How to “find” both regular files and directories

Try this variant:

$ find /etc /srv \( -path /srv/tftp/pxelinux.cfg -o -path /etc/mtab \) \
    -prune -o -print

This will "prune" either of those 2 -path arguments from the list, and print everything else.

You should decompose your goal into several steps easier to solve. This will have two advantages:

• It will be easier to solve,
• The resulting code will be clearer and more reusable.

The scripts below basically follows these steps:

1. Generate raw statistic files. An easy way is to append the file size and the file name in a temporary file named after the original file extension. So, if you have the file /path/to/foo.mp3 which is 3000000 large, it will append 3000000 /path/to/foo.mp3 at the end of a temporary file named mp3.
2. Handle specific cases. Here it will process the temporary file m4a and create the two other files m4a_aac and m4a_alac based on the test you gave in the question.
3. Generate output. All the needed information being now available, it just has to:
   • Count the number of line in each temporary file to determine the number of file of this type,
   • Sum up each size to get the total size of files of this type.

Here is the script:

#!/bin/sh

# This script takes the searched directory as first parameter.
# For instance: ./this-script.sh ~/Music

: ${1:?"You must pass the search directory as first parameter."}
searchdir="$1"

# Create a temporary directory
statsdir=""
trap 'rm -rf $statsdir' EXIT
statsdir=$(mktemp -d "/tmp/tmp.XXXXXXXXXX") || exit 1

# Generate one listing file per extension
awkscript='/\.[[:alnum:]]+$/ {print $0 >statsdir"/"$(NF)}'
# For Linux: stat -c "%s %n"
# For Mac: stat -f "%z %N"
find "$searchdir" -type f -exec stat -f "%z %N" {} + | \
    awk -F '.' -v statsdir="$statsdir" "$awkscript"

# Distinguish between m4a/AAC and m4a/ALAC
if [ -f "$statsdir/m4a" ]; then
    input="$statsdir/m4a"
    while IFS= read -r line; do
        filename=${line#* }
        if avprobe "$filename" 2>&1 | grep -q 'Audio: alac'; then
            echo "$line" >> "$statsdir/m4a_alac"
        else
            echo "$line" >> "$statsdir/m4a_aac"
        fi
    done < "$input"
    rm "$statsdir/m4a"
fi

# Generate and display result
{
    printf "Type Count Size\n"
    for extension in $(ls "$statsdir"); do
        count=$(wc -l "$statsdir/$extension" | cut -d ' ' -f 1)
        totalsize=$(awk '{s+=$1} END {print s}' "$statsdir/$extension")
        printf "%s %d %d\n" "$extension" "$count" "$totalsize"
    done
} | column -t