Updater script for filemanager

update-filemanager.sh

#!/bin/bash

function currentverinstalled {
    if [ ! -f .fmver ]; then
        LINE=0
    else
        LINE=$(head -n 1 .fmver)
    fi
    LINE="${LINE//.}"
    echo "${LINE//v}"
}

function getcurrentghver {
    echo $(curl -s https://api.github.com/repos/hacdias/filemanager/releases/latest | python -c "import sys, json; data = json.load(sys.stdin); print(data['tag_name'])")
}

function lowercase {
    echo $1 | tr "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz"
}

function getostype {
    echo "$(lowercase $(uname -s))"
}

function getoshardware {
    case "$(uname -m)" in
        i686)
            echo "386"
            ;;
        x86_64)
            echo "amd64"
            ;;
        *arm*)
            echo "arm"
            ;;
        *)
            echo "Error: Unrecognized architecture."
            exit 1
            ;;
    esac
}

function determineifwindows {
    case "$(uname -s)" in
        *CYGWIN*)
            echo ".exe"
            ;;
        *)
            echo ""
            ;;
    esac
}

function formatassetname {
    echo "$(getostype)-$(getoshardware)-filemanager$(determineifwindows)"
}

function checkupdate {
    if [ "$1" = "check" ]; then
        echo "Checking for update..."
    fi

    CURINVER=$(currentverinstalled)
    CURGHVER=$(getcurrentghver)

    CLEANGHVER="${CURGHVER//.}"
    CLEANGHVER="${CLEANGHVER//v}"

    if [ $CURINVER -lt $CLEANGHVER ]; then
        UPDATE=0
    else
        UPDATE=1
    fi

    case "$1" in
        check)
            if [ $UPDATE -eq 0 ]; then
                echo "There is an update to $CURGHVER available."
            else
                echo "There is no update available."
            fi
            ;;
        update)
            echo $UPDATE
            ;;
        *)
            echo "Error: Could not determine update status."
            ;;
    esac

}

function runupdate {
    UPDATEAVAILABLE=$(checkupdate "update")
    if [ $UPDATEAVAILABLE -eq 1 ]; then
        echo "No updates are available."
        exit 0
    else
        echo "Update found."
    fi

    echo "Installing update..."

    ASSETNAME=$(formatassetname)

    UPDATEURL=$(curl -s https://api.github.com/repos/hacdias/filemanager/releases/latest | python -c "import sys, json; data = json.load(sys.stdin); myasset = [asset for asset in data['assets'] if asset['name'] == '$ASSETNAME'][0]; print(myasset['browser_download_url'])")

    wget -q $UPDATEURL -O "filemanager"

    echo $(getcurrentghver) > .fmver

    chmod +x "filemanager"

    echo "Update installed."

    exit 0
}

case "$1" in
    check)
        checkupdate "check"
        ;;
    update)
        runupdate
        ;;
    *)
        echo "Usage: install {check|update}"
        echo ""
        echo "  check       Checks if on latest version."
        echo "  update      Updates to latest version if available."
        ;;
esac