/usr/local/bin/timestamp

#! /bin/sh

for oldname ; do
  ts=`date +'%Y%m%d%H%M' --reference="$oldname"`

  newname=`echo $oldname | sed -nre "s/^(\\.?)([^\\.]+)(-[[:digit:]]{12})(\\..*)\$/\\1\\2-$ts\\4/p"`
  if [ -z "$newname" ]; then
    newname=`echo $oldname | sed -nre "s/^(\\.?)([^\\.]+)(\\..*)\$/\\1\\2-$ts\\3/p"`
  fi
  if [ -z "$newname" ]; then
    newname=`echo $oldname | sed -nre "s/^(\\.?)([^\\.]+)(-[[:digit:]]{12})\$/\\1\\2-$ts/p"`
  fi
  if [ -z "$newname" ]; then
    newname=`echo $oldname | sed -nre "s/^(\\.?)([^\\.]+)\$/\\1\\2-$ts/p"`
  fi

  if [ -f "$newname" ]; then
    if [ "$newname" != "$oldname" ]; then
      echo "Can't rename $oldname to $newname: file already exists."
    fi
  else
    echo mv "$oldname" "$newname"
    mv "$oldname" "$newname"
  fi
done

As I’m using KDE as my desktop, I like to have the timestamping integrated. Fortunately, it’s easy.

~/.kde/share/apps/konqueror/servicemenus

Actions=timestamp
ServiceTypes=all/all

[Desktop Action timestamp]
Exec=/usr/local/bin/timestamp %u
Icon=clock
Name=Timestamp

See Creating Konqueror Service Menus for a general introduction.

Update, 2007-02-06

I’ve updated the script to insert the timestamp before all the first extension and to also work with filename starting with a ‘.‘.