The Lemmington Post

To accomplish this task, we can use a combination of Bash scripting and various Linux utilities such as find, mv, du, and sort. Here's a step-by-step approach:

1. Create a bash script file, let's call it reorganize.sh.

#!/bin/bash

# Define the mount points and the desired free space threshold
declare -a MOUNT_POINTS=("/mnt/hdd0" "/mnt/hdd1" "/mnt/hdd2" ...)
FREE_SPACE_THRESHOLD=20  # In gigabytes

# Function to get the available space on a file system
get_available_space() {
    local mount_point="$1"
    df --output=avail "$mount_point" | tail -n 1 | awk '{print $1}'
}

# Create an associative array to keep track of the available space on each file system
declare -A AVAILABLE_SPACE
for mount_point in "${MOUNT_POINTS[@]}"; do
    AVAILABLE_SPACE["$mount_point"]=$(get_available_space "$mount_point")
done

# Function to find the mount point with the most available space
find_mount_point_with_most_space() {
    local max_space=0
    local max_mount_point=""

    for mount_point in "${!AVAILABLE_SPACE[@]}"; do
        if [ "${AVAILABLE_SPACE[$mount_point]}" -gt "$max_space" ]; then
            max_space="${AVAILABLE_SPACE[$mount_point]}"
            max_mount_point="$mount_point"
        fi
    done

    echo "$max_mount_point"
}

# Function to redistribute files based on alphabetical order
redistribute_files() {
    local source_dir="$1"
    local target_dir="$2"

    # Get a list of files sorted alphabetically by relative path
    local files=$(find "$source_dir" -type f | sort)

    # Move files to the target directory
    while read -r file; do
        local relative_path=$(realpath --relative-to="$source_dir" "$file")
        local file_size=$(du -k "$file" | cut -f 1)

        # Update available space on source and target directories
        AVAILABLE_SPACE["$source_dir"]=$((AVAILABLE_SPACE["$source_dir"] + file_size))
        AVAILABLE_SPACE["$target_dir"]=$((AVAILABLE_SPACE["$target_dir"] - file_size))

        mkdir -p "$target_dir/$(dirname "$relative_path")"
        mv "$file" "$target_dir/$relative_path"
    done <<< "$files"
}

# Function to move files from one file system to another if the free space is below the threshold
move_files_if_needed() {
    local source_dir="$1"
    local temp_dir=$(mktemp -d --tmpdir="$(find_mount_point_with_most_space)")

    if [ "${AVAILABLE_SPACE[$source_dir]}" -lt "$((FREE_SPACE_THRESHOLD * 1024 * 1024))" ]; then
        # If the available space on the source directory is below the threshold,
        # move the files to a temporary directory on the mount point with the most available space
        redistribute_files "$source_dir" "$temp_dir"
        rm -rf "$source_dir"/*
        # Move the files back to the source directory, preserving the alphabetical order
        redistribute_files "$temp_dir" "$source_dir"
        rmdir "$temp_dir"
    fi
}

# Main script
for ((i=0; i<${#MOUNT_POINTS[@]}; i++)); do
    local mount_point="${MOUNT_POINTS[$i]}"
    # Check if the current mount point needs to be cleared to meet the free space threshold
    move_files_if_needed "$mount_point"
    # Redistribute files from the current mount point to the remaining mount points in alphabetical order
    for ((j=i+1; j<${#MOUNT_POINTS[@]}; j++)); do
        redistribute_files "$mount_point" "${MOUNT_POINTS[$j]}"
    done
done

2. Save the script file and make it executable:

chmod +x reorganize.sh

3. Run the script:

./reorganize.sh