Change file's numbers Bash

Question

I need to implement a script (duplq.sh) that would rename all the text files existing in the current directory using the command line arguments. So if the command duplq.sh

Answer 1

A possible solution...

#!/bin/sh

NUMBERS=$(ls $1|sed -e 's/pic//g' -e 's/\.txt//g'|sort -n -r)

for N in $NUMBERS
do
    NEW=$(($N + 3))
    echo "pic$N.txt -> pic$NEW.txt"
    mv "pic$N.txt" "pic$NEW.txt"
done