Linux commands-linux File and permission management commands-linux permission management

Linux commands-linux File and permission management commands-linux permission management

1. ubuntu tips:

In ubuntu, you can press ctrl + alt + t to open the terminal, and press ctrl + shift + t to open the second terminal.

Adjust the font in ubuntu terminal

Font increase: ctrl + shift + plus sign

Reduce Font: ctrl + minus sign

After entering the vi/vim Editor, enter: set number in command line mode to display the travel number in text.

: Set nonumber

The colors of files, folders, compressed files, and executable programs in ubuntu are different.

If the file name is long, you can press the table key to automatically complete the file.

Press ctrl z or ctrl c to terminate the program being executed.

There are three network connection methods in ubuntu: NAT bridging is only applicable to hosts.

2. linux File and permission management commands:

Clear: clear screen

View help documentation: 1. -- help such as ls -- help

2. man For example: man ls (abbreviation of manual)

History: View historical history-c deletion history

Switch the supermanager permission: After sudo-s, enter the root user

Execute the file as Administrator: su xxx

Root User Switch back to normal user input exit

Root User Password: sudo passwd root

Ls: displays all files and folders in the current path.

Ls-l lists detailed information, ls-lh shows the file size, and ls-lha shows hidden files.

Wildcard

* All characters in the file name

Ls AB * search for files starting with AB ls x *. c list all files with x Headers

Ls *. html search end with the html file ls *. py ls *. c to list all. py. c files.

? Represents any character in the file

Ls ?. C is used to search for any file with the first character and suffix. c.

Ls .? It can only contain three characters. The first two characters are a, and the last character is any file.

[] Enclose character groups to match any one of the character groups. -Used to indicate the character range

[Abc] matches any one of abc

[A-f] matches any character from the-f range

Ls [a-f] * searches for files starting with any character in the-f range

Ls a-f: searches for a file named a-f. If-is out of square brackets, the wildcard is lost.

Ls \ * a find the file named * a \ is an escape character

Touch creates a file

Touch 1.c touch 1.py

> Output redirection command

Linux can redirect the command execution result to a file, and the content displayed on the terminal should be saved to the specified file.

Ls> test.txt is created if it does not exist. If it exists, it overwrites its content.

More split-screen display

When there is too much information, use the more command to view only one page at a time. The space will display the next page, q will exit, and h will help

| Pipeline: the output of one command can be output by pipeline as another command

| It can be divided into left and right ends, left ends, and right ends.

Ls-alh | more

Cd: Jump command

Cd ~ Switch to the current user's home directory

Cd... switch to the parent directory

Cd-returns the last path

Pwd: view the current path

Mkdir: Creates directories and folders.

Mkdir apple: Create an apple folder

 

Rmdir: delete a directory

You can use the rmdir command to delete a directory. The directory must be left and the exposed directory must be empty. Otherwise, the deletion fails.

Rm: delete an object

Rm 123.py Delete common files

Rm apple-r Delete recursive folder

Rm apple-f force delete file

Rm apple-I execution in interactive mode

Ln: create a link file

Link: soft connection: no disk occupation. If the source file is deleted, the soft link becomes invalid.

Hard connection: hard links can only link common files, but cannot link directories.

Ln source file

Ln-s source file link file

If the source file in the soft link is deleted, the link created later becomes invalid.

In a hard connection, the content of a file contains multiple file names and will not be lost due to the deletion of the file name.

 

Cat displays information in the file

Cat 1.c cat 1.txt

Cat and redirection can merge multiple files

Cat 1.txt aaaaa

Cat 2.txt content bbbbb

Cat 1.txt 2.txt> 3.txt aaaaa

Bbbbb

> The output redirection overwrites the original content.

> The output redirection is appended to the end of the file.

Also available

Cat 1.txt> a.txt

Cat 2.txt> a.txt

Then a.txt displays 1.txtand 2.txt.

Grep: Text Search

In linux, The grep command is a powerful text search tool. grep allows mode searches for text files, and grep prints all lines in the contain mode.

General grep format:

Grep [-Option] 'search string' file name

Grep 'A' 1.txt

Common options:

Grep 'xxx' B. py

Grep-n 'xx' B. py shows the number of rows

Grep-n '^ xx' B. py displays the fields that can be found starting with xx.

Grep-n 'xx $ 'B. py displays the fields that can be found at the end of xx.

Grep-n '[Hh] ell [Oo]' B. py search for included Fields

Find: find Files

Find./-name xx. sh find all files named xx in the current directory

Find./-name '*. Sh' find all files with the suffix. sh in the current directory.

Find./-name "[A-Z] *" find all files starting with an uppercase letter in the current directory

Find/tmp-size 2 M search for files equal to 2 MB in the current directory

Find/tmp size + 2 M find files larger than 2 MB in the current directory

Find/tmp size-2 M find files smaller than 2 MB in the current directory

Find./-size + 4 k-size-5 m search for files larger than 4 k and smaller than 5 MB in the current directory

Find./-perm 0777

Cp: copy a file or document directory

Cp 123.py apple/copy 123. py to the apple folder

Cp apple orange/-r recursively copy files in the folder to another folder

Tree/xxxx/display the current or xxx path

Mv: Move a file

Mv file1 file2 will

You can also modify the file name.

Mv 123.py 1234.py

Mv 1234.py 321.py

Tar: Archive Management Package

Format: tar [parameter] package file name

Packaging command: tar-c xxx.tar

Command: tar-x xxx.tar

Tar-cvf test.tar 1.txt 2.txt 3.txt

Tar-cvf a.tar *. py pack all py files

Tar-xvf xxx.tar unpack xxx package

Gzip: A. GZ file generated after File compression

Tar and gzip commands can be used together to package and compress files to generate extension names for xxx.tar.gz

Gzip format

Gzip [Option] compressed file gzip-d decompress

Gzip-r: compress all subdirectories gzip-r test.tar test.tar.gz

Compressed: tar-zcvf test.tar.gz 1.c 2.c 3.c

Decompress: tar-zxvf test.tar.gz

Decompress the package to the specified directory:-C tar-xvf xxx.tar.gz-C./mmmm/decompress it to the mmmm path

Bzip2: File compression to generate bz2 files

Use the extension name with the tar command is generally the xxx.tar.bz2 file.

Add an option in the tar command-j. Call bzip2 to implement the compression function.

Compression usage: tar jcvf xxx.tar.bz2 *. c

Decompress: tar jxvf xxx.tar.bz2

Zip: File compression and unzip

Compressed file: zip [-r] The source file of the target file (No extended name). zip: apple *.*

Decompress the file: unzip-d. decompress the file directory and compress the file unzip-d apple.zip.

Which: view the command location

Which ls: locate the ls directory

3. linux system management commands

Cal: view the current calendar-y displays the calendar of the entire year

Date: display or set the time

Modify system time date [MMDDhhnn [[cc] YY] [. SS] + format

For example, if cc is set to year, YY indicates year, And MM indicates month DD indicates day hh indicates hour nn indicates minute ss indicates second.

Date 010203042018.25

Ps: View Process Information

Ps displays the processes run by the current system. A process is called a program before it is run.

Ps-aux

To terminate a process, enter ps-aux on the second terminal to find the pid of the process.

Top: dynamically displays the resource usage of processes

Input "top" and "M" as memory usage P as cpu usage T as running duration U user name filtering K According to pid killing process q exit h help

Kill: Terminate the process

Use with ps commands

Format: kill [-signal] pid kill 1827

Add the parameter-9 to force the process to end

Kill-9 1827 force Process Termination

Reboot, shutdown, init shutdown and restart

Reboot restart

Shutdown-r now reboot operating system prompt

Shutdown-h now shut down immediately

Shutdown-h shutdown at today

Shutdown-h + 10 minutes later shutdown

Init 0 Shutdown

Init 6 restart

Df: disk space detection

Df command is used to check disk space usage and free space of the file system. df-lh df-m is displayed in 1024 bytes.

Du: disk space occupied by the detection directory

The du command is used to measure the disk space occupied by a directory or file. The result focuses on the disk usage.

The format of the du command is as follows: du [Option] directory or file name du-alh

Ifconfig: view or configure Nic Information

Ping: Test Remote Host connectivity

Ping general rules can communicate with ping 10.222.1.34

4. user permission management commands in linux

Ctrl + alt + (F1-F6) character Interface

Ctrl + alt + F7 exit character Interface

Ctrl + alt find the mouse

Whoami view current user name

Who-q view users

Ssh remote login

After ping, log on to another computer using the ssh command.

Format: ssh username @ IP address exit

Useradd: Add a user account

Switch to supermanager mode in unix/linux and add user accounts

Useradd xxx

Paswd xxx

Switch user su-xxxx exit to exit

Cat/etc/passwd view current user name of the system

Useradd xxxx-m

Passwd: Set the User Password

Userdel xxx: User Deletion

Userdel-r xxx deletes the user directory

Su: Switch users

Switch the Administrator in a non-ubuntu environment, such as in redhat.

Use su root

Su xxx logs in to the original path

Log on to the working directory of su-xxx.

View the number of users

Cat/etc/group or groupmod + three-way tab key

Groupadd abc Add User abc Group

Groupdel abc delete user group abc account

Usermod: Modify the user group

Usermod-g user group Username

Groups xxx

Cat/etc/group | grep 'sudo' from The sudo User group

Add sudo permission

Sudo usermod-a-G adm User Name

Chmod: Modify file permissions

Two methods are available for chmod permission modification.

Ten-rwx

1st-indicates that the file is a normal file.

U and 3 are file owner permissions g and 3 are the permissions of the file owner in the same group. o is the permissions of others.

Chmod u/g/o + r/w/x chmod u + x 1.py add executable permissions to 1. py

Digital method, privilege, R-4, W-2, x-1

Chmod 777 xx. py gives xx. py full Permissions

Chmod u-x 1.py delete executable permissions of the file owner in 1. py

Chown: Modify the file owner

Chown user name file or directory

Chown xxx 1.py

Chgrp: Modify the group to which the file belongs

Chgrp user group name file name chgrp root 1.txt