Description of changes

I often like to use nix run to use a package that's currently not installed on my system. Sometimes I run into cases where nix run fails due to the package's name differing from that of the executable. I've filed a few PRs manually adding mainProgram to few packages' meta attribute set to get them working with nix run. This is kind of annoying to do, so I got to thinking about whether there was a way I could automate this. This is my first attempt.

I created a hacky script that uses nix-{index,locate} to try and:

• find all packages that included a single executable in /bin;
• check if the single executable's name was an exact match for the packages name in nixpkgs; and
• if it wasn't an exact match,
  • check whether the package's meta attribute set contained a mainProgram attribute; and
  • if it didn't, adds the mainProgram attribute, set to the name of the single executable.

I excluded packages defined in places like pkgs/development/{libraries,haskell-modules} and a few others to reduce false positives.

I then manually looked through the diff to sanity check the changes, spot checking many with nix run (especially the ones that looked the most suspect) and removed a few where the single executable didn't really make sense to define as the mainProgram.

This process will have missed a bunch of cases, e.g.,

• cases where the package has a single executable, but it was wrapped, so a second executable was present in /bin with the suffix "-wrapped";
• cases where my in-place substitution with sed failed;
• among many others.

But even at that, this PR should enable nix run to work with 143 additional packages.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.