Linux Common commands

1. Directory Processing commands

1,ls

① Command English original: list

② Command path:/bin/ls

③ Execute permissions: All Users

④ function Description: Display directory file

⑤ syntax: LS [options] [file or directory]

-A (all) displays all files, including (".") opening) hidden files

- L (long) details display

- D View Directory properties

- h humanized display

-I displays the inode number for each node

-rw-r--r--. 1rootroot 8470 Oct 04:56 Install.log

①-: File Type (-: binary file, D: directory, L: Soft link file)

②rw-r--r--: File permissions (r: Read, W: Write, x: Execute)

Each 3 is a group, the first group: Owner permissions, second group: All group permissions, Group Three: Other people permissions

③ 1: Number of hard links pointing to the file

④root: Owner

⑤root: Owning Group

⑥8470: File Size

⑦oct 15 04:56: Last Modified time

⑧install.log: File name

2,mkdir

① Command English original meaning: make directories

directory where the ② command is located:/bin/mkdir

③ Execute permissions: All Users

⑤ function Description: Create a new directory

④ syntax: mkdir [options] [directory name 1][directory name 2][directory name n]

- P: recursive creation

When no option is added, the directory is not recursively created by default, so the/tmp/test/testmkdir directory cannot be successfully created without/tmp/test the directory exists.

With the-p option, which means that the directory is created recursively, this command recursively creates the/tmp/test directory and/tmp/test/testmkdir directory if no/tmp/test directory exists

mkdir can create multiple directories at the same time, just separate multiple directory names with spaces in the parameters

3.CD

① Command English original meaning: Change directory

directory where the ② command is located: Shell built-in commands

③ Execute permissions: All Users

④ function Description: Switch directory

⑤ Syntax: CD [catalogue]

Cd.. : Represents the switch to the previous level of the current directory

4.pwd

① Command English original: Print working directory

directory where the ② command is located:/bin/pwd

③ Execute permissions: All Users

④ function Description: Show current directory

⑤ Syntax: pwd

5,rmdir

① Command English original meaning: remove empty directories

directory where the ② command is located:/bin/rmdir

③ Execute permissions: All Users

④ function Description: Delete empty directory

⑤ syntax: rmdir [Catalog]

6.CP

① Command English original meaning: copy

② Command path:/BIN/CP

③ Execute permissions: All Users

④ function Description: Copy files or directories

⑤ syntax: CP [option] original file or directory 1[original file or directory 2][original file or directory N] destination directory

- R: Copy Directory

- P: Preserve file attributes

cp: Copy files without the option.

cp-r: Copy Directory

cp-p : Copying files and preserving their file attributes

Copy multiple files at the same time (be sure to specify the destination directory at the end)

Cp/root/anaconda-ks.cfg/root/install.log.syslog/tmp

Copy and modify directory names using Cp-r:

Cp-r/tmp/test/test2/tmp/rename

Copy and modify the file name:

Cp/tmp/install.log/tmp

6,MV

① Command English Intent: move

② Command path:/BIN/MV

③ Execute permissions: All Users

④ function Description: Cut file, rename

⑤ Syntax: MV [original file or directory] [target directory]

* Renaming: Original and target files in the same directory

7,RM

① Command English Original: remove

② Command path:/BIN/RM

③ Execute permissions: All Users

④ syntax: rm-rf [file or directory]

- r Delete directory

- F Force Delete

⑤ function Description: Delete files or directories

2. File Processing command

1.Touch

① Command path:/bin/touch

② Execute permissions: All Users

③ syntax: touch [filename]

④ function Description: Create an empty file

Touch creates multiple files "separated by spaces":

Touch TestToch1 TESTTOUCH2

Touch create file name with spaces "double quotes":

Touch "Program Files"

2.Cat

① Command path:/bin/cat

② Execute permissions: All Users

③ syntax: cat [filename]

④ function Description: Display file contents

-N: Show line numbers

3.TAC

① Command path:/USR/BIN/TAC

② Execute permissions: All Users

③ syntax: TAC [filename]

④ function Description: Display file contents (reverse list)

4, more

① Command path:/bin/more

② Execute permissions: All Users

③ syntax: more [filename]

(space) or F: Page turn

(Enter): line break

Q or Q: Exit

④ Function Description: page displays the contents of the file (cannot page up)

5. Less

① Command path:/usr/bin/less

② Execute permissions: All Users

③ syntax: less [filename]

④ Function Description: page displays the contents of the file (can page up)

(space) or F: Page Down

(Enter): Wrap Down

(PageUp): Page Up

(↑): Line up

/: Find (/+ Find content + "enter")

N: Look down

Q or Q: Exit

6.Head

① Command path:/usr/bin/head

② Execute permissions: All Users

③ syntax: head [filename]

④ function Description: Displays the first few lines of the file

-n Specifies the number of rows (10 rows are displayed by default if the-n parameter is not executed)

7,tail

① Command path:/usr/bin/tail

② Execute permissions: All Users

③ syntax: tail [file name]

④ function Description: Displays the following lines of the file

-N: Specify the number of rows (10 rows By default if the-n parameter is not executed)

-F: Dynamic display of File end content

8,Ln

① Command English original meaning: link

② Command path:/BIN/LN

③ Execute permissions: All Users

④ Syntax: ln [original file] [target file]

-S: Create soft links (do not add parameters to create hard links)

⑤ function Description: Generate link file

3. Rights Management Commands

1,chmod

① Command English Original: Change the permissions mode of a file

② Command path:/bin/chmod

③ Execute permissions: All Users

④ syntax: chmod [{ugoa}{+-=}{rwx}] [file or directory]

[Digital Permissions] [File or directory]

-R Recursive modification

⑤ function Description: Change file or directory permissions

* Only the file or directory "owner" or "root user" can modify the permissions of the current file or directory

*u: Owner, G: Owning group, O: Others, A: everyone

* Digital rights: R (Read): 4,w (Write): 2,x (Execute): 1

Example: chmod 755/tmp/test (File permissions modified to: Rwxr-xr-x)

* Delete this file only if you have write access to the directory where the file is located

2, chown

① Command English Original: Change file ownership

② Command path:/bin/chown

③ Execute permissions: All Users

④ syntax: chown [user] [file or directory]

⑤ function Description: Change the owner of a file or directory

⑥ Example: Chown yonghu/tmp/test (Change the owner of the file/tmp/test to Yonghu)

* Only the root user can change the file owner

* The specified user must be a user present in the system

3,chgrp

① Command English Original: Change file group ownership

② Command path:/BIN/CHGRP

③ Execute permissions: All Users

④ syntax: chgrp [user Group] [file or directory]

⑤ function Description: Change the owning group of a file or directory

⑥ Example: Chgrp yonghuzu/tmp/test (change file/tmp/test belongs to group Yonghuzu)

4,umask

① Command English original: the User file-creation mask

② command path: Shell built-in command

③ Execute permissions: All Users

④ syntax: umask [-S]

-S Displays the new file default permissions in rwx form

⑤ function Description: Display, set default permissions for files

* Use Touch to create a new file with no executable permission (equivalent to the default permission to remove all enforceable permissions)

* Default permissions: U=rwx,g=rx,o=rx, new file permissions: rw-r--r--

* When setting default permissions, set the value to 777 minus the default permission value for the desired setting

* Default permissions you want to set: U=rwx,g=rx,o=r (754) "777-754=023"

* Execution command: umask 023

"No Modification recommended"

4. File Search command

1.Find

① file path:/bin/find

② Execute permissions: All Users

③ syntax: Find [Search Range] [match condition]

④ function Description: File search

⑤ Common options:

-name: Search by file name (-iname not case-sensitive) "Wildcard characters supported"

"*": matches any character

Example: Find/etc-name *init*

”?“ : Matches a single character

Example: Find/etc-name init???

-size: Search by File size (unit: Data block "1 database =0.5k")

+n: Greater Than

-N: Less than

N: Equals

Example: Find/-size +204800 (find files larger than 100M)

-user: Search by Owner

-group: Search by owning group

-type: Search by file type

F: File

D: Catalogue

L: Soft Connection file

-inum: Search by I node

-exec/-ok command {} \; : Performing actions on search results

Search by Time attribute:

-amin Access Events (Access)

-cmin file attributes (change)

-mmin file contents (odify)

+n:n minutes or more

Within-n:n minutes

Example: Find/etc-cmin-5 (Find files and directories with properties modified within 5 minutes in/etc)

Connection properties:

-A: two conditions simultaneously satisfy

-O: Two conditions to satisfy any one

Example: Find/etc-size +163840-a-size-204800 (find files larger than 80MB less than 100MB in/etc)

2,locate

① Command path:/usr/bin/locate

② Execute permissions: All Users

③ Syntax: Locate file name

④ function Description: Find files in the file repository

UpdateDB: Update file repository (files in/TMP are not included in the file repository)

3,which

① Command path:/usr/bin/which

② Execute permissions: All Users

③ syntax: which command

④ function Description: Search the directory of the command and alias information

4,Whereis

① Command path:/usr/bin/whereis

② Execute permissions: All Users

③ syntax: whereis [command name]

④ function Description: Search command directory and help document path

5.grep

① Command path:/bin/grep

② Execute permissions: All Users

③ syntax: grep [Specify string] [file]

④ function Description: Search the file for string matching lines and output

-I: Case insensitive

-V: Excludes specified strings

5. Help command

1, man

① Command English original meaning: manual

② Command path:/usr/bin/man

③ Execute permissions: All Users

④ syntax: Man [command or config file]

⑤ function Description: Get help information

You do not need to fill in the absolute path when viewing the configuration file, only the file name

2,Whatis

① Syntax: Whatis command

② function Description: View command Brief information

3,apropos

① syntax: Apropos configuration file name

② function Description: View cut SMS for profile

4,--help

① Syntax: Command--help

② function Description: Get help information for the command

5. Help

① command path: Shell built-in command

② Execute permissions: All Users

③ Syntax: Help command

④ function Description: Get help for Shell built-in commands

6. User Management commands

1,Useradd

① Command path:/use/bin/useradd

② Execute permissions: root

③ syntax: Useradd user name

④ function Description: Add new user

2,passwd

① Command path:/usr/bin/passwd

② Execute permissions: All Users

③ syntax: passwd user name

④ function Description: Set User password

Ordinary users can only modify their own password, the root user may modify all user's password

3. who

① Command path:/usr/bin/who

② Execute permissions: All Users

③ syntax: WHO

④ function Description: View logged in user information

4,W

① Command path:/usr/bin/w

② Execute permissions: All Users

③ Syntax: w

④ function Description: View logged in user details

7, Compression decompression command

1.gzip

① Command English original: GUN zip

② Command path:/bin/gzip

③ Execute permissions: All Users

④ syntax: gzip [file]

-D: Uncompressed (equivalent to gunzip)

⑤ function Description: Compress file

⑥ compressed file format:. gz

* Only files are compressed and source files are not preserved

2,gunzip

① Command English original: GUN unzip

② Command path:/bin/gunzip

③ Execute permissions: All Users

④ syntax: gunzip [Compressed file]

⑤ function Description: Unzip the. GZ zip file

3.Tar

① Command path:/bin/tar

② Execute permissions: All Users

③ Syntax:

Ⅰ: Packaging compression

Tar options [-ZCF] [file name after compression] [directory]

-C: Packaging

-V: Show more information

-F: Specify file name

-Z: Pack and Compress ". tar.gz"

-j: Pack and Compress ". Tar. BZ2 "

Ⅱ: Decompression

Tar options [-ZXVF] [Compressed Files]

-X: Unpacking

-V: Show more information

-F: Specifying Compressed Files

-Z: Unzip ". tar.gz"

-j: Unzip ". tar.bz2"

④ function Description: Package, compress, unzip directory

3.Zip

① Command path:/usr/bin/zip

② Execute permissions: All Users

③ syntax: Zip option [-r] [filename compressed] [file or directory]

-R: Compressed directory

④ function Description: Compress files or directories

⑤ compressed file format:. zip

4,unzip

① Command path:/usr/bin/unzip

② Execute permissions: All Users

③ syntax: Unzip [compressed file]

④ function Description: Unzip the. zip file

5,bzip2

① Command path:/USR/BIN/BZIP2

② Execute permissions: All Users

③ syntax: bzip2 option [-K] [file]

-K: Preserves source files after generating compressed files

④ function Description: Compress file

⑤ compressed file format:. bz2

6,bunzip2

① Command path:/USR/BIN/BUNZIP2

② Execute permissions: All Users

③ syntax: BUNZIP2 option [-K] [compressed file]

-K: Preserves source files after decompression

④ function Description: Unzip the. bz2 compressed file

Linux Common commands