https://github.com/pdfjam/pdfjam/issues/99

Index: texmf-dist/scripts/pdfjam/pdfjam
--- texmf-dist/scripts/pdfjam/pdfjam.orig
+++ texmf-dist/scripts/pdfjam/pdfjam
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!${LOCALBASE}/bin/bash
 version=4.1
 #########################################################################
 ##                                                                     ##
