LinuxCommands.md

to clear the Command line screen

clear

to create the new directory

mkdir (directory_name)

using this command we can create directoty DN2 inside the directory DN1 using single command

mkdir -p DN1/DN2

to create multiple directiory DN1 DN2 DN3 using single command

mkdir DN1 DN2 DN3

to create new file

touch (file_name)

to create multiple files FN1 FN2 FN3 using single command

touch FN1 FN2 FN3

to view the list of files or directories

ls

to view the list of files or directories in the long format (permission, date , time)

ls -l

to view the list of files or directories in the long format in ascending order (A-Z, It shows lateste modified files or directories at the bottom)

ls -lrt

to view the list of files or directories in the long format in descending order (Z-A, It shows lateste modified files or directories at the top)

ls -lt

to view the files/directories inside the directoies

ls -l FN/DN

change directory

cd

to come out from the previous directory

cd ..

to come out from the previous directory

cd -

to come out from the previous two directories

cd ../..

to go inside the DN directory

cd DN

to go inside the DN2 directory which is present in DN1 directory

cd DN1/DN2

It shows present working directory

pwd

to print the file data in terminal

cat FN

to print the file data with serial number in terminal

cat -n FN

to print the statement in the terminal

echo "Text"

to print the data in two lines in the terminal

echo -e "Text1\nText2"

to save the data in file

echo "File Data" > FN

to get the history of the terminal

history

to print the first 10 lines of the file data in the terminal

head FN

to print the first n number of lines of the file data in the terminal

head -n (no.of lines) FN

to print the last 10 lines of the file data in the terminal

tail FN

to print the last n number of lines of the file data in the terminal

tail -n (no.of lines) FN

to exit from user account

exit

to update the package in Ubuntu

apt update

to install the required package in Ubuntu

apt install (package_name)

to copy all the files and folders to other location

navigate to the folder where all the files and folders inside that folder to be copied to another location

cp -r * /path_of_location

to rename directory

mv old_directoty_name new_directory_name

to find the any directory or file name

find / -name jvm

find / -name java-11*

To get the public key of the EC2 Insatnce

cd ~/.ssh

To create a symbolic link

ln -s Original_path path_where_link_to_be_created

To delete file

rm file_name

To copy all the files and folders from present directory to one step above directory

cp -r * ../directory_name/

To check the users

cat /etc/passwd

To check the groups

cat /etc/group

To create user

useradd user_name

To add passwd to user

passwd user_name

To add user to group

usermod -aG group_name user_name

enable password authentication for ec2 instance

vi /etc/ssh/sshd_config

reload sshd

service sshd reload

Recursively and Force removal of files or directories.

rm -rf directory_name/

give permission of the directory to user

chown -R user_name:user_name directory_name

move the file

mv file_name directory_path

change the hostname

vi etc/hostname

reboot

init 6

add user to sudoer

visudo

switch to user

sudo su - user_name

become root user

sudo su -

find the matching word in file

grep word_search path/

untar file

tar xvzf tar_file

check user group

id user_name

add sudo access to ec2-user

echo "ec2-user All=(All) NOPASSWD:ALL" >> /etc/sudoers