Best way to add and install runtime dependency to an existing package in Nix?

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Installing package in Nix with nix-env -i <pkg> and adding Nix environment with source ~/.nix-profile/etc/profile.d/nix.sh causes that package to appear on top of the $PATH which is usually desirable.

What if I want to install and specify a runtime dependency (e.g. python or perl interpreter) for already existing package but don't want the dependency to appear for the rest of packages and system environment?

In my case I want to add perl dependency to fzf package as it uses perl here. But I don't want it to be present for the rest of the system for compatibility reasons.

I tried overriding fzf with packageOverrides but first it seems to work only for build dependencies and second there is no argument to specify perl.

nix
1 Answers

Usually you'd use wrapProgram to replace an executable by a script that modifies PATH before invoking the real executable.

In this case it's a bit more complicated, because it's not a standalone program but a script to be imported, so it can not use a wrapper. In postInstall you could use substituteInPlace, which will look somewhat like

substituteInPlace $out/path-to-keybindings.zsh --replace '| perl ' '| ${pkgs.perl}/bin/perl '

This will patch the script to reference perl by its absolute store path, without modifying the environment.

user_4285860
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