This document discusses Linux users and permissions, file permissions notation and changing permissions with chmod, using pipes to connect commands, installing packages using apt repositories, and basics of the vi text editor. It covers the types of Linux users, numerical and alphabetical notation for file permissions, using chmod to set permissions for users, groups and others, and basic vi commands like insert, write, quit and copy/paste lines.

1. ls
normal user ( regular user )
root user
$
#
ubuntu --------------> root
su
sudo su root
_ _ _ _ _ _ _ _ _ _
3 types of permissions
read -- r
write --- w
execute -- x
_ _ _ _ _ _ _ _ _
owner group others
Numerical notation
Alphabetical notation
Numerical notation
-----------------------------
read -- 4
write -- 2
execute -- 1
f2 ---------- rw- rw- r--
f2 --------- rwx rw- r--
r + w +x -- 4 + 2 +1 = 7

2. 7 -- all permissions
chmod 764 f2
chmod 777 f2
read -- 4
write -- 2
execute -- 1
0 - no permissions
1 -- execute
2 -- w
3 -- wx
4 -- r
5 - rx
6 - rw
7 - rwx
chmod 770 f2
chmod 666 f2
chmod 600 f2
chmod 456 f2
chmod 777 d1
++++++++++++++++++++++
Alphabetical notation
owner -- u
group -- g
others -- o
+
-
f2 ---------- r-- r-x rw-
f2 ---------- r-- r-x rwx

3. chmod o+x f2
f2 ---------- r-- r-x rwx
f2 -------- rw- rwx rwx
chmod u+w,g+w f2
chmod u-w,g-w f2
+++++++++++++++++++++++
f50 ------ rw- rw- r--
f50 ------ rw- --x r--
chmod g=x f50
+
-
=
d1
-------- d2
--------------d3
--------------------d4
++++++++++
The Pipe is a command in Linux that lets you use two or more commands,
such that output of one command serves as input to the next.
head -5 f2 | tail -1
date | wc -l
---------------------
An APT repository is a collection of packages
APT repository allows you to perform package install, removal, upgrade operations on individual packages.
tree d1
To install packages
apt-get install packagename

4. Step 1: Update apt repository
Step 2: Install the package
Syntax of Step 1: Update apt repository
sudo apt-get update
Syntax of Step 2: Install the required package
sudo apt-get install package_name
sudo apt-get install tree
To remove the package
sudo apt-get remove tree
-----------------------------------------
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Vi Editor
-------------
Basic editor in linux
To create a file
i - to go to insert mode
:wq -- save and exit
:q! -- exit without saving
Default mode - command mode
Esc - to come out of insert mode to command mode
dd - to delete a line
yy -- to copy the line
p - to paste below
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