add character to the middle of a file name

Question

I need to add a character to the middle of a file name, I need to do this for about 8000 files all in the same directory. I'm looking for a command-line option:

Example (all files that need renaming are five digits, they are in a directory that contains other six-digit filenames that do not need to be renamed):

01011
02022
12193

To:

010101
020202
121903

I've tried a couple of things: rename, mv, etc. Similar to this (Bash - Adding 0's in the middle of a file name) but not exactly

Answer 1

You can write:

for file in * ; do
    mv ./"$file" "${file:0:4}0${file:4}"
done

(See the explanation of ${parameter:offset} and ${parameter:offset:length} in §3.5.3 "Shell Parameter Expansion" of the Bash Reference Manual.)

Edited to add: If you only want to capture a specific subset of files, you can change * to a more-specific pattern such as [0-9][0-9][0-9][0-9][0-9] (which matches filenames consisting of five digits).

Incidentally, you can format the whole thing on one line:

for file in [0-9][0-9][0-9][0-9][0-9] ; do mv "$file" "${file:0:4}0${file:4}" ; done

Answer 2

Try using below code.

rename -v -n "s/(S01S0[0-2][0-9])/\$1-/" *

-n to check the command output.