# Set a PATH (!!! impure). export PATH=/bin:/usr/bin:$PATH mkdir $out cat > $out/substituter <<EOF #! /bin/sh -ex echo \$* case \$* in *aaaa*) echo "Closure([\"\$2\"],[(\"\$2\",[])])" > \$1 ;; *) mkdir \$1 echo \$3 \$4 > \$1/hello ;; esac EOF chmod +x $out/substituter