createfs

#!/bin/bash

FOLDER="fs"
VOLUME_LABEL="REDACTED OS"
IMAGE=disk.img

if ! command -v "mcopy" >/dev/null 2>&1; then
    echo "Error: this script depends on mtools. Please install it" >&2
    exit 1
fi

if ! command -v "mkfs.fat" >/dev/null 2>&1; then
    echo "Error: this script depends on dosfstools. Please install it" >&2
    exit 1
fi


if [[ "$OSTYPE" == "darwin"* ]]; then
  SIZE_KB=$(du -sk "$FOLDER" | cut -f1)
else
  SIZE_KB=$(du -s -B1 "$FOLDER" | awk '{print int($1/1024)}')
fi

power_of_two() {
    local n=$1
    local p=1
    while (( p < n )); do
        (( p *= 2 ))
    done
    echo $p
}

SIZE_MB=$(( (SIZE_KB * 12 / 10 + 1023) / 1024 ))

SIZE_MB=$(power_of_two "$SIZE_MB")

if ((SIZE_MB < 64)); then
    SIZE_MB=64
fi

dd if=/dev/zero of=$IMAGE bs=1M count=$SIZE_MB

mkfs.fat -F 32 -n "$VOLUME_LABEL" $IMAGE

mcopy -i $IMAGE -s "$FOLDER"/* ::