Last Sync: 2022-07-30 14:00:04

Operating_Systems/Basic_Model.md

@@ -4,7 +4,7 @@ tags:
   - Linux
 ---
 
-# Basic model of a (*nix) operating system
+# Basic model of a *nix operating system
 
 We can abstract the Linux OS into three operational levels or tiers, from the bottom up:
 

Operating_Systems/Disks/Filesystems.md

@@ -51,3 +51,5 @@ touch test.txt
 Our `sda1` partition is now mounted at `mountpoint`. We can go ahead and create files. If we now look within the graphical file manager when we click on the `sda1` volume, we will see the new file we have created in `mountpoint`.
 
 ![](/img/mount-directory.png)
+
+## `fstab` 

Operating_Systems/Disks/Swap_space.md

@@ -0,0 +1,34 @@
+---
+tags:
+  - Linux
+  - Operating_Systems
+  - disks
+  - devices
+  - disk-partions
+---
+
+# Swap space
+
+A swap partition is a partition on a disk that is not intended to be used as a filesystem. Instead, it is a part of the disk that is used to augment the main memory. 
+
+If you run out of memory and have set up a swap partition, the OS will be able to move pieces of memory to and from disk storage. This is called _swapping_ because pieces of idle programs are swapped to the disk in exchange for active pieces residing on the disk.
+
+## View current swap usage
+If you have a swap space established, the command `free` will show current usage: 
+
+```bash
+free
+               total        used        free      shared  buff/cache   available
+Mem:        16099420     3031572    10157652     1153144     2910196    11605820
+Swap:        3145724           0     3145724
+```
+
+## Create a swap partition
+To use an existing disk partition as a swap you can run the command `mkswap [device]` and then `swapon [device]` to register the space with the [kernel](/Operating_Systems/The_Kernel.md).
+
+### Add to `fstab`
+You will want the swap to be activated every time the OS boots so add the following line to the [fstab](/Operating_Systems/Disks/Filesystems.md#fstab), where `/sda3` is used as the example partition:
+
+```bash
+/dev/sda3e none swap sw 0 0
+```