Summary of 73 commonly used Linux shell commands

For friends who often use linux systems, the basic common shell commands are indispensable. the following article summarizes the commonly used commands of Linuxshell. if you need them, you can refer to them for reference, let's study together. Preface

Using Linux shell is a basic task for some programmers every day, but we often forget some useful shell commands and techniques. Of course, I can remember commands, but I can't remember how to use them to execute a specific task. Note that you need to install additional software in your Linux system. I will not talk about it much below. let's take a look at the details.

Check whether the remote port is open to bash:

Echo>/dev/tcp/8.8.8.8/53 & echo "open"

Transfer the process to the background:

Ctrl + z

Switch the process to the foreground:

Fg

Generate a random hexadecimal number, where n is the number of characters:

Openssl rand-hex n

Execute the command in a file in the current shell:

Source/home/user/file. name

Extract the first five characters:

$ {Variable: 0: 5}

SSH debug mode:

Ssh-vvv user @ ip_address

SSH with pem key:

Ssh user @ ip_address-I key. pem

Use wget to capture the complete website directory structure and store it in the local directory:

Wget-r -- no-parent -- reject "index.html *" http: // hostname/-P/home/user/dirs

Create multiple directories at a time:

Mkdir-p/home/user/{test, test1, test2}

List the process trees that contain sub-processes:

Ps axwef

Create a war File:

Jar-cvf name. war file

Test hard disk write speed:

Dd if =/dev/zero of =/tmp/output. img bs = 8 k count = 256 k; rm-rf/tmp/output. img

Test hard disk read speed:

Hdparm-Tt/dev/sda

Obtain the md5 hash of text:

Echo-n "text" | md5sum

Check xml format:

Xmllint -- noout file. xml

Extract tar.gz to the new directory:

Tar zxvf package.tar.gz-C new_dir

Use curl to obtain HTTP header information:

Curl-I http://www.example.com

Modify the timestamp of a file or directory (YYMMDDhhmm ):

Touch-t 0712250000 file

Run the wget command to download ftp:

Wget-m ftp: // username: password @ hostname

Generate a random password (in this example, it is 16 characters long ):

LANG = c </dev/urandom tr-dc _ A-Z-a-z-0-9 | head-c $ {1:-16}; echo;

Quickly back up a file:

Cp some_file_name {,. bkp}

Access the Windows shared directory:

Smbclient-U "DOMAIN \ user" // dc.domain.com/#/test/dir

Execute the commands in the history (here is the 100th Line ):

! 100

Decompress:

Unzip package_name.zip-d dir_name

Enter multiple lines of text (CTRL + d to exit ):

Cat> test.txt

Create an empty file or clear an existing file:

\> Test.txt

Synchronization time with Ubuntu NTP server:

Ntpdate ntp.ubuntu.com

Use netstat to display all tcp4 listening ports:

Netstat-lnt4 | awk '{print $4}' | cut-f2-d: | grep-o '[0-9] *'

Qcow2 image file conversion:

Qemu-img convert-f qcow2-O raw precise-server-cloudimg-amd64-disk1.img \ precise-server-cloudimg-amd64-disk1.raw

Run the file repeatedly and display its output (the default value is 2 seconds ):

Watch ps-ef

List of all users:

Getent passwd

Mount root in read/write mode:

Mount-o remount, rw/

Mount a directory (this is the case where the link cannot be used ):

Mount -- bind/source/destination

Dynamically update the DNS server:

Nsupdate <

Recursive grep all directories:

Grep-r "some_text"/path/to/dir

List the top 10 largest files:

Lsof/| awk '{if ($7> 1048576) print $7/1048576 "MB" $9}' | sort-n-u | tail

Show remaining memory (MB ):

Free-m | grep cache | awk '/[0-9]/{print $4 "MB "}'

Open Vim and jump to the end of the file:

Vim + some_file_name

Git clone the specified branch (master ):

Git clone git@github.com: name/app. git-B master

Switch Git to another branch (develop ):

Git checkout develop

Myfeature ):

Git branch-d myfeature

Git deletes a remote branch

Git push origin: branchName

Git pushes the new branch to the remote server:

Git push-u origin mynewfeature

Print the last cat command in the history:

! Cat: p

The last cat command in the running history:

! Cat

Find all empty sub-directories under/home/user:

Find/home/user-maxdepth 1-type d-empty

Line 50-60 in the test.txt file:

<Test.txt sed-n '50, 60p'

Run The Last Command (if the last command is mkdir/root/test, run: sudo mkdir/root/test ):

Sudo !!

Create a temporary RAM file system-ramdisk (first create the/tmpram directory ):

Mount-t tmpfs/tmpram-o size = 512 m

Grep whole words:

Grep-w "name" test.txt

Append the text to a file when you need to escalate permissions:

Echo "some text" | sudo tee-a/path/file

List all kill signal parameters:

Kill-l

Do not record the last session in the bash history:

Kill-9 $

Scan the network to find open ports:

Nmap-p 8081 172.255.0.0/16

Set git email:

Git config-global user. email "me@example.com"

To sync with master if you have unpublished commits:

Git pull -- rebase origin master

Move all files whose names contain "txt" to the/home/user directory:

Find-iname "* txt *"-exec mv-v {}/home/user \;

Display files in parallel by row:

Paste test.txt test1.txt

Shell progress bar:

Pv data. log

Use netcat to send data to Graphite server:

Echo "hosts. sampleHost 10 'date + % s" '| nc 192.168.200.2 3000

Convert tabs to a space:

Expand test.txt> test1.txt

Skip bash history:

<Space> cmd

Go to the previous working directory:

Cd-

Split the tar.gz File (100 MB each) and merge it back:

Split-B 100 m/path/to/large/archive/path/to/output/files cat files *> archive

Use curl to obtain the HTTP status code:

Curl-sL-w "% {http_code} \ n" www.example.com-o/dev/null

Set the root password to enhance the secure installation of MySQL:

/Usr/bin/mysql_secure_installation

When Ctrl + c is not easy to use:

Ctrl + \

Get the file owner:

Stat-c % U file.txt

Block device list:

Lsblk-f

Find the file with spaces at the end of the file name:

Find.-type f-exec egrep-l "+ $ "{}\;

Find the file with tab indentions in the file name.

Find.-type f-exec egrep-l $ '\ t '{}\;

Print the horizontal line with "=": Select all copies and put them into notes.

Printf '% 100s \ n' | tr'' =

Summary

The above is all the content of this article. I hope the content of this article will help you in your study or work. if you have any questions, please leave a message.

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