I have been using biterscripting a lot to do stuff like this from command mode.
Some sample code:
# Get the time stamp.
var str timestamp
# Get the file extension - after the last dot (assuming file name is in $file)
var str extension
stex "[^.^l"$ $file >$extn # ^.^ means find a dot, l means the last instance, [ means strip
# off everything beginning with the last dot.
# Add timestamp to the file name
set $file = $file + $timestamp
# Add back the extension
set $file = $file + $extension
# $timestamp has the format yyyymmddhhmmss . You can format it further. For example, if you just want the
# date (and no time), use the following
chex "8[" $timestamp > null # 8 means 8th character, [ means extract everything after the 8th char,
# >null means don't show the extracted content on screen.