Custom action to set emblem in thunar [duplicate]

Solution 1:

Thunar saves its metadata in a special file. You can find it at $HOME/.cache/Thunar/metafile.tbd.

This is a database and can be accessed using tbdtool (that is part of tdb-tools)

Use it like this:

tdbtool $HOME/.cache/Thunar/metafile.tdb

To show the contents of the database use the dump command.

dump
Dump the current database as strings.

In your question you also wanted to insert emblems. You can use insert for this:

insert KEY *DATA*
Insert a record into the current database.