Shell Scripts
the package writeShellScript can be used to add shell scripts to nix expressions
someBuildHelper = { name, sha256 }:
stdenv.mkDerivation {
inherit name;
outputHashMode = "recursive";
outputHashAlgo = "sha256";
outputHash = sha256;
builder = writeShellScript "builder.sh" ''
echo "hi, my name is ''${0}" # escape bash variable
echo "hi, my hash is ${sha256}" # use nix variable
echo "hello world" >output.txt
'';
};
Packaging
example:
# nix-build -E 'with import <nixpkgs> { }; callPackage ./default.nix { }'
{ stdenv
, lib
, fetchFromGitHub
, bash
, subversion
, makeWrapper
}:
stdenv.mkDerivation {
pname = "github-downloader";
version = "08049f6";
src = fetchFromGitHub {
# https://github.com/Decad/github-downloader
owner = "Decad";
repo = "github-downloader";
rev = "08049f6183e559a9a97b1d144c070a36118cca97";
sha256 = "073jkky5svrb7hmbx3ycgzpb37hdap7nd9i0id5b5yxlcnf7930r";
};
buildInputs = [ bash subversion ];
nativeBuildInputs = [ makeWrapper ];
installPhase = ''
mkdir -p $out/bin
cp github-downloader.sh $out/bin/github-downloader.sh
wrapProgram $out/bin/github-downloader.sh \
--prefix PATH : ${lib.makeBinPath [ bash subversion ]}
'';
};
when the dependency subversion is missing, the script throws the error svn: command not found
wrapProgram will move the original script to .github-downloader.sh-wrapped
Posix Shell
some environments (like OpenWRT, via busybox) offer only a "limited" shell (sh instead of bash).
on nixos, posix shells are provided by the packages dash and posh