Move files to subfolders based on part of their filename

Question

I have files with filenames such as:

text_2_2022-11-22_K03_10k_66_P578_B06_2999dl_text_693_coff_442.jpg text_2_2022-11-22_K03_10k_66_P578_B06_2999dl_text_693_coff_432.jpg text_2_2022-11-22_K05_10k_66_P578_B06_2999dl_text_693_coff_175.jpg text_2_2022-11-22_K05_10k_66_P578_B06_2999dl_text_693_coff_832.jpg text_2_2022-11-22_K08_10k_66_P578_B06_2999dl_text_693_coff_322.jpg text_2_2022-11-22_K08_10k_66_P578_B06_2999dl_text_693_coff_975.jpg

I want to create subfolders like:

K03_10k_66_P578_B06
K05_10k_66_P578_B06
K08_10k_66_P578_B06

and then move the files to the correct subfolder.

Other answers use parameter expansion but I could not figure out to do this given the more complex names. Therefore I wrote a grep/regex command that matches the needed part of the filename but could not implement it in a loop:

grep '[A-Z][0-9]*_[0-9]*[a-z]_[0-9]*_[A-Z][0-9]*_[A-Z][0-9]*'

I have found similar answers (1 2 3 4) to my question but my filenames are more complex than in those questions.

Answer 1

This worked for me in bash using parameter expansion, splitting filename into parts, re-joining a slice of the parts into the subfolder name:

# get list of .jpg files to work on
shopt -s nullglob
file_list=( *.jpg )

# quick exit if there are no files
[[ ${#file_list[@]} -lt 1 ]] && {
  echo 'No *.jpg files found' >&2
  exit 1
}

# handle each file in the list
for orig_fname in "${file_list[@]}"
do
  # get filename without .xyz suffix
  fname="${orig_fname%.*}"

  # split file name into parts on underscores
  IFS=_ fname_parts=( $fname )

  # join parts 3,4,5,6,7 into the subfolder name
  # note: includes trailing _ in name
  printf -v subfolder '%s_' "${fname_parts[@]:3:5}"
  subfolder="${subfolder%_}"  # strip trailing _ from name

  # create subfolder if needed
  mkdir -v -p "$subfolder"

  # move file to its subfolder
  mv -v "$orig_fname" "$subfolder"
done

Remove the -v from the mkdir and mv commands if you don't want their info to scroll on your screen.