In general, there’s four ways to install software in Nix:

• Using nix-shell -p <package>, which gives you a shell with an emphemeral install of the package;
• using nix-env -i as yourself;
• using nix-env -i as root;
• and editing environment.systemPackages in configuration.nix.

The first is useful for one-off tasks or experimenting with new packages, since the packages will be subject to garbage collection once you close the shell, but for this reason it’s not good for things you use day to day.

The second installs the package just for you (and doesn’t require root!). This lets ordinary users install packages just for themselves. The third is similar, but packages installed in this manner by root are available to all users. This is probably the closest to “traditional” package management, but like traditional package management the set of installed packages isn’t stored in ~, but in /nix/var/nix/profiles/per-user/ – so backing up someone’s user directory won’t back up their preferred set of installed packages! I find this alarming.

The last gets you a system-wide package install that is recorded in /etc/nixos, making it a convenient central location for version control and backups. For this reason I’ve been using environment.systemPackages exclusively for permanent package installs.

Day to day programs

Most of the stuff I use on a daily basis is listed in the package search and is straightforward to install. I needed gitAndTools.gitFull rather than just git to get stuff like gitk, but the command-not-found tool pointed me in the right direction. For the most part it’s just a matter of adding the packages to systemPackages and then running nixos-rebuild switch to activate them.

hledger and conflicting dependencies

I use hledger and hledger-web for (my attempts at) accounting. This is where some weirdness happened: hledger-web is version 1.0, and requires hledger 1.0, but hledger is 0.27.

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By default, when you install NixOS, it’s configured to install software from the nixos-<release> channel. This is the set of software at the time the release was cut + stability and security updates, but not generally any major version changes. A new release is cut every six months.

There’s also the unstable channel, which tracks the current state of the nixpkgs repository – modulo testing; commits that don’t pass CI won’t get pushed to the channel. This gives you a more rolling-release style experience, and like Tumbleweed, is sometimes exciting.

There’s a whole pile of packages that I use on a daily basis, so all of those get added to systemPackages.