Overview

This package contains a collection of Nix expressions created by SHARCNET staff for various software packages. You can use them to install the associated packages into your Nix environment.

These directions assume you have loaded the Nix module (this enables your Nix environment and makes the various Nix commands available)

module load nix

Obtaining the latest expressions

If you don't yet have a copy of ~/nix-nixpkgs-sharcnet, you will need to clone a copy (use your SHARCNET credentials)

cd ~
git clone https://git.sharcnet.ca/nix/nixpkgs-sharcnet.git

If you already have a copy, you can update to the latest version

cd ~/nix-nixpkgs-sharcnet
git pull

Using an expression

Once you have a copy of the expressions you can use nix-env to install, update, or remove them from your environment.

Installing an expression

To install (or update) a package pass the corresponding file (replace package.nix in what follows) to nix-env using the --file option

nix-env --install --file package.nix

You can also copy or symlink the file into your ~/.nix-defexpr directory and then refer to it as a top-level attribute (replace package with the base name of the copied file)

nix-env --install --attr package

Removing

To remove a package you first need to figure out its name (generally, but not necessarily, the same as the name of the Nix expression file)

nix-env --query

Then you (replace package with the package name)

nix-env --uninstall package

Reverting

To undo the last install/update/remove command

nix-env --rollback

Creating an expression

The best way to create a new package is to pillage existing package expressions. This includes the ones in this repository (click the repository tab to see the files) and all the various upstream ones (click on a package and then following the Nix expression link). The packaging manual details all the various options you will see in these files.

Building

A package can be build by running (replace file.nix with the name of your file)

nix-build file.nix

If the build succeeds, the output will be symlinked into the current directory as result.

Debugging a build

A simulated build environment can be entered by running (replace file.nix with the name of your file)

nix-shell --pure file.nix

which gives you a shell in the build environment described by the epxression. The default build and install locations need to be overriden to somewhere you have write permission (this uses /tmp)

NIX_BUILD_TOP=/tmp/nix-$USER

mkdir "$NIX_BUILD_TOP"
cd "$NIX_BUILD_TOP"
mkdir out
out=$PWD/out
prefix=$out

Then you can invoke the standard nix build phases and use the fact that you are in a shell to diagnose whatever goes wrong (setting NIX_ENFORCE_PURITY enables various checks along the way to ensure no host bits get into the results as these would not be available in the real sandboxed build)

export NIX_ENFORCE_PURITY=1

unpackPhase
cd "$sourceRoot"

configurePhase
buildPhase
installPhase