zfsbootmenu-preinit: single-quote values written to /etc/zfsbootmenu.conf

These values are interpolated during preinit when they are written, so
the file will only contain string literals that should not be further
interpreted. This also works around an issue where appending '\' to
parameters (e.g., 'zbm.prefer=pool\' on the command line) would cause a
parsing error while sourcing the configuration.

Author: ahesford

zfsbootmenu/pre-init/zfsbootmenu-preinit.sh

@@ -21,19 +21,19 @@ export BASE="/zfsbootmenu"
 # shellcheck disable=SC2154
 cat >> "/etc/zfsbootmenu.conf" <<EOF
 # BEGIN additions by zfsbootmenu-preinit.sh
-export BASE="${BASE}"
-export spl_hostid="${spl_hostid}"
-export import_policy="${import_policy}"
-export menu_timeout="${menu_timeout}"
-export loglevel="${loglevel}"
-export zbm_prefer_pool="${zbm_prefer_pool}"
-export zbm_require_pool="${zbm_require_pool}"
+export BASE='${BASE}'
+export spl_hostid='${spl_hostid}'
+export import_policy='${import_policy}'
+export menu_timeout='${menu_timeout}'
+export loglevel='${loglevel}'
+export zbm_prefer_pool='${zbm_prefer_pool}'
+export zbm_require_pool='${zbm_require_pool}'
 export default_hostid=00bab10c
-export zbm_sort="${zbm_sort}"
-export zbm_set_hostid="${zbm_set_hostid}"
-export zbm_import_delay="${zbm_import_delay}"
-export zbm_hook_root="${zbm_hook_root}"
-export control_term="${control_term}"
+export zbm_sort='${zbm_sort}'
+export zbm_set_hostid='${zbm_set_hostid}'
+export zbm_import_delay='${zbm_import_delay}'
+export zbm_hook_root='${zbm_hook_root}'
+export control_term='${control_term}'
 # END additions by zfsbootmenu-preinit.sh
 EOF