Now that we have a file of the correct size available, we need to actually turn this into swap space.
First, we need to lock down the permissions of the file so that only the users with root privileges can read the contents. This prevents normal users from being able to access the file, which would have significant security implications.
Make the file only accessible to root by typing:
sudo chmod 600 /swapfile
Verify the permissions change by typing:
ls -lh /swapfile
-rw------- 1 root root 1.0G Apr 25 11:14 /swapfile
As you can see, only the root user has the read and write flags enabled.
We can now mark the file as swap space by typing:
sudo mkswap /swapfile
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes) no label, UUID=6e965805-2ab9-450f-aed6-577e74089dbf
After marking the file, we can enable the swap file, allowing our system to start utilizing it:
sudo swapon /swapfile
Verify that the swap is available by typing:
sudo swapon --show
NAME TYPE SIZE USED PRIO /swapfile file 1024M 0B -2
We can check the output of the
free utility again to corroborate our findings:
total used free shared buff/cache available Mem: 985M 84M 220M 680K 680M 722M Swap: 1.0G 0B 1.0G
Our swap has been set up successfully and our operating system will begin to use it as necessary.