#!/usr/bin/env bash
LS_ERROR="GVM couldn't find ls"
GREP_ERROR="GVM couldn't find grep"
SORT_ERROR="GVM couldn't find sort"
HEAD_ERROR="GVM couldn't find head"

LS_PATH=`unalias ls &> /dev/null; which ls` || display_error "$LS_ERROR" || return 1
GREP_PATH=`unalias grep &> /dev/null; which grep` || display_error "$GREP_ERROR" || return 1
SORT_PATH=`unalias sort &> /dev/null; which sort` || display_error "$SORT_ERROR" || return 1
HEAD_PATH=`unalias head &> /dev/null; which head` || display_error "$HEAD_ERROR" || return 1