nix-target.sh

#!/usr/bin/env bash

set -euo pipefail

args=()

while [ ! -z ${1+x} ]; do
    case $1 in
	-o|--out-link)
	    shift
	    if [ -z ${1:+x} ]; then
		echo "error: flag '-o' requires 1 argument(s)" 1>&2
		exit 1
	    else
		out=$1
	    fi
	    ;;
	--no-link) ;; # This is the default, and passing this through
		      # would break the smylinks we use to print
		      # outputs
	*)
	    args+=("$1")
	    ;;
    esac
    shift
done

if [ ! -z ${help+x} ]; then
    nix build --help
    exit 0
fi

if [ -z ${out:+x} ]; then
    outbase=out
else
    outbase=$(basename $out)
    outdir=$(dirname $out)
fi

DIR=$(mktemp -d --tmpdir)
trap "rm -rf $DIR" EXIT

nix build -o $DIR/$outbase -f ./default.nix "${args[@]}"

if test $(find $DIR -maxdepth 0 -empty); then
    exit 0
fi

readlink $(find $DIR -mindepth 1)

if [ ! -z ${outdir+x} ]; then
    for f in $(ls $DIR); do
	if ([ -L $outdir/$f ] && [[ $(readlink $outdir/$f) != /nix/store/* ]]) || ([ -e $outdir/$f ] && [ ! -L $outdir/$f ]); then
	    echo "error: cannot create symlink '$outdir/$f'; already exists" 1>&2
	    exit 1
	fi
    done
    for f in $(ls $DIR); do
	nix-store --add-root $outdir/$f --indirect -r $(readlink $DIR/$f) > /dev/null
    done
fi

rm $DIR/*
nix-store --delete 2> /dev/null > /dev/null