Comment by ricket

btw there is a bash feature that you can use for this

touch a_tset_file.txt mv a_t{se,es}t_file.txt

it works for changing file extensions:

touch foo.txt mv foo.{txt,json}

or for adding or removing characters, just leave the other side of the comma empty

touch foo.txt mv foo{,bar}.txt mv foo{bar,}.txt