checks if progs are available

bash_check_required_progs

function _check_required_programs() {

    # Required program(s)
    req_progs=(readlink xmllint xsltproc curl date sed)
    for p in ${req_progs[@]}; do
	hash "${p}" 2>&- || \
	    { echo >&2 " Required program \"${p}\" not installed or in search PATH."; 
              exit 1; 
            }
    done
    
}