Written 2 Sep 2026. This is a how-to, not a product card.

Peek at disk details with udevadm

After by-id shows hardware-style fixed names, use a look-only udevadm info on a disk path so you see the properties udev already knows - without mounting, formatting, or rewriting anything.

Linux keeps a small database of what each disk and stick looks like to the system. udevadm is the tool that can print that info. Tonight you only read. You don't trigger rules, settle devices, rewrite disks, or change fstab.

Skip until SSH works

If you cannot log in from the couch yet, stop. That is SSH from the couch. Disk details don't help a login that fails.

If you only need the list of disks and USB sticks, that is see disks and USB sticks (lsblk). If you only need which folders are already attached, that is see which folders are already attached (findmnt). If you only need labels and UUIDs printed as text, that is read disk labels and UUIDs (blkid). If you only need filesystem UUID paths, that is see stable disk names by UUID. If you only need hardware-style fixed names, that is see stable disk names by hardware id. If you only need room left on a path, that is see if the computer still has room (df).

What this is

udev is the part of Linux that notices when you plug in a disk or stick and sets up the short names under /dev (and the fixed folders under /dev/disk/by-uuid and /dev/disk/by-id). udevadm info prints what udev already knows about one device - look only.

Here is the one jargon split for tonight: lsblk and blkid show a friendly table or a short label/UUID line. udevadm info shows a longer property list (model, serial, bus, links). Same computer, deeper peek. Still no mount, format, or wipe.

Practice: peek at one disk

SSH in from the couch. Pick a name you already trust from lsblk or from by-id. Whole-disk examples often look like /dev/sda or /dev/nvme0n1. Then ask:

udevadm info /dev/sda

Swap /dev/sda for the name on the computer. You should see a block of lines - often starting with P: / N: / E: style fields - naming the device path, and many E: property lines (model, serial, filesystem hints when Linux knows them). In plain English: udev is showing the scrapbook it keeps for that disk.

Optional: use a stable by-id path instead of today’s letter (same look, fixed name):

udevadm info /dev/disk/by-id/ata-YOURDISK

Use a real name from ls /dev/disk/by-id on the computer. Don't invent one.

Optional: print only the property lines (a bit quieter):

udevadm info -q property /dev/sda

Home-safe look only. Don't format, wipe, remount, or edit fstab tonight.

Optional: after you plug in a USB for backup

Plug the stick into the computer. Run lsblk so you know today’s letter, then run udevadm info on that /dev/… name (or on the usb-… by-id path). You should see USB-ish properties and a serial. Compare with blkid if you want the filesystem UUID next. If you need the mount map, that is see which folders are already attached. The backup job, once a path is live, is a backup of the folder.

Useful extras, still a look

Skip udevadm trigger, udevadm settle, udevadm control, and rewriting udev rules as the lesson. Tonight you read of what udev already knows.

Skip mount and umount as the job. Skip rewriting disks, dd, shred, interactive fdisk, parted, format, or rewriting fstab. Those are not this note. A look-only partition table print is fdisk-list (fdisk -l).

Skip buying a NAS because a property line looks unfamiliar. Free room is disk-space. Disk names without tags are lsblk. Mount maps are findmnt. Printed labels and UUIDs are blkid. Filesystem UUID paths are by-uuid. Hardware-style fixed names are by-id.

Skip screen, tmux, and port 22 forwarding. Keep SSH on the house network: keep the computer on the house network.

Skip awk, sed, and install as new pages this cycle.

What this is not

This is not lsblk. That lists disks and USB sticks by name: see disks and USB sticks. It is not findmnt. That shows which folders are already attached: see which folders are already attached. It is not blkid. That prints LABEL, UUID, and TYPE as text: read disk labels and UUIDs. It is not by-uuid. That lists filesystem UUID paths under /dev/disk/by-uuid: see stable disk names by UUID. It is not by-id. That lists hardware-style names under /dev/disk/by-id: see stable disk names by hardware id. It is not disk-space (df). That shows how full a mounted path is: see if the computer still has room. It is not disk, which focuses on how big the main disk already is: see how big the disk already is. It is not USB-disk, a shorter “did the stick show up?” check: see if the USB backup disk showed up. It is not the backup copy itself: a backup of the folder.

What next

Want the partition table printout next? Peek at partition tables with fdisk (fdisk -l look only). Need hardware-style fixed names first? See stable disk names by hardware id. Need filesystem UUID paths? See stable disk names by UUID. Need labels and UUIDs printed? Read disk labels and UUIDs. Need the disk-name list? See disks and USB sticks. Need which folders are already attached? See which folders are already attached. Need room left on a path? See if the computer still has room. Stick visible and ready for a second copy? A backup of the folder. Need how big the main disk already is? See how big the disk already is. Keep SSH on the house network: keep the computer on the house network. awk, sed, and install stay deferred this cycle.

Skip

• Skip if SSH still fails. Finish SSH from the couch first.
• Skip lsblk, findmnt, blkid, by-uuid, by-id, disk-space, or total disk size as tonight's job if you only came for the look-only udevadm info peek. Those notes already exist.
• Skip udevadm trigger / settle / control and rewriting udev rules as the lesson.
• Skip mount/umount as the lesson, and skip rewriting disks, dd, shred, fdisk, parted, format, and rewriting fstab.
• Skip buying a NAS because a property line looks unfamiliar.
• Skip awk/sed/install as new pages this cycle, screen, tmux, and port 22 forwarding.
• Skip opening SSH to the internet. That is keep the computer on the house network. Don't forward port 22.