These two bash sequences are not equivalent. My intuition and the bash man page tell me they should be the same.
% export X=x; time --version; unset X -bash: --version: command not found % unset X; X=x time --version GNU time 1.7 Behavior observed in: GNU bash, version 3.2.33(18)-release (i686-pc-cygwin) GNU bash, version 3.1.17(1)-release (i686-redhat-linux-gnu)
