Linux Cookbook

cp [Option(s)] [Original(s)] [Destination]
-n # Existing files are never overwritten.
-r # Directories are copied recursively including subdirectories.
-u # Copies the file only if the destination file is older than the original.
-p # Inherite the permission

mkdir [Option(s)] Directory
-p # Creates missing intermediate path name directories. 

Increase volume

sudo cfdisk
# Physical Volumn - PV
sudo pvdisplay
sudo pvresize /dev/sda3
# Volumn Group - VG
sudo vgdisplay
# Logical Volumn - LV
sudo lvdisplay
sudo lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
sudo resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv

Check disk usage

# Partiction usage
duf

# Storage usage
ncdu

Setting Up Proxy for APT

sudo nano /etc/apt/apt.conf

Acquire::http::Proxy "http://[username]:[password]@ [proxy-web-or-IP-address]:[port-number]";
Acquire::https::Proxy "http://[username]:[password]@ [proxy-web-or-IP-address