echo ($(ldap-query-for-valid-users)) > /tmp/all-users.sexp should be something like x=$(ldap-query-for-valid-users); test ${#x} -gt 0||exec echo no va

echo ($(ldap-query-for-valid-users)) > /tmp/all-users.sexp should be something like x=$(ldap-query-for-valid-users); test ${#x} -gt 0||exec echo no valid users >&2; echo \("$x"\) > /tmp/all-users.sexp; This way they would get the message "no valid users" to stderr and the script would exit. According to the blog post that is what they wanted. Alternatively, x=$(ldap-query-for-valid-users); test ${#x} -gt 0||exit 100 echo \("$x"\) > /tmp/all-users.sexp; if they prefer a nonzero exit code to a message to stderr.