Automount android phones. Uses go-mtpfs.

mtp-automount.sh

#!/bin/sh
# this script mounts and opens any connected mtp devices while it's running.
# requires go-mtpfs, moreutils , fuse and udev.

# config
cache="${XDG_CACHE_HOME:-$HOME/.cache}/mtpd"
tmp="${XDG_RUNTIME_DIR:-/tmp}/mtpd"

main()
{
    check_deps
    make_dirs
    udevadm monitor -ususb | while IFS= read -r dev; do
        case $dev in
            *' add '*|*' remove '*)
                # shellcheck disable=SC2086
                set -- $dev
                handle "$4" &
            ;;
        esac
    done &
    wait
}

handle()
{
    if is_connected "$1"; then
        mount "$1"
    else
        is_mounted "$1" && unmount_and_cleanup "$1"
    fi
}

mount()
{
    m="$(generate_mountpoint "$1")" || return 1
    c="$(generate_cachedir "$1")"   || return 1
    set_mounted "$1" "$m" "$c"
    TMPDIR="$c" go-mtpfs -dev=" $(get_serial "$1")$" "$m" 2>&1 |
        while IFS= read -r line; do
            case $line in
                *mounted*) setsid -f xdg-open "$m" >/dev/null 2>&1 ;;
            esac
        done
    is_mounted "$1" && unmount_and_cleanup "$1"
}

unmount_and_cleanup()
{
    mp="$(get_mountpoint "$1")"
    cd="$(get_cachedir "$1")"
    unmount "$mp"
    rmdir "$mp" 2>/dev/null
    rm -rf "$cd"
    awk -v dev="$1" '$1 != dev' "$table" | sponge "$table"
}

unmount()
{
    delay=2
    until fusermount -u "$1" 2>&1 | grep -Eq 'not found|(bad|invalid) mount'; do
        sleep $delay
        [ $delay -lt 120 ] && delay=$((delay+2))
    done
}

is_connected() { [ -r "/sys/$1/serial" ] ;}
is_mounted()   { cut -f1 "$table" | grep -qx "$1" ;}
set_mounted() {
    ( printf '%s\t%s\t%s\n' "$1" "$2" "$3"; cat "$table" ) | sponge "$table"
}

get_serial()       { cat "/sys/$1/serial" ;}
get_product_name() { tr ' \t' '_' < "/sys/$1/product" ;}
get_vendor_name()  { tr ' \t' '_' < "/sys/$1/manufacturer" ;}
get_mountpoint()   { awk -v dev="$1" '$1 == dev {print $2; exit}' "$table" ;}
get_cachedir()     { awk -v dev="$1" '$1 == dev {print $3; exit}' "$table" ;}

is_integer()          { [ "$1" -eq "$1" ] 2>/dev/null ;}
generate_cachedir()   { mktemp -d "$cache/XXXXXXXXXX" ;}
generate_mountpoint() {
    mktemp -d "$tmp/$(get_product_name "$1")-$(get_vendor_name "$1")-XXXXXX"
}

make_dirs()
{
    umask 077
    mkdir -p "$cache" || die failed making dir "$cache".
    mkdir -p "$tmp" || die failed making dir "$tmp".
    table="$(mktemp "$tmp/mtab-XXXXXXXXXX")" ||
        die failed making tmpfiles inside "$tmp".
}

check_deps()
{
    for prog in go-mtpfs fusermount udevadm sponge; do
        command -v $prog >/dev/null ||
            die "$prog not found. \
go-mtpfs, fuse, udev and moreutils are required for mtpd."
    done
    pidof -q udevd || die udevd is not running.
}

die()     { printf '%s\n' "mtpd: Error: $*"; exit 1 ;}
cleanup() { pkill -P$$; rm "$table"; rm -rf "${cache:?}"/* ;}

trap cleanup HUP INT TERM
main "$@"