[SOLVED] old thumbnails can't be removed

In "~/.cache/thumbnails/" there are two directories: "fail/mate-thumbnail-factory" and "normal" that hold thumbnails. I've got a handful of old thumbnails that are somehow "stuck" in these directories from at least as far back as 2013. I've deleted them numerous times, but they reappear after each boot. Where are they even coming from? They're like ghosts. How do I remove them permanently?

I'm using Debian Buster at the moment, but they have been there since perhaps Sarge.

Bob

Thumbnail images are often not provided, but generated form the full sized images. If you have something that uses those images and generates the thumbnails it might need whenever they are missing, this might be so explained. If this is the case, then figuring out what is generating the thumbnails and uninstalling to would certainly stop that process. Is that worth the doing?

Originally Posted by wpeckham Thumbnail images are often not provided, but generated form the full sized images. If you have something that uses those images and generates the thumbnails it might need whenever they are missing, this might be so explained. If this is the case, then figuring out what is generating the thumbnails and uninstalling to would certainly stop that process. Is that worth the doing?

I'll have to see if I can figure out where they are coming from, then. I can sort of understand why the thumbnail of my granddaughter, but it's a mystery why the rest of the photos weren't thumbnailed. Also, the thumbs clearly aren't all from the same directory. One is a thumbnail of the output of Timelab. But I'll look into it from that POV and see what I can find. Maybe I should start by trying to find the Timelab file.

Bob

Originally Posted by Quakeboy02 In "~/.cache/thumbnails/" there are two directories: "fail/mate-thumbnail-factory" and "normal" that hold thumbnails. I've got a handful of old thumbnails that are somehow "stuck" in these directories from at least as far back as 2013. I've deleted them numerous times, but they reappear after each boot. Where are they even coming from? They're like ghosts. How do I remove them permanently?

This a pet peeve of mine: zillions of thumbnails.

You likely can't remove them permanently. If you've removed them and they return, something is, obviously, recreating them. A permanent solution would likely require that you stop using whatever program is creating them. (In my case, I suspect that Dolphin is the culprit but I can't realistically stop using that.)

It'd sure be nice there was some "structure" underneath that thumbnails subdirectory so you could at least identify what process is responsible for their return. Without that, the best you might be able to do is look at the timestamps on the thumbnails and determine what might have run at that time of day.

If the thumbnails are bogging down, say, a home directory tree backup, you can probably instruct that process to ignore the thumbnail directory and any others that contain information you don't need to be included. (E.g., "rsync(1)" has such an option.)

HTH...

There is some option in dconf that I turned off that got rid of most of the problem. I believe the only thumbnailer left running is /usr/bin/evince-thumbnailer. Unfortunately, you can't delete evince without deleting gnome. So, I tried just deleting /usr/bin/evince-thumbnailer yesterday. That was a step too far, and there were no longer any thumbnails. During my research on this yesterday, I came across a site that called these directories "shellbags for Linux" and went on to explain that they are often used for forensic analysis. I'm having trouble understanding why Linux would stoop to this level of snooping on their customers. But, this probably isn't the place to fully express my feelings on that. With the speed of today's processors and disks, thumbnails on the fly would not be a burden on most (any?) modern systems. When I get some free time later, I'm going to see if I can find any of the files the thumbs are generated from. With hundreds of GBs of data to scour, that may be a bit difficult.

Bob

UPDATE: It appears now that the ones I saw were just the first ones to populate the directories. As the day goes on, many, many files are added. So, I decided to just add a 5-minute cron job to remove them all in both directories. Time will tell whether this causes a problem.

Originally Posted by Quakeboy02 During my research on this yesterday, I came across a site that called these directories "shellbags for Linux" and went on to explain that they are often used for forensic analysis. I'm having trouble understanding why Linux would stoop to this level of snooping on their customers.

I don't think there's anything nefarious going on despite what the site you read claimed. In general, the thumbnails are simply an aid to let you see in miniature what graphics files represent. Forensic analysis? I suppose someone could browse through the thumbnails directory/tree and find evidence that images once existed on one's hard drive. (I doubt the thumbnails are deleted when the original, full-sized image is deleted.)

I like your idea of the cron job to clean out thumbnails. I think I'd limit it to a.) once a day and b.) deleting the thumbnails that were created more than N days ago.

On the bright side, at least thumbnails nowadays are mostly getting dumped into a centralized location. It could be worse. Back in the days when "xv" was the graphical file viewer of choice on Linux, it left hidden subdirectories containing thumbnails all over your filesystems---wherever you happened to execute it, there was another subdirectory created by xv.