Summary of 73 commonly used commands in Linux shell

Preface

Using the Linux shell is a basic daily job for some programmers, but we often forget some useful shell commands and techniques. Sure, I can remember the command, but I can't say I can remember how to perform a specific task with it. One thing to note is that some usage requires the installation of additional software in your Linux system. Not much to say below, let’s take a look at the detailed content.

Check whether the remote port is open to bash:

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

Let the process transfer Enter the background:

Ctrl + z

Bring the process to the foreground:

fg

Generate random hex 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

Truncate the first 5 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 grab The complete website directory structure is stored in the local directory:

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

Create multiple directories at once:

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

List including child processes Process tree:

ps axwef

Create war file:

jar -cvf name.war file

Test hard disk writing Speed:

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

Test hard drive Reading speed:

hdparm -Tt /dev/sda

Get md5 hash of text:

echo -n "text" | md5sum

Check xml format:

xmllint --noout file.xml

Extract tar.gz to a new directory:

tar zxvf package .tar.gz -C new_dir

Use curl to get HTTP header information:

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

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

touch -t 0712250000 file

Use wget command to perform ftp download:

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

Generate a random password (16 characters long in the example):

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/share/test/dir

Execute the commands in the history (Here is line 100):

!100

Unzip:

unzip package_name.zip -d dir_name

Enter Multi-line text (CTRL + d to exit):

cat > test.txt

Create an empty file or clear an existing file:

\> test.txt

Synchronize 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

Repeatedly run the file, Display its output (default is every 2 seconds):

watch ps -ef

All user list:

getent passwd

Mount root in read/write mode:

mount -o remount,rw /

Mount a directory (this is the case when links cannot be used):

mount --bind /source /destination

Dynamic update DNS server:

nsupdate <

Recursively 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

Display 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

Git switch to other branch (develop):

git checkout develop

Git delete branch (myfeature):

git branch -d myfeature

Git deletes the 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

Run the last cat command in the history:

!cat

Find all empty subdirectories under /home/user:

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

Get the contents of lines 50-60 in the test.txt file:

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

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

sudo !!

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

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

Grep whole words:

grep -w "name" test.txt

Append text to a file when privileges need to be elevated:

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

List all kill Signal parameter:

kill -l

Disable recording of the last session in bash history:

kill -9 $$

Scan the network for open ports:

nmap -p 8081 172.20.0.0/16

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

will All files containing "txt" in their file names are moved into the /home/user directory:

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

Display files side by side:

paste test.txt test1.txt

Progress bar in shell:

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 spaces:

expand test.txt > test1.txt

Skip bash history:

< space >cmd

Go to the previous working directory:

cd -

Split the large tar.gz files (100MB each) and merge them back:

split –b 100m /path/to/large/archive /path/to/output/files cat files* > archive

Use curl to get HTTP status code:

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

Set root password to strengthen MySQL security installation:

/usr/bin/mysql_secure_installation

When Ctrl + c does not work:

Ctrl + \

Get the file owner:

stat -c %U file.txt

block device list:

lsblk -f

Find files with spaces at the end of their file names:

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

Find the files whose file names have tab indentation

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

Use "=" to print out horizontal lines: select all and copy them into notes

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

Summary

The above is the entire content of this article. I hope the content of this article can bring some help to everyone's study or work. And convenient, if you have any questions, you can leave a message to communicate.

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