Simple file renaming script

Just a reminder to myself of a simple approach to renaming some media files I was working with. My first attempt ended up creating a long and unwieldy single-line script. This was too difficult for the human mind to parse. A few minutes later I tried again and came up with the following which I much prefer.

#!/bin/bash
COUNTER=1
SUFFIX=""
#loop over the files with certain suffixes ( .MTS, .JPG, .MP4)
for f in $(ls|grep -E "MTS$|JPG$|MP4$") 
  do
    # get the suffix of this file to append later.
    SUFFIX=${f#*.} 
    printf "mv "
    printf $f
    printf " "
    #get the modified date with dashes replaced by underscores
    printf $(stat --printf %y "$f" | cut -d" " -f1 | tr '-' '_') 
    printf "_calif_"
    printf $COUNTER
    printf "."
    printf $SUFFIX
    let COUNTER=COUNTER+1
  #add a carriage return
  echo ""
  done
  

This outputs text like the following:

mv 00003.MTS 2017_04_12_calif_1.MTS
mv 00004.MTS 2017_04_12_calif_2.MTS
mv P1010781.JPG 2017_04_11_calif_3.JPG
mv P1010782.JPG 2017_04_11_calif_4.JPG
mv P1010783.JPG 2017_04_11_calif_5.JPG
...
...
  

Which we can pipe into a file and review before running. As I have made plain before, I often prefer the simple and naive way of doing things for the benefit of later comprehension. If you put together some complex arrangement of commands on a single line, it may be impressive but also difficult to maintain.