contents of a specified file in pages

   Less: Displays the contents of the specified file in pages , The difference is more and less Different operation keys for page turning .

   Head: Used to display the front of a file n Line content .

   Tail: After used to display files n Line content .

   Tail -f: After display file for automatic refresh n Row data content .


Find command

   Find: Command to find a specified directory or file .

   Whereis: Find the specified file source and binaries, manuals, etc

   Which: Location used to query commands or aliases .

   Locate: Quick search system <>
<> <>
<> data base <> Specified in .

   Grep: In the specified file or standard output , In standard input , Find what meets the criteria .


Commands to shut down and restart the computer


   Shutdown:-r  Restart immediately after shutdown

             -k  Not really shut down , It's just a warning to all users

             -h  Do not restart after shutdown

   Poweroff: For shutdown and power off

   Init: Change system operation level

        0 Level is used to shut down the system

        1  Level for single user mode

        2 Level is used for multi-user usage mode ( But without network function )

        3 Level is used for multi-user usage mode ( With network full function )

        4 Level is used for user-defined usage mode

        5 Level indicates entry x  windows Mode of time

        6 Level is used to restart the system

   Reboot:  For computer restart

   Halt: Used to shut down the computer system


Compression and packaging commands

   Tar: For packaging multiple files or directories , But not compressed , At the same time, unpack with command

   Gzip: Commands for compressing and decompressing files , The file extension is .gz ending .

   Gunzip: For gzip Compress the document for decompression .

   Bzip2: Used to compress and decompress files or directories

   Bzcat: Use to display the contents of a compressed file .

   Compress/un compress:  compress / decompression .Z file

   Zcat: see z or gz Compressed file content at the end .

   Gzexe: Compress executable

   Unarg: decompression .arj file

   Zip/unzip: Compression and decompression .zip file


User operation command

   Su: Toggle user command

   Sudo: A system administrator's identity to execute commands

   Passwd: Password used to modify the user


Change directory and view current directory command

   Cd: get into <>
<> <>
<> work <> catalog

   Cd ..: Back to the next level

   Pwd: Display the working directory location of the current user


File connection command

   Ln: Create a connection for the source file , Do not copy the source file , That is, the occupied space is very small .

        It can be divided into software connection and hard link .

        Soft connection : Also known as symbolic connection , Create a shortcut to a file or directory .

Hard link : Give more than one name to a file , Put it in a different directory , User friendly .


Ln The command parameters are as follows :

   -f: When creating a connection , First delete the file or directory with the same name as the destination object .

   -d: Allow system administrators to hard link their own directories .

   -i: Ask the user before deleting a file or directory with the same name as the destination object .

   -n: When creating a soft connection , Treat the target object as a general document .

   -s: Create a soft connection , I.e. symbolic connection .

   -v: Show file or directory names before connecting .

   -b: Backup files that will be overwritten or deleted when connecting .


Help command -----man

<> other
<> command

   Who: Which users are using in the display system .

        -ami   Show current user

        -u: Show user actions / work

        -s: Use a short format to display

        -v: Show program version

   Free: View the memory usage of the current system

   Uptime: Shows how long the system has been running

   Ps: Show the dynamics of the transient process

   Pstree: Display all processes in the system in tree mode

   Date: Display or set the date and time of the system .

   Last: Display the user information of login system every month

   Kill:  Kill specific processes

   Logout: Exit the system

   Useradd/userdel: Add user / delete user

   Clear: Clear screen

   Passwd: Set user password



vi editor

    First use vi Command to open a file

Last line mode command :

   :n,m w path/filename  Save the specified scope document ( n Table start row ,m Table end row )

   :q!     After modification of the document , forced return

   :q      No changes have been made to the file to exit

   Wq or x   Save exit

   dd   Delete cursor line

   : set number set number

   :n Jump to n That's ok

   :s  Replace string  :s/test/test2/g  /g Global replace / It can also be used % replace

   / Find string


Commands commonly used in network communication

   Arp: Network address display and control

   ftp: file transfer

   Lftp: file transfer

   Mail: send out / Receive email

   Mesg: Allow or deny other users to send information to their own terminals

   Mutt E-mail  Management procedure

   Ncftp : file transfer

   Netstat: Show network connections . Routing table and network interface information

   Pine: outlook express , Browse newsgroups

   Ping: Used to check whether the network is connected smoothly

   Ssh: Remote login in safe mode

   Telnet: Remote login

   Talk: Talk to another user

   Traceroute: Display the path to a host and the time used .

   Wget: Automatically download files from the network
   Write: To others <>
User terminal writes information     Rlogin: Remote login