03_OS

Basic OS

hostnamectl

uname -a

cat /etc/os-release

sudo do-release-upgrade -c

sudo do-release-upgrade

showing or hiding grub menu

press and hold the SHIFT button while booting.

or:

sudo nano /etc/default/grub

change GRUB_TIMEOUT to -1 and comment out GRUB_HIDDEN_TIMEOUT

sudo update-grub

sudo swapon --show

show free memory:

free -h

allocate 1GB to swap file:

sudo fallocate -l 1G /swapfile

check the swap file permission:

ls -lh /swapfile 

sudo chmod 600 /swapfile

make swap active:

sudo mkswap /swapfile 

sudo swapon /swapfile 

sudo swapon --show

make the swap permanent:

sudo nano /etc/fstab

add /swapfile none swap sw 0 0 if it does not exist