Connecting a Bluetooth printer to Linux Mint

The following is how to connect a Bluetooth printer. The key is using a Manual URI with the MAC address without semicolons as the hostname.

Easy when you know how.

This give a good summary of the bluez-tools:

root@Spectre ~ # rfkill list
lists the various adapters, including hci0

root@Spectre ~ # hcitool scan
lists the various devices available, including H470. Note its MAC address:
The AppSocket protocol (sometimes also called the JetDirect protocol, owing to its origins with the HP JetDirect network interfaces) is the simplest, fastest, and generally the most reliable network protocol used for printers. AppSocket printing normally happens over port 9100 and uses the socket URI scheme:

This was the solution:

Kicker → Printers → Add Printer → Select a Printer to Add → Manual URI → Connection →

There are O-rings and then there are Oh!-rings…


The faucets are apparently Italian. Very intricate O-ring valve assembly. The brand appears to be something like Elli Roma.

There is a main shaft with three holes: hot cold, and spout.

The water is mixed and flows to the spout hole and from there into a channel around the shaft at the height of the spout inlet. There is a corrugated O-ring above and below the channel to prevent leakage.

Today it started leaking.

We could not find an exact replacement.

So we took two regular O-rings:

• 30 mm i.d., 3 mm thickness
• 30 mm i.d., 2.5 mm thickness

and put them in the channel for one of the corrugated O-rings and repeated for the other.

It works!


Transition Evolution to a new installation

We recently converted the operating system from openSUSE Leap 42.2 to Linux Mint (8) KDE. Doing so required transfering our Evolution data to the new OS.

We keep the Evolution data on a separate partition (/data/comms/internet/evolution) so that it doesn’t get corrupted by a system change. We then link the appropriate elements of that data to the default locations under /home/user/.

The best method is to use File→Backup/Restore. This writes the data (messages, contacts, etc.—but not the configuration files) to a tar.gz file. It You can restore from that file and then copy (write-into) any other message files you may have that were not in the backup tree.

However, restore will restore to /home/user/, not /data/comms/internet/. So we use an external program (LuckyBackup) to backup
to an external medium. Restoration is simply a matter of reconstructing the links from


There are two links that must be constructed when restoring:
man ln:
ln [OPTION]... TARGET... DIRECTORY (3rd form)
In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.

The configuration files:
 ln -s /data/comms/internet/evolution/ /home/user/.config/

This links the configuration files. .config does not contain the message tree, so ignores them:
The message tree:
   ln -s /data/comms/internet/evolution /home/user/.local/share/

This links the message tree to its proper home in

Ensure that you give the LuckyBackup enough time when backing up separately:
It builds the tree quickly but takes time to transfer the messages. You end up with an empty tree if you don’t give it enough time.

==== Background ====


Evolution format changed from 2.32 to 3.x. In both cases, the data was stored in ~/.local/share/evolution/mail/local/ according to XDG Base Directory Specification ( Inside that data directory, the format and the tree structure changed.

The 3.x format

In Evolution 3.x, the emails were stored in Maildir instead of Mbox format.

In Maildir format, a mail folder is composed of one directory (often called Maildir in Linux) containing 3 subdirectories called cur, new, and tmp. The subdirectory cur contains one file for each email of the folder, i.e., one file per email instead of one file containing all emails as in Mbox format.

File structure

This is the top level file structure of



This is the structure of the mail folder

The folders folder contains an xml file for each folder

The .local folder contains a directory tree mirroring the files in folders:

Each topic branch has three sub-branches (cur, new, tmp). cur contains the actual messages:

The program seems to be self-healing: when you leave the directory it reconstructs the index and any missing message
headers have been removed.

Chromium video playback [Solved]

We were unable to view video in Chromium
Version 54.0.2840.100 (64-bit)
Linux openSUSE 42.1.

The solution is here:
in Chromium.

Override software rendering list Mac, Windows, Linux, Chrome OS,
 AndroidOverrides the built-in software rendering list and
 enables GPU-acceleration on unsupported system configurations.

Restart Chromium.

Problem solved.

But then we could not open some websites:

We had downgraded Chromium to v54.0 from v56.0 to allow chromium-ffmpegsumo so that we could play videos. But that broke SSL certificates derived from Symantec:!topic/chrome/YLX1__NgPj0

Most of the reports here are to running an old and out-of-date Chromium v. 53 on Linux distros. Specifically this error will happen when using out of date Chrome/Chromium to go to secure websites who use SSL security certificates issued by Symantec or Symantec associated groups, including GeoTrust, Thawte, and VeriSign.

Craig’s list:
Issuer: GeoTrust SHA256 SSL CA

zypper se -s chromium-ffmpeg
It only returns chromium-ffmpegsumo.

We reupgraded to v.56 and now everything works.

Twilight zone…