Helper script to mount/unmount mtp (Android et. al.) devices

mtpmnt

#!/bin/sh

set -euo pipefail

usage() {
  local basename
  basename="$(basename "$0")"
  cat <<DOC
Usage:
 $basename [options] [mount|unmount] [mtp_device_number]

Mount an mtp device using simple-mtpfs, or unmount with fusermount.
If no command is given, available device numbers and names are listed.
If no number is given, all devices are mounted or unmounted.

Mount points are created in \$HOME/Desktop and named after the device.
If a device name has multiple words, only the first word is used.

Options:
 -h, --help                      Display this help and exit.
 -b dirname, --basedir dirname   Use dirname as the base of mountpoints.

See simple-mtpfs (1), fusermount (1), mountpoint (1)
DOC
  exit 127
}

basedir="$HOME/Desktop"
case ${1:-} in
  -h | --help)
    usage
    ;;
  -b | --basedir)
    basedir="${2:-}"
    if [ -z "$basedir" ]; then
      printf %s\\n "Parameter required for basedir argument." >&2
      exit 1
    fi
    shift 2
    ;;
esac

dev=$(simple-mtpfs --list-devices)
if [ ! $? ]; then
  # Something went wrong with the device query.
  printf %s\\n "$dev" >&2
  exit 1
elif [ -z "${1:-}" ]; then
  # No command; list devices and quit.
  printf %s\\n "$dev"
  exit 0
fi

mode="${1:-}"
dev_num="${2:-}"
errors=

dev_name_from_num() {
  # Pass the device number; return the first word of the device name.
  local dev_name="$1"
  printf %s\\n "$dev" | sed -nr -e "/^$dev_name:\s+(\S+).*/{s//\1/p;q}"
}

do_mount() {
  local dev_num="$1"
  local mountpoint="$basedir/$2"
  if [ -z "$2" ]; then
    printf %s\\n "There is no device $1 to mount." >&2
    errors=1
    return
  fi
  if mountpoint --quiet "$mountpoint"; then
    printf %s\\n "$mountpoint is already a mountpoint." >&2
    errors=1
    return
  fi
  [ ! -d "$mountpoint" ] && mkdir "$mountpoint"
  if simple-mtpfs --device "$dev_num" "$mountpoint"; then
    printf %s\\n "Mounted $mountpoint"
  else
    printf %s\\n "Failed to mount $mountpoint" >&2
  fi
}

do_unmount() {
  local dev_num="$1"
  local mountpoint="$basedir/$2"
  if [ -z "$2" ]; then
    printf %s\\n "There is no device $dev_num to unmount." >&2
    errors=1
    return
  fi
  if ! mountpoint --quiet "$mountpoint"; then
    printf %s\\n "$mountpoint is not a mountpoint." >&2
    errors=1
    return
  fi
  if fusermount -u "$mountpoint"; then
    printf %s\\n "Unmounted $mountpoint"
    rmdir "$mountpoint"
  else
    printf %s\\n "Failed to unmount $mountpoint" >&2
  fi
}

case "$mode" in
  mount)
    do_cmd=do_mount
    ;;
  unmount|umount)
    do_cmd=do_unmount
    ;;
  *)
    printf %s\\n "Unknown mode '$mode'; use 'mount' or 'unmount'" >&2
    exit 1
    ;;
esac

if [ -z "$dev_num" ]; then
  # No number given; (un)mount all devices that were found earlier.
  while IFS=': ' read -r num name _; do
    $do_cmd "$num" "$name"
  done <<DEVS
$dev
DEVS
else
  # (Un)mount the given device number.
  $do_cmd "$dev_num" "$(dev_name_from_num "$dev_num")"
fi

# Somthing went wrong on at least one (un)mount attempt.
[ -n "$errors" ] && exit 2

exit 0