Bash function to convert bytes to human readable size

human_readable.sh

# Copyright 2015 Andrew Gunnerson <[email protected]>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


# Convert bytes to human readable size
# $1: Size in bytes
# $2: Floating point precision (digits after dot)
# Return: Nothing
# Prints: Human readable size
#
# Example: "$(human_readable 6390759424 2)" == "5.95 GiB"
human_readable() {
    local abbrevs=(
        $((1 << 60)):ZiB
        $((1 << 50)):EiB
        $((1 << 40)):TiB
        $((1 << 30)):GiB
        $((1 << 20)):MiB
        $((1 << 10)):KiB
        $((1)):bytes
    )

    local bytes="${1}"
    local precision="${2}"

    if [[ "${bytes}" == "1" ]]; then
        echo "1 byte"
    else
        for item in "${abbrevs[@]}"; do
            local factor="${item%:*}"
            local abbrev="${item#*:}"
            if [[ "${bytes}" -ge "${factor}" ]]; then
                local size="$(bc -l <<< "${bytes} / ${factor}")"
                printf "%.*f %s\n" "${precision}" "${size}" "${abbrev}"
                break
            fi
        done
    fi
}