Run AppImage container

appimage.sh

#!/bin/bash
# Run AppImage container
set -e

function _mount {
    local target
    target="$(mktemp --tmpdir --directory appimage.XXXXXXXXXX)"
    /bin/mount --types squashfs -o offset="${2:-0}" --read-only -- "${1}" "${target}"
    echo "${target}"
}

function _unmount {
    /bin/umount -- "${1}"
    rmdir "${1}"
}

function squashfs_offset {
    # Get offset from runner
    PATH="${PATH}:${PWD}" /sbin/runuser -u "${USER}" -- "${APP}" --appimage-offset

    # Alternatively we can sniff the AppImage
    # Squashfs magic: 0x73717368 (i.e. "hsqs" little-endian)
    #grep -obUa 'hsqs' "$1" | tail -n 1 | cut -d : -f 1 -
}


if [[ $# -lt 1 ]]; then
    echo >&2 'Usage: <appimage> <arg>...'
    exit 1
fi

if [[ "${EUID}" -ne 0 ]]; then
    # Must run as root
    exec /usr/bin/sudo "$0" "$@"
fi

USER="${SUDO_USER:-root}"
APP="$1"
APPNAME="$(basename "${APP}")"
APPRUN=./AppRun
OFFSET="$(squashfs_offset "${APP}")"

# Mount app
TARGET="$(_mount "${APP}" "${OFFSET}")"
trap "_unmount \"\${TARGET}\"" EXIT

# Run app
shift
(
    cd "${TARGET}"
    /sbin/runuser -u "${USER}" -- "${BASH}" -c "exec -a "${APPNAME}" \"\$@\"" -- "${APPRUN}" "$@"
)