Rename all files with the name pattern *.[a-z0-9].bundle.*, to replace the [a-z0-9] with a given string

In pure bash regEx using the =~ variable (supported from bash 3.0 onwards)

#!/bin/bashstring_to_replace_with="sample"for file in *.jsdo    [[ $file =~ \.([[:alnum:]]+).*$ ]] && string="${BASH_REMATCH[1]}"     mv -v "$file" "${file/$string/$string_to_replace_with}"done

For your given input files, running the script

$ bash script.shinline.d41d8cd.bundle.js -> inline.sample.bundle.jsmain.6d2e2e89.bundle.js -> main.sample.bundle.js

Short, powerfull and efficient:

Use this (perl) tool. And use Perl Regular Expression:

rename 's/\.\X{4,8}\./.myString./' *.js

or

rename 's/\.\X+\./.myString./' *.js

A pure-bash option:

shopt -s extglob    # so *(...) will workgeneric_string="foo"   # or whatever else you want between the dotsfor f in *.bundle.js ; do    mv -vi "$f" "${f/.*([^.])./.${generic_string}.}"done

The key is the replacement ${f/.*([^.]./.${generic_string}.}. The pattern /.*([^.])./ matches the first occurrence of .<some text>., where <some text> does not include a dot ([^.]) (see the man page). The replacement .${generic_string}. replaces that with whatever generic string you want. Other than that, double-quote in case you have spaces, and there you are!

Edit Thanks to F. Hauri - added -vi to mv. -v = show what is being renamed; -i = prompt before overwrite (man page).