The development version of bash seems to handle brace expansion differently than the stable version.
The relevant code: ------------------------------------------------------------------------------- Code ------------------------------------------------------------------------------- echo "$BASH_VERSION" echo $RANDOM{,,,} ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- master ------------------------------------------------------------------------------- 4.2.39(1)-release 30011 30767 22583 12713 ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- devel ------------------------------------------------------------------------------- 4.3.0(2)-devel 14730 ------------------------------------------------------------------------------- I would expect these to be similar. -- Eduardo A. Bustamante López