nix-tool

Add packages to your configuration.nix
Except there are two issues: - The code is so "optimized" its barely even readble anymore - The packages are only accepted via stdin

Installation

git clone https://github.com/axtloss/nix-tool.git
cd nix-tool
rustc -C debuginfo=0 -C embed-bitcode=no -C force-frame-pointers=y -C opt-level=z -C target-cpu=native main.rs -o nix-tool
# or
rustc main.rs -o nix-tool

Usage

echo "<pkgs>" | nix-tool path/to/configuration.nix

The modified configuration will be saved as newConfiguration.nix in the directory where you ran the tool

How it works

The code is so small i can dissect it line-by-line and explain it here:

use std::io::{Read, Write};

This Part just imports std::io::Read and std::io::Write
Those were actually the only libraries I couldnt figure out how to use without importing them!

fn main() -> Result<(), Box<(dyn std::error::Error + 'static)>> {

this just is the header of main which return some Results of commands

let args: std::vec::Vec<String> = std::env::args().collect();

Here we just read the args the user passed, only the first one is needed but I couldnt figure out how to only import the first arg

let mut buffer = String::new();

We create a new String in which the stdin input will be saved

std::io::stdin().read_to_string(&mut buffer)?;

The stdin input gets read into buffer which is also just used once, but I cant figure out how to use it without creating a variable

write!(std::fs::File::create("newConfiguration.nix")?, "{}", format!("{}environment.systemPackages = with pkgs;\n  [\n{}\n{}",std::fs::read_to_string(&args[1]).expect("cant open new configuration").split("environment.systemPackages = with pkgs;\n  [").collect::<Vec<&str>>()[0],&buffer.replace(" ", "\n"),std::fs::read_to_string(&args[1]).expect("cant open new configuration").split("environment.systemPackages = with pkgs;\n  [").collect::<Vec<&str>>()[1])).expect("cant write into new configuration");

This is the fun part! so, we use write!() to write the new, modified configuration into newConfiguraiton.nix this file is created in here immediatly with std::fs::File::creat("newconfiguration.nix)
The whole contents are also created on the fly inside of write!() with format!()
First we read the user specified file into a string, immediatly split it at environment.systemPackages = with pkgs;\n [ and write the first part of this new, splitted string
then we add environment.systemPackages = with pkgs;\n [ again, since the .split() seems to remove that part
after that we add the buffer variable, which contains all the packages, but replace spaces with "\n" so that each package is in its own line
then we split the user specified configuartion again, but this time we add the second part of the splitted file

Ok(()) }

To be honest, I dont really know what Ok(()) does, all I know is that its needed when the function is expected to return status stuff