I made my first android app today. It was terrible and I plan to never do it again.

It took me about three hours of trying to get the sample apps to run before I gave up and made something from scratch. Both involved heavy use of ChatGPT (not my usual flow).

That said, if you want an app that reminds you how to tie your tie in an easy step-by-step way, you can download the APK from my website, and I believe you should be able to run that on your phone.

I don't know how to easily share Android source code, so I won't.

In a previous post I discussed how to backup android with rsync. In this post, I’ll improve on that solution so it happens when you plug the phone in, rather than manually. My solution happens to know I have only one phone; you should adjust accordingly.

The process is

1. Plug the phone in
2. Unlock the screen (you’ll see a prompt to do this).
3. Backup starts automatically
4. Wait for the backup to finish before unplugging

First, let’s add a udev rule to auto-mount the phone when it’s plugged in and unlocked, and run appropriate scripts.

# 10-android.rules
ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4ee2", MODE="0660", GROUP="plugdev", SYMLINK+="android", RUN+="/usr/local/bin/android-connected"
ACTION=="remove", SUBSYSTEM=="usb", ENV{ID_MODEL}=="Nexus_4", RUN+="/usr/local/bin/android-disconnected"

Next, we’ll add android-connected and android-disconnected

#!/bin/bash
# /usr/local/bin/android-connected
if [[ "$1" != "-f" ]]
then
 echo "/usr/local/bin/android-connected -f" | /usr/bin/at now
 exit 0
fi

sudo -u zachary DISPLAY=:0 /usr/bin/notify-send "Android plugged in, please unlock."
sudo -u zachary /usr/local/bin/android-mountfs
sudo -u zachary DISPLAY=:0 /usr/bin/notify-send "Mounted, backing up..."
/usr/bin/flock /var/lock/phone-backup.pid sudo -u zachary /usr/local/bin/phone-backup-xenu
sudo -u zachary DISPLAY=:0 /usr/bin/notify-send "Backup completed."

# !/bin/sh
# /usr/local/bin/android-disconnected
#!/bin/sh
sudo -u zachary DISPLAY=:0 /usr/bin/notify-send "Android unplugged."
sudo -u zachary /usr/local/bin/android-umountfs

We’ll add something to mount and unmount the system. Keeping in mind that mounting only works when the screen is unlocked we’ll put that in a loop that checks if the mount worked:

#!/bin/sh
# /usr/local/bin/android-mountfs

android_locked()
{
ls /media/android 2>/dev/null >/dev/null
[ "$?" -eq 2 ]
}

jmtpfs /media/android # mount
while android_locked; do
  fusermount -u /media/android
  sleep 3
  jmtpfs /media/android # mount
done

#!/bin/sh
# /usr/local/bin/android-umountfs
fusermount -u /media/android

The contents of  /usr/local/bin/phone-backup are pretty me-specific so I’ll omit it, but it copies /media/android over to a server. (fun detail: MTP doesn’t show all information even on a rooted phone, so there’s more work to do)

Edit: See here for an automatic version of the backup portion.

Connecting android to Windows and Mac, pretty easy. On arch linux? Major pain. Here’s what I did, mostly via the help of the arch wiki:

1. Rooted my phone. Otherwise you can’t back up major parts of the file system (including text messages and most application data) [EDIT: Actually, you can’t back these up over MTP even once you root your phone. Oops.]
2. Installed jmtpfs, a FUSE filesystem for mounting MTP, the new alternative to mount-as-storage on portable devices.
3. Enabled ‘user_allow_other’ in /etc/fuse.conf. I’m not sure if I needed to, but I did.

4. Plugged in the phone, and mounted the filesystem:

   jmtpfs /media/android
   

   The biggest pitfall I had was that if the phone’s screen is not unlocked at this point, mysterious failures will pop up later.

5. Synced the contents of the phone. For reasons I didn’t diagnose (I assume specific to FUSE), this actually fails as root:

   rsync -aAXv --progress --fake-super --one-file-system /media/android --delete --delete-excluded "$SYNC_DESTINATION"