Improved README.md

README.md

@@ -8,7 +8,27 @@ Have you ever wanted to be able to do `find -type f -name "*.ml"`, or any other
 search command, only inside a tar file?
 
 If you've experienced any of the above, this is your lucky day! Just mount the
-tar file to a directory:
+tar file to a directory with fusetar! This program allows you to mount a tar file
+as if it were a disk or some other filesystem-containing device. The files inside
+the archive are presented transparently as if they were files in a regular filesystem.
+
+Some advantages of doing this instead of just extracting the tarball:
+
+This does not require extraction - you can just mount, take a peek, search through files and copy files out, then unmount. This program only performs read operations, the archive is not modified.
+
+This also means that your filesystem is not polluted. For example, if you wanted to search for a particular file's contents, you would normally have to extract the archive and search with `find`. If the archive is large, this is potentially expensive. With this program you don't have to do any of that - just mount it!
+
+It doesn't keep the entire file in memory, so you can still access arbitrarily large tar files. File contents will only be fetched from disk when requested.
+
+Finally, your access to the archive is fully transparent. You do not need to learn any flags or anything - any commands that search through, index or otherwise access files will now work on tar.
+
+Some disadvantages:
+
+It's always read-only, so the contents of your archive are preserved. Tar is a streaming format, and it is quite awkward to try to make changes/additions to it, which is why the program currently does not support write operations.
+
+I/O performance may be affected. As mentioned, tar is a streaming format, and therefore file access can be inefficient.
+
+# Examples
 
 ```sh
 $ fusetar my-archive.tar mnt/
@@ -17,6 +37,8 @@ $ fusetar my-archive.tar mnt/
 And just like that, everything inside the tarball is available to you as a
 read-only file system, to search, read or do whatever else.
 
+## Debian rootfs
+
 An example with the debian rootfs:
 
 ```sh
@@ -25,14 +47,12 @@ $ wget https://github.com/kbaraniak/debian-rootfs/releases/download/bookworm-270
 $ xz -d debian-amd64-bookworm-rootfs-270224.tar.xz
 $ mkdir -p mnt
 $ fusetar debian-amd64-bookworm-rootfs-270224.tar mnt/
-$ ls debian-amd64-bookworm-rootfs-270224.tar.xz
+$ ls mnt/
 bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
 ```
 
 As you can see, the root file system inside the tar archive is transparently presented to you now under your mounted directory!
 
-Note that it is read-only. Tar is a streaming format, and it is quite awkward to try to make changes/additions to it.
-
 With that being said, if you absolutely need to write files to the directory (but not to the archive), it is quite easy to make this directory writable - you can simply use overlayfs to overlay an empty directory over this mount. This way, your changes would be preserved inside a separate directory, while unchanged content from the archive remains available:
 
 ```sh
@@ -66,3 +86,25 @@ drwxr-xr-x 1 root     root    0 Jul  2  2023 tmp
 drwxr-xr-x 1 root     root    0 Jul  2  2023 usr
 drwxr-xr-x 1 root     root    0 Feb 27  2024 var
 ```
+
+
+# Build
+
+In order to build this program, you need to have the following installed:
+
+- ocaml 5.3
+- dune 3
+- ocamlfuse
+- findlib
+
+You can install all of these through opam, or through your distribution's package manager if your distribution packages them.
+
+Once you have these, you can build with `dune build`, and install with `dune install`. You can tell it where to install, e.g. `dune install --prefix /usr/local/`.
+
+## Nix
+
+If you are on NixOS, or are willing to install the nix package manager, you can also use the provided `default.nix` (just run `nix-build`). This will download all dependancies and build. It should produce a symlink called `result`, which will point to the results (containing the produced binary under bin/). You can then place the binary wherever you like.
+
+For development purposes, you can also use the provided `shell.nix`, with `nix-shell`. This will drop you in a development shell, with all necessary packages to build & develop.
+
+If you have nix and direnv (with nix-direnv) installed, you can simply allow the provided .env file. This will automatically put you in a shell environment with all necessary packages.