ubuntu - linux basic commands

LINUX BASIC COMMANDS:

change file/folder permission with chmod command:
	-add execute permission to group:
		sudo chmod g+x test.txt
	-remove read permission to everyone or all:
		sudo chmod a-r test.txt
	-add execute permission to other users:
		sudo chmod o+x test.txt
	-add write permission to user:
		sudo chmod u+w test.txt
	-add execute to other user and add read to group:
		sudo chmod g+r,o+x test.txt
	-set read/write permission for user:
		sudo chmod u=rw test.txt
	-set read/write/execute permission to everyone (rwx rwx rwx --> 421 421 421 --> user group other):
		sudo chmod 777 test.txt
	-set read/write/execute permission to /var/www folder and its subfolder (rwx rwx rwx --> 421 421 421 --> user group other):
		sudo chmod 777 -R /var/www
	-set read/write/execute to user, read to group, read to other (rwx rwx rwx --> 421 421 421 --> user group other):
		sudo chmod 644 test.txt
	-set read/write to user and no permission to group and other (rwx rwx rwx --> 421 421 421 --> user group other):
		sudo chmod 600 test.txt
	-set read/write/execute to user, read/execute to group, read/execute to other (rwx rwx rwx --> 421 421 421 --> user group other):
		sudo chmod 755 test.txt


change file/folder ownership:
	-change index.html file owner:group to www-data:
		sudo chown www-data:www-data index.html
	-change /var/www folder and subfolder owner:group to www-data:
		sudo chown www-data:www-data -R /var/www


find or search file/folder:
	sudo find / -name sources.list

		/              --> start location
		-name          --> name switch
		sources.list   --> name of the file/folder to search

add user:
	sudo useradd username_here

set user unix password:
	sudo passwd username_here

delete user including the home folder(-r switch):
	sudo userdel -r username_here

create group:
	sudo groupadd group_name_here

add a user to a group:
	sudo usermod -a -G group_1_name_here, group_2_name_here  username_here

to check users group:
	sudo groups username_here

users/groups system file:
	/etc/group
	/etc/passwd

to check running program or process:
	-to check if ssh is running:
		sudo ps aux | grep ssh

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to add ppa repository:

	Make sure you already have install python-software-properties:
		sudo apt-get install python-software-properties

	Add PPA repository to my Ubuntu:
		sudo add-apt-repository ppa:<repository-name>/<subdirectory>

to remove ppa repository:

	install ppa-purge:
		sudo apt-get install ppa-purge

	remove PPA repository:
		sudo ppa-purge ppa:<repository-name>/<subdirectory>

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Create TAR:
	sudo tar -pcvzf archive_name.tar dirName/

	-p --> permission
	-c --> create
	-v --> verbose
	-z --> compress or uncompress
	-f --> following is the archive filename
	-x --> extract

Extract TAR:
	sudo tar -pxvzf archive_name.tar

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Create GZIP:
	(used to compress .tar file and is better then tar compress option. the filename becomes archive_name.tar.gz)

	sudo gzip archive_name.tar

Extract GZIP:
	sudo gunzip archive_name.tar.gz

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