How to rename files in bash to increase number in name?

Question

I have a few thousand files named as follows:

Cyprinus_carpio_600_nanopore_trim_reads.fasta                
Cyprinus_carpio_700_nanopore_trim_reads.fasta             


        

Answer 1

Considering the filename conflicts in the increasing order, I first thought of reversing the order but there still remains the possibility of conflicts in the alphabetical (standard) sort due to the difference to the numerical sort.
Then how about a two-step solution: in the 1st step, an escape character (or whatever character which does not appear in the filename) is inserted in the filename and it is removed in the 2nd step.

#!/bin/bash

esc=$'\033' # ESC character

# 1st pass: increase the number by 100 and insert a ESC before it
for f in *.fasta; do
    num=${f//[^0-9]/}
    num2=$((num + 100))
    f2=${f/$num/$esc$num2}
    mv "$f" "$f2"
done

# 2nd pass: remove the ESC from the filename
for f in *.fasta; do
    f2=${f/$esc/}
    mv "$f" "$f2"
done