How to add swap space on Ubuntu:

Adding the swap space in Ubuntu follows two steps, in the first step we create the swap file and then in the second step we activate the swap space on Ubuntu, so let’s understand each of these steps one by one:

Create the swap space:

In the first step, we will have to create the swap space, for this, we will have to follow the steps given below:

Step 1: Create the file for swap:

This is the first step, we will create a swap file in the system, for this, we will have to enter the following command:

sudo fallocate -l 2G /swapfile

Lets understand what this command actually says:

fallocate: This is a command-line utility for allocating space to files in various ways, for this case it’s being used to create a file.
-l 2G: This command is used in Ubuntu so that we can create a swap file of size 2 gigabytes, you can change the 2G to other value if you want to increase or decrease the size of swap file.
/swapfile: This is the path and name of the file to be created. In Linux systems, swap files are used as virtual memory.

Output:

sudo fallocate -l 2G /swapfile

If you are getting an error as “allocate failed: Operation not supported” then it means that your system does not have to allocate facility, in that case, you can also use the below command:

sudo dd if=/dev/zero of=/swapfile bs=1024 count=2097152

This command is also used in Ubuntu so that we can create a swap file, but it uses a different approach than the fallocate command, it has the following components:

sudo: This command is used to execute another command with superuser access.
dd: This command is a utility used for converting and copying files. It’s used for tasks like creating disk images.
if=/dev/zero: This option specifies the input file to use. in this case we are using /dev/zero, this is a special file that provides as many null bytes (zeroes) as you read from it.
of=/swapfile: This option specifies the output file to write to. in our case, it’s /swapfile, this is the path and name of the file to be created.
bs=1024: This option is used to set the block size to use. in this case, it’s set to 1024 bytes (1 kilobyte).
count=2097152: This option specifies the number of blocks to copy, since the block size is 1024 bytes and the count is set to 2097152, it creates a file of size 1024 * 2097152 bytes which is equal to 2GB.

Step 2: Set permissions for the file:

Now we will change the permission for this file to 600, this means that regular users can not read/write the file, for this we will use the following command:

sudo chmod 600 /swapfile

This command is used in Ubuntu to modify the permissions of a file named /swapfile, let’s understand the command:

sudo: This command is used to execute another command with superuser access.
chmod: This command is used to change the permissions of a file/directory.
600: This is the permission mode which we are setting for the file. in linux, permissions are represented by three digits, each digit representing permissions for different groups of users: owner, group, and others. In our case, 600 means: the first digit (6) specifies permissions for the owner of the file, which is read and write (4 for read, 2 for write, and 1 for execute, so 4+2=6).
The next two digits are set to 0, which means no permissions for the group and others.
/swapfile: This is the path and name of the file whose permissions we are modifying.

Output:

sudo chmod 600 /swapfile

Step 3: Create Linux Swap area:

Now we will have to create an area for the Linux swap, you will have to use the below command:

sudo mkswap /swapfile

This command is used in Ubuntu so that we can set up the swap area on a specified file. lets understand the command:

sudo: This command is used to execute another command with superuser access.
mkswap: This is the command that we have used to set up a Linux swap area on a device or file.
/swapfile: This is the path and name of the file where the swap area will be set up.

Output:

sudo mkswap /swapfile