Answer by ozzy for want to Rename Images In Bulk in Linux

In Bash, the solution could look like this:

#!/bin/bash

shopt -s extglob

for fn_old in *.jpg; do

  i=0
  fn_new=${fn_old##+([-0-9])}                       # strip leading number sequence in basename 
  fn_new=${fn_new/%[-0-9]*([-0-9x]).jpg/.jpg}       # strip trailing number sequence in basename

  while [[ -e $fn_new ]]; do                        # see if proposed name already exists
    i=$((i+1))                                      # doublure counter
    fn_new=${fn_new/%*([-0-9]).jpg/-$i.jpg}         # try new filename with updated number
  done

  echo "$fn_old" -- "$fn_new"
  mv   "$fn_old" "$fn_new"

done

Be careful with the mv command. You may want to comment it out (or replace it with a cp) on a first run, just to see if the renaming scheme is what you want/expect.

For an explanation of the shell patterns and string manipulations, see: Bash pattern matching and Bash string manipulations.