Bash script to create symlink

Need a script to automatically create/update a symlink to the most recent directory. I want to make a shell script which will create or update a symlink (named "current") so that it automatically points to the subdirectory with the most recent date. For example, given these subdirectories: 2009.03.21_00.50.02 2009.03.21_11.31.42 2009.03.22_07.55.47 2009.03.22_10.59.20 2009.04.03_23.21.38 2009.04.15_11.06.08 2009.04.16_00.50.02 2009.04.18_20.35.26 I want the script to create or update a symlink like this: current -> 2009.04.18_20.35.26/ the symlink will reside at the same level as the directories 2009.04.18_20.35.26, etc. When the bash script is run next, if there is a new directory named e.g., 2009.04.20_16.15.06, (and this is the most recent) the symlink should be updated to: current -> 2009.04.20_16.15.06/