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Nautilus: batch thumbnail generation for remote location

I have a fairly large photo collection on a raspberry pi based NAS. Unfortunately RPI ethernet port is not fast enough (100MB/s) for comfortable remote operation, so to be able to use that collection I have to keep local thumbnail directory on my linux box. Gnome nautilus is my tool of choice, but nautilus generates thumbnails only after entering a directory. To make that setup workable I had to:

1. Make sure gnome allows big thumbnails and doesn’t expire them: dconf-editor, go to org->gnome->desktop->thumbnail-cache and set maximum-age and maximum-size to -1

2. Generate the thumbnails

Nautilus thumbnails are saved in png files with name like this: 00067ecff5de0e48602327bc987f6d9a.png. The name is md5sum of image path with spaces replaced by %20.  The path is not an absolute path in the system! So for example I have a photo at /run/user/1000/gvfs/sftp:host=192.168.1.231,user=pi/mnt/PhotoArchive/Dump/a_photo.jpg, but the path nautilus uses to generate thumbnail name is sftp://pi@192.168.1.231/mnt/PhotoArchive/Dump/a_photo.jpg (it can be checked in nautilus – just right click on an image and check location). Local files have prefix file://

I had some problems with getting reliable results for a find command run on a remote system, so I decided to create 2 scripts to generate the thumbnails. The first script scans (scan.sh – BROKEN LINK) remote location for images, generates md5sum for the image path and, if there is no thumbnail stored locally, writes the file path to a pipe. Another script (thumbnail.sh –BROKEN LINK) waits for whatever shows up in the pipe and generates the thumbnail. An example usage:

./scan.sh /run/user/1000/gvfs/sftp:host=192.168.1.231,user=pi mnt/ sftp://pi@192.168.1.231

and in a separate terminal:

./thumbnail.sh /run/user/1000/gvfs/sftp\:host\=192.168.1.231\,user\=pi/ sftp://pi@192.168.1.231

Legend:

/run/user/1000/gvfs/sftp\:host\=192.168.1.231\,user\=pi/ <– I have my NAS mounted at that point ($ROOT_DIRECTORY)

mnt/ <–the scripts scan should scan that directory and all subdirectories ($IMAGE_DIRECTORY)

sftp://pi@192.168.1.231 <– path prefix used by nautilius for that location to generate md5sum ($PREFIX)

I used those 2 script to generate over 65.000 (6 GB) of thumbnails. The directory where thumbnails are saved is hardcoded in thumbnail.sh (THUMBNAIL_DIR=/home/przemo/.cache/thumbnails/large/) – please update before using the script!

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