How to create swap in Linux

CREATE SWAP PARTITION LINUX

We can create a 8 Gigabyte Swap Partition
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sudo fallocate -l 8G /swapfile
ls -lh /swapfile

Enabling the Swap File
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sudo chmod 600 /swapfile
ls -lh /swapfile

Now that our file is more secure, we can tell our system to set up the swap space by typing:
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sudo mkswap /swapfile

Our file is now ready to be used as a swap space. We can enable this by typing:
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sudo swapon /swapfile

We can verify that the procedure was successful by checking whether our system reports swap space now:
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sudo swapon -s

We have a new swap file here. We can use the free utility again to corroborate our findings:
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free -m

Make the Swap File Permanent
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Edit the file with root privileges in your text editor:

sudo vim /etc/fstab

At the bottom of the file, you need to add a line that will tell the operating system to automatically use the file you created:

For ubuntu

swapfile none swap sw 0 0

For Centos

swapfile swap swap defaults 0 0

Save and close the file when you are finished.

cat /proc/sys/vm/swappiness

it should be 30

sudo sysctl vm.swappiness=10

vm.swappiness = 10

How to remove swap memory ?

swapoff -v /swapfile
rm -rf swapfile

Script to create swap memory

#!/bin/bash
echo " Enter the amount of ram to be created with G example - you need to create ram of 2GB then just type 2G and press enter"
read ram
sudo fallocate -l $ram /swapfile
ls -lh /swapfile



sudo chmod 600 /swapfile
ls -lh /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
sudo swapon -s
free -m
sudo echo "swapfile none swap sw 0 0" | tee >> /etc/fstab
cat /etc/fstab
cat /proc/sys/vm/swappiness
sudo sysctl vm.swappiness=10