This isn’t so much a question of how, as it is an expression of bafflement at the utter lack of tooling to do this.

opustag can set, delete, or add a single or multiple tags… but it can’t get a single tag. Same with ffmpeg. In fact, there appears to be not a single tool that can be used to get only the value of a single tag.

Sure, you can grep, but once tags start having multi-line values, this gets more complicated and error prone, and turns into a script. I honestly can’t believe that I have to write a program to query a single tag value. This isn’t even a Unix philosophy “do one thing well” issue; it’s clearly in opustag’s bailiwick.

Does anyone familiar with the spec know why this would be omitted from the opustag functionality? Is it, like, hard to query a single value, but easy to set it? Or is it just laziness? It can’t just be a gross omission, can it? What sane person would consider this an edge case user feature? There must be some rationale behind it, especially since, while there are multiple ways to set values, there appears to be not a single tool that can read a single key. Maybe reading is NP-hard in opus metadata?