Swap File for Ubuntu 20.04, 22.04 and 24.04

Alternatively to setting up a swapfile, compress the memory of the Ubuntu Linux machine.

Ubuntu can be downloaded from here.

Check If Swap File Is Already Installed

Some installations may already have a swap file setup. Issue this command in the Terminal:

sudo free -h

The output should look something like this if one is not configured:

              total        used        free      shared  buff/cache   available
Mem:          475Mi       155Mi       6.0Mi       0.0Ki       313Mi       298Mi
Swap:            0B          0B          0B

Create a Swap File

Create a 4 GiB swap file in the root directory with fallocate:

sudo fallocate -l 4G /swapfile

Should fallocate not be available, use dd.

sudo dd if=/dev/zero of=/swapfile bs=1k count=2048k

Allow Only ROOT User Access to the Swap File

Only the root user should be accessing the newly created swap file. Issue command:

sudo chmod 600 /swapfile

Make the New File the Swap File

Use mkswap as follows:

sudo mkswap /swapfile

Activate the Swap File

Use swapon as follows:

sudo swapon /swapfile

Edit the /etc/fstab File

Use nano as follows to modify this file, adding one line:

sudo nano /etc/fstab

This file should have a line reading this:

/swapfile swap swap defaults 0 0

Verify the Installation

Use free to check the swapfile

sudo free -h

The output should look something like this:

              total        used        free      shared  buff/cache   available
Mem:          475Mi       155Mi       6.0Mi       0.0Ki       313Mi       298Mi
Swap:         4.0Gi        10Mi       4.0Gi

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