prune_dir.sh

#!/bin/bash
#
#  prune_dir - prune directory by deleting files if we are low on space
#
DIR=$1
CAPACITY_LIMIT=$2

if [ "$DIR" == "" ]; then
    echo "ERROR: directory not specified"
    exit 1
fi

if ! cd $DIR; then
    echo "ERROR: unable to chdir to directory '$DIR'"
    exit 2
fi

if [ "$CAPACITY_LIMIT" == "" ]; then
    CAPACITY_LIMIT=95 # default limit
fi

CAPACITY=$(df -k . | awk '{gsub("%",""); capacity=$5}; END {print capacity}')

if [ $CAPACITY -gt $CAPACITY_LIMIT ]; then
    # Get list of files, oldest first.
    # Delete the oldest files until we are below the limit.
    # Just delete regular files, ignore directories.
    find $DIR -type f -iregex ".*.\(mp4\|jpg\|png\|log\|json\|m4a\|aac\|flac\|mp3\|ogg\|opus\|wav\|mka\|mkv\|mpg\|ogv\|ts\|wma\|wmv\|webm\|part\|ytdl\|ffmpeg\.txt\)$" -print0 | xargs -0 ls -tr | while read FILE; do
        if rm -f "$FILE"; then
            echo "Deleted $FILE"

            CAPACITY=$(df -k . | awk '{gsub("%",""); capacity=$5}; END {print capacity}')

            if [ $CAPACITY -le $CAPACITY_LIMIT ]; then
                # we're below the limit, so stop deleting
                exit
            fi
        fi
    done
fi