Rename files in linux / bash using mv command without typing the full name two times

mv.sh

# Put this function to your .bashrc file.
# Usage: mv oldfilename
# If you call mv without the second parameter it will prompt you to edit the filename on command line.
# Original mv is called when it's called with more than one argument.
# It's useful when you want to change just a few letters in a long name.
#
# Also see:
# - imv from renameutils
# - Ctrl-W Ctrl-Y Ctrl-Y (cut last word, paste, paste)

function mv() {
  if [ "$#" -ne 1 ] || [ ! -e "$1" ]; then
    command mv "$@"
    return
  fi

  read -ei "$1" newfilename
  command mv -v -- "$1" "$newfilename"
}

There are even more flexible ways (in bash, at least), for example (here renaming .txt to .json):

$ touch config.txt
$ mv config.txt !#:1:s/txt/json

This one eludes me, care to explain how it works?

I would recommend adding --interactive to the mv commands in the script. As it is now, it is possible to overwrite existing files with no confirmation using this script.

With the fish shell, you can type Alt-E to edit any command line in your favorite editor where you likely already know shortcuts for copying, pasting and modifying. The great thing is that is a general solution that works for any command line edits.

In bash it is C-x C-e