Linux Common Commands Summary

Linux Common Commands Summary

1. Display date and time: Date

Can modify the display date format, such as: Date +%y/%m/%d%h:%mà2016/12/25 17:05 (%Y: Year;%m: month;%d: day;%h:24 hour system;%m: Min.)

Date–d parameters can add: Today/yesterday/tomorrow to display today, yesterday, tomorrow's date

2. Display Calendar: Cal (this month's monthly calendar is displayed by default)

Cal 2001 displays a 2001 year calendar; Cal 10 2001 can display a month calendar in detail

3. Calculator: BC

4, Tab: Used in the command after the completion of commands, use the directory or file after the name of the files to fill

5. Shutdown/Restart command

Shutdown–h now: Shut down immediately

Shutdown–h +10 ' The system would shutdown ': Shut down and give hints after 10 minutes

Shutdown–h 22:20: Determine actual shutdown

Shutdown–r Now: Restart immediately

Shutdown–r +10 ' The system would reboot ': Restart after 10 minutes and send messages to all online users

Other common commands: reboot: System restart; Poweroff: System shutdown; Init 0: System shutdown

6, File system simple operation

DF: List The overall disk usage of the file system (–h in a convenient-to-read format)

Du: List all file sizes in the current directory (–s, show only the size of this directory)

7. User Management

(1) User

New User: Useradd [–u UID] [–g Settings Group] [–c description] [–d Settings Home directory (if you do not set the default in/home directory)];

Set Password: passwd username (password has been set to change the password, ordinary users can modify their own password, the root user can change the password of everyone);

Modify user information: Usermod the directive option is similar to Useradd and can be modified by the corresponding option;

Delete User: Userdel username (username–r username: deleted together with User home directory)

(2) Group

New group: Groupadd groupname

Create group password: gpasswd groupname

Modify Group: Groupmod groupname

Delete Group: Groupdel groupname

(3) Query user information

Finger Username: Query A user related account attributes;

Finger: Query login user and login time on current system

ID: Query your own ID information

ID Username: Querying for a user ID information

W, who: Query the current system is logged on users

(4) User identity switch

SU: direct identity switch without changing environment variables

su–: Switch user identity while reloading user's environment variables, complete switch to new user's environment

Exit: Current User exits

sudo command: Get superuser privileges to execute command (use sudo instruction to set value in/etc/sudoers file, add username all= (All))

8. Directory/File operation

(1) directory switch CD:. current directory;. Previous directory;-Previous working directory; ~ Current user's home directory

(2) PWD: Displays the current path

(3) mkdir: Create a new directory (MKDIR–P/HOME/AAA/BBB/CCC a multi-level directory at a time)

(4) RmDir: Delete an empty directory (RMDIR–P/HOME/AAA/BBB/CCC delete multiple empty directories at once)

(5) RM–R/HOME/AAA: Delete multiple layers of non-empty directories, recursively delete

(6) View catalog contents Ls:–a display all files, including hidden files (files named after.); –l Long data string display, including file attributes and permissions information; –d list only directories, directory internal files are not listed;

(7) Copy operation cp– option source destination

–i: If the destination file already exists in the copy, ask whether to overwrite

–f: Force copy, do not ask

–s: Copy as Soft link (shortcut), point to target file, cannot open if target file is deleted

–l: Copy as Hard link

–r: Recursive replication

(8) Move/rename mv– option source destination

(9) Modify operation permissions chmod, including file owner O, file with Group G, other people rights u, all a

chmod 740 FileName: Digitally modified, read-4, write-2, execute-1

chmod u+x FileName: Modified by letter, read-R, write-W, execute-X, add permission with "+", remove permission with "–"

Chmod–r u+x dirname\*: All file modification permissions in the directory

(10) Modify the file owner Chown; Modify the owning group of the file Chgrp

(11) Create an empty document touch

(12) View the contents of the document: command file name

Cat: Displays the contents of the document starting at the first line; TAC: Starting from the last line (adding line numbers when the option-n is displayed)

MORE: Page by page, back page; Less: one page, one page, flip ahead

Head–n N: see only the first n rows; tail–n N: Only look at the last n rows; tail–f: Dynamically View the contents of a file

(13) Find files

Which command: Find the execution file, which displays the location of the document where the Find command is located

Whereis Filename/dirname: Shows where a file or directory is located

Locate Filename/dirname:–i can be ignored case –r can be connected to the regular, after you can enter part of the document name for fuzzy query

Find [PATH] [option] [action]:–name Query file name (available regular, fuzzy query); –size indicates file size; –type indicates file type; –perm indicates file permissions; –exec command {}\; Additional actions to be made

9, Compression and packaging

(1) gzip [–cdtv#] FileName: Build a compressed file with the suffix *.gz

–C: outputting compressed data to the screen

–d: Decompression

–t: Checking for compressed file consistency

–v: Displays the compression ratio information for the source document and the compressed document

–#: Compression level, 1 fastest, 9 slowest, default-6

(2) bzip2 [–cdkzv#] FileName: Creating a compressed file with the suffix *.bz2

–k: Preserves source files, does not delete original documents

–z: Compression parameters

–d: Extracting parameters

(3) Packaging and compressing tar

TAR–JCVF filename.tar.bz2 (destination) filename/dirname (source): Compressed in bzip2 mode

TAR–ZCVF filename.tar.gz (destination) filename/dirname (source): Compressed in gzip

TAR–JTVF filename.tar.bz2: Querying Compressed files

TAR–JXVF filename.tar.bz2–c to extract directory: Decompression (bzip2 mode compression)

TAR–ZXVF filename.tar.gz–c to extract directory: Unzip (gzip compression)

10, VI Editor

(1) General mode: VI Open after the direct entry mode, in this mode can move the cursor up and down, you can delete characters, dd delete positive line, yy copy, p paste processing document content;

X: Delete one character backwards; x: delete one character forward;

DD: Delete the current line; NDD: Deletes the current row down n rows; d1g: Deletes the cursor to the first line; DG: Deletes the cursor to the last line;

YY: Copy the current line; Nyy: Copy the current down n line; y1g: Copy cursor to the first line; YG: Copy cursor to last row

P: Paste

U: Undo the previous action, that is, cancel the operation

Ctrl+r: Repeat the previous action (also available as a decimal point operation)

(2) Edit mode: In general mode, press [I, I, O, O, A, a] to enter, press the ESC key to exit the mode;

H: Move one character to the left; J: Move down one character; K: move one character up; L: Move one character to the right;

0: Move to the beginning of the current line; $: Move to the end of the current line line

(3) Command mode: In general mode, enter [:,? ,/] into the command mode, you can query, character substitution, set line number and other operations;

/word: Cursor down query word;?word: Cursor up query word;n: Repeat the previous search action, search down; N: Repeat the previous search action, search upward;

: n1,n2s/word1/word2/g: Find word1 between line N1 and N2, and replace with Word2;

: 1, $s/word1/word2/g: look for word1 between line 1th and last line, and replace with Word2;

Set Nu: Display line number; Set Nonu: Suppress line number

N1,N2 w FileName: Stores the contents of N1 to N2 rows into the filename document

Wq save exit; q! do not save forced exit; wq! Force Save exit

11. Variable-related commands

ENV: View environment variables in the current shell environment;

Set: Displays all variables, including environment variables;

Export: Custom variable to environment variable;

echo $ variable Name: Displays variable contents;

Read variable name: Assign keyboard input to variable

Source profile Name: After modifying the configuration file, execute the source command after setting to take effect

12. Command Aliases Alias

Displays all current command aliases; alias xxx= ' comand ': set command alias; Unalias XXX: Cancels command aliases; works only in the current shell

13. Historical Order History

Displays all the history commands in memory, default to 1000, and historical N: Shows the most recent n executed commands;! N (Command number) executes the nth instruction in history

14. Wildcards and special characters

(1) wildcard characters

*: matches 0 to infinity any number of characters;

?: Match 1 To infinity of any number of characters;

[]: Match any character in parentheses, such as [ABCD] refers to a character in the matching ABCD;

[-]: matches all characters in the range of numbers or letters in parentheses, such as [0-9] refers to all numbers that match 0 to 9;

[^]: the first character in parentheses is a ^ to reverse, such as [^ABC] refers to non-A, B, c of other characters;

(2) Special symbols

#: Comment Information

\: Restore special characters as general characters

|: Pipeline Command

: Redirect (overlay);>> heavy-weighted orientation

"": double quotes with variable substitution function

Cmd;cmd: Multiple commands can be entered consecutively with a semicolon interval

CMD1 && cmd2:cmd1 Correct, execute CMD2;CMD1 error, do not execute CMD2

cmd1 | | Cmd2:cmd1 correct, do not perform CMD2;CMD1 error, execute CMD2

15. Pipeline Command

(1) Data interception: Cut, general usage [cmd | cut–d ' delimiter ' –f N]: Intercepts the output of the previous command with a delimiter and displays the nth field

(2) Line interception: grep, general usage [cmd | grep–a/c/i/n/v ' search string '] or [grep–a/c/i/n/v ' search string ' filename]: Find a string from a command result, or look up a string from a file to display an entire row

(3) Sort: sort,–r reverse sort; –u the same data displays only one row, –t the delimiter, and –k the interval separated by a delimiter to sort between intervals

(4) Count: Wc,–l display the number of lines; –w display word count, English word; –m display characters

(5) Tee filename: Generally used between two pipelines [cmd1 | tee filename| CMD2], the output of the previous command is entered into the specified file, and output to the screen using the following command

16. Scheduled Task crontab

(1) crontab command

Crontab–e: Enter vi edit screen to edit crontab work content,: Wq save exit;

Crontab–l: View the working contents of the set crontab;

Crontab–r: Delete all the crontab work;

(2) Timing settings

The five time periods were: 0-59 minutes, 0-23 hours, 1-31 days, 1-December, 0-7 weeks (0, 7 for Sunday);

* Asterisk: Represents any moment, such as: [* * * * * cmd];

, comma: Represents the separation time period, for example: 3 points per day, 6 points two point-in-time execution instruction [0 3,6 * * * cmd];

– minus: Represents a period of time, such as: daily from 3 o'clock to 6 two time range execution instruction [0 3-6 * * * cmd];

/n slash: Represents every n time unit, such as: Execute [*/5 * * * * cmd] every 5 minutes;

(3) System timing Task settings:/etc/crontab file add crontab directive

17. Program-related commands

(1) View all program data of the system: PS aux

(2) View your bash-related programs only: Ps–l

(3) Dynamic viewing program changes: Top–d 2 (Refresh every 2 seconds)

(4) Termination procedure: Kill PID (The PID of the PS aux query program can be used first)

(5) Termination procedure: Killall [–iei] cmd name (followed by full instruction name)

18. View system resources

Free to view memory usage; Uname–a View system basic information, uptime display system on how long, NETSAT–TLNP display system has been listening to network connection and its PID

19. Software Installation Yum

(1) Format: [option] [Query work items] [related parameters]

(2) –y: Automatically provide yes corresponding

(3) Search: Search for a software

(4) List/info: Lists all software names and versions currently managed by Yum

(5) Install: installation; Update upgrade; remove Delete

Linux Common Commands Summary