haskell-te: d7b5ab44f1a4cf2bc14bdeb7696707b7e1b4ca7b

     1: { bash, fail, gnugrep, mkBin }:
     2: 
     3: mkBin {
     4:   name   = "haveVar";
     5:   paths  = [ bash fail gnugrep ];
     6:   script = ''
     7:     #!${bash}/bin/bash
     8:     set -e
     9: 
    10:     [[ "$#" -eq 1 ]] || fail "haveVar needs 1 arg, given $#"
    11: 
    12:     echo "''${!1}" | grep '\S' > /dev/null || fail "No '$1' variable set"
    13: 
    14:     exit 0
    15:   '';
    16: }