assignment: saving current progress for this evening

src/skynet/nix.md

@@ -1,7 +1,30 @@
 # Nix/NixOS
+The [Skynet Cluster][nixos_skynet] is (for the most part) running on a Linux variant called NixOS.  
+This article aims to introduce you to Nix and Nixos in order to get you up to speed to administer the cluster.
 
 ## What it is
 ### Nix
+#### Package Manager
+The word Nix refers to two things: a language and a package manager.  
+These are deeply interlinked together with the language being how the package manager is able to do its job.   
+Nix grew out of a [PhD by Eelco Dolstra][nix_paper] wherein he proposes a slightly different way to manage dependencies on a system.
+
+For most Linux systems programs make use of other software installed on the computer, for the most part this works fine.  
+Where issue may arise is if one program needs to update one of these dependencies, specially a minor or major patch where backwards compatibility is not guaranteed.  
+If another program is using this (system wide) dependency then it may run into interface issues when using it.  
+In a sense updating one program can break another on the system.
+
+The route the Nix package manager takes is it treats each program as a function.  
+Using teh Nix language a function for that package is created which states what inputs are required, what is needed to turn those inputs into teh program as well as the name for the output.  
+The output is then saved in a read only location in the format of ``/nix/store/$hash-program-name-version``.  
+This output can eitehr be used as the input of another program or be used as is by the system/user.  
+Using this format means that any change in the inputs or the program itself will result in a different output.  
+This means that multiple versions of the program (some even the same version but different commit) can co-exist on the one system.  
+An example using different versions of Firefox:  
+![img.png](nix/firefox_co-existing.png)
+
+#### Language
+
 
 ### Flakes
 
@@ -28,3 +51,7 @@
 #### Deployment
 
 
+
+
+[nixos_skynet]: https://forgejo.skynet.ie/Skynet/nixos
+[nix_paper]: https://edolstra.github.io/pubs/nspfssd-lisa2004-final.pdf