use env, a posix command

cloudinit/sources/DataSourceOpenNebula.py

@@ -321,23 +321,11 @@ def parse_shell_config(content, asuser=None):
         )
     )
 
-    def varprinter(vlist):
-        # output '\0'.join(['_start_', key=value NULL for vars in vlist]
-        return "\n".join(
-            (
-                'printf "%s\\0" _start_',
-                "for __v in %s; do" % " ".join(vlist),
-                '   printf "%s=%s\\0" "$__v" "${!__v}";',
-                "done",
-                "",
-            )
-        )
-
     # the rendered 'bcmd' is bash syntax that does
     # setup: declare variables we use (so they show up in 'all')
-    # varprinter(allvars): print all variables known at beginning
+    # env: print all variables known at beginning
     # content: execute the provided content
-    # varprinter(keylist): print all variables known after content
+    # env: print all variables known after content
     #
     # output is then a null terminated array of:
     #   literal '_start_'
@@ -347,10 +335,10 @@ def varprinter(vlist):
     bcmd = (
         "unset IFS\n"
         + setup
-        + varprinter(allvars)
+        + "env\n"
         + "{\n%s\n\n:\n} > /dev/null\n" % content
         + "unset IFS\n"
-        + varprinter(keylist)
+        + "env\n"
         + "\n"
     )