ubuntu bash CentOS

~	/home/ya
pwd	show path
uname -a	print system info
`uname -a`	in bash excute it and replace with command output
chmod	change permission: chmod X@Y file1 file2 ... where: X is any combination of the letters `u' (for owner), `g' (for group), `o' (for others), `a' (for all; that is, for `ugo'); @ is either `+' to add permissions, `-' to remove permissions, or `=' to assign permissions absolutely; and Y is any combination of `r', `w', `x' read write execute
touch	create file
	internet
ifconfig	internet config
	programming
ls -al	show dir content
ls -al	show dir content
ls -al	show dir content
ls -al	show dir content
	user management
passwd userName	set password to user
su userName	change user
exit	log out
userdel userName -r	delete user. -r with user dir.
	system
sudo shutdown -r 0	reboot через 0 секунд
ctrl+alt+F1-9	run console in full screen mode
clear	clear terminal

Symbolic Notation	Numeric Notation	English
----------	0000	no permissions
---x--x--x	0111	execute
--w--w--w-	0222	write
--wx-wx-wx	0333	write & execute
-r--r--r--	0444	read
-r-xr-xr-x	0555	read & execute
-rw-rw-rw-	0666	read & write
-rwxrwxrwx	0777	read, write, & execute