Rename files in year directories

rename.sh

#!/usr/bin/env bash

# Custom move command that will create the destination directory if it does not
# exist.
function my_mv() {
  # If two arguments were passed and the first argument was a file that exists
  if [[ $# == 2 && -e $1 ]]
  then
    # Get the directory name of the second argument ("testing/test.txt" ->
    # "testing")
    local dir=$(dirname $2)
    # If the directory does not exist...
    if [[ ! -d $dir ]]
    then
      # ...make it...
      mkdir -p $dir
    fi
    # ...then move the file into it.
    mv $1 $2
  fi
}

# Get the current directories in root (the subject directories).  These will be
# deleted after the script runs.
subjects=$(ls -1 -d */)

# Loop through all files and move them
for file_a in $(find .)
do
  # Match files which have a './subject/year/month/filename' pattern
  if [[ $file_a =~ ^\./([^\.].*)/([0-9]{4})/[0-9]{1,2}/([^/]+)$ ]]
  then
    # Get the subject, year, and name from the regular expression match
    subject=${BASH_REMATCH[1]}
    year=${BASH_REMATCH[2]}
    name=${BASH_REMATCH[3]}

    # Create the new file name
    file_b="./$year/$subject/$name"

    # Do the renaming
    echo "Renaming $file_a to $file_b ..."
    my_mv $file_a $file_b
  fi
done

# Remove subject directories in root.  Unless you're totally sure what you're
# doing, leave this commented out and delete those subject folders manually.
# You'll be very unhappy if you run this script in the wrong folder.

# rm -rf $subjects