Change swap size in Ubuntu 18.04

Swap is a special area on your computer, which the operating system can use as additional RAM.
Starting with Ubuntu 17.04, the swap partition was replaced by a swap file. The main advantage of the swap file is easy resizing.

In the following example, we’ll extend the swap space available in the /swapfile from 4 GB to 8 GB.

1. Turn off all swap processes
```
sudo swapoff -a
```
2. Resize the swap
```
sudo dd if=/dev/zero of=/swapfile bs=1G count=8
```
  if = input file
  of = output file
  bs = block size
  count = multiplier of blocks
3. Make the file usable as swap
```
sudo mkswap /swapfile
```
4. Activate the swap file
```
sudo swapon /swapfile
```
5. Check the amount of swap available
```
grep SwapTotal /proc/meminfo
```