/dev/sda is the whole raw disk - you typically don’t want to directly interact with /dev/sda, unless you are partitioning or overwriting it. There are a few layers between that device and the files:

• raw disk - /dev/sda
• disk partition - /dev/sda1
• luks container - when unlocked, mapped to /dev/mapper/{name}
• ext4 filesystem inside the luks container, mounted somewhere like /mnt, /media, etc

You’ll need to find where that ext4 filesystem is mounted, and run the chown command on that. You can run lsblkand see a tree of the above hierarchy, with the ext4 filesystem’s mountpount shown in the right-hand column.

Ctrl+r was a life-changer when I first learned it.

I’d recommend a full battery calibration before running the command one more time, if you haven’t already (charge the battery fully, leave it on the charger at 100% for a while, then fully discharge until it shuts itself off, leave it for a bit, then fully recharge while off). If the calibrated values line up with a full:design ratio of ~80%, especially with a 10-year-old battery with almost 700 cycles on it, my take is that’s pretty great.

That said, I think the best way to get an accurate feel for the health of an old battery is to put it through one full cycle of normal use and time how long it takes to die.

If you’re genuinely worried about this, you shouldn’t be using untrusted machines for remote access.

Apache Guacamole might be a good option. “Clientless” (browser-based), supports various mfa, uses ssh/vnc/rdp on the backend.

However, if the data on that machine is sensitive, or if that machine has access to other sensitive things on your network, I’d suggest caution in allowing remote access from untrusted machines on the wider internet.

powertop is a cool tool that can analyze your machine and provide a list of suggested power optimizations

DNS is what you’re looking for. To keep it simple and in one place (your adguard instance), you can add local dns entries under Filters > DNS Rewrites in the format below:

192.xxx.x.47 plex.yourdomain.xyz
192.xxx.x.53 snapdrop.yourdomain.xyz

Can’t beat an X230 with an i5 for that use case, and you can still find them for around 100 bucks. Swap in an X220 keyboard, maybe a new battery, coreboot it, and in my opinion you’ve got the perfect laptop. I’ve daily driven that setup for the last 5 years and it’s been great.