Add Ubuntu swap area

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If you want to increase swap space to improve system stability or to cope with low memory conditions, you can create a swap file or allocate a swap partition. Creating a swap file is an easy and fast way, here are the basic steps to create a swap file:

Create an empty file :
Run the following command as root, where /swapfileis the path to the swap file and 1Gis the size of the swap file (for example, 1GB). You can choose different sizes and paths according to your needs.
```
sudo fallocate -l 1G /swapfile
```
Set the correct permissions :
To ensure that only the root user can read and write the swap file, set the correct permissions.
```
sudo chmod 600 /swapfile
```
Set the file as swap space :
```
sudo mkswap /swapfile
```
Enable swap file :
```
sudo swapon /swapfile
```
Make the swap file persistent :
To keep the swap file active across system reboots, add it to /etc/fstabthe file.
```
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
```

After completing the above steps, your system should have new swap space and you can run free -hthe command again to check the status of the swap space.

Code explanation

/swapfile none swap sw 0 0
This line /swapfile none swap sw 0 0is /etc/fstaban entry in the file whose purpose is to specify how to mount and manage the system's swap space. Below is an explanation of each field:

/swapfile: This is the path to the swap file. /swapfileIs a special file created in the file system to expand the system's virtual memory.
none: This field is normally used to specify a mount point, but in this case its value is nonebecause swap space is not a mountable file system.
swap: This field specifies the type of file system. In this case, its value is swap, indicating that this file is a swap file.
sw: This field is an optional mount option. swMeans swap space and allows administrators to activate and deactivate swap space using the swaponand swapoffcommands.
0: This field is used to specify how the system backs up the file system. 0Indicates no backup.
0: This field is used to specify the order in which the file system is checked during system startup. 0Indicates no inspection.

Add this entry to /etc/fstabthe file and the system will automatically enable the specified swap file /swapfileas swap space at startup. This is a way to ensure that the system maintains the swap space configuration across reboots.

echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
This command is used to add the newly created swap file ( /swapfile) to the system's file system table ( /etc/fstab) so that the system can be started every time The swap file can be automatically mounted and used as swap space. Below is an explanation of each part of the command:

echo: echoCommand is used to output the specified string in the terminal. Here, the string it outputs is '/swapfile none swap sw 0 0'.
'(Single quotes): Used to surround the string to be output, ensuring that the string is passed intact to the next command.
|(pipe symbol): This symbol is used to pass the output of the previous command ( echo) to the next command ( sudo tee). In this way, echothe output of the command becomes sudo teethe input of the command.
sudo: Execute the following commands with superuser (root) permissions tee.
teeThe : teecommand is used to read standard input and write it to a file and standard output. Here, it will echowrite the string received from the command to a file /etc/fstab.
-a: This option tells teethe command to append the contents to the end of the file rather than overwriting the existing contents of the file.
/etc/fstab: This is the path to the file to be written. /etc/fstabIt is the system's file system table, which contains information about how the system should mount and use various file systems and devices.

Specifically, '/swapfile none swap sw 0 0'this string is fstaba new record in the file, which tells the system /swapfilethat is a swap space file and should be automatically mounted and used as swap space when the system starts.