I like combining this with a bash implementation of an event API (https://github.com/bashup/events). This makes it easy/idiomatic, for example, to conditionally add cleanup as you go.
Thank you for sharing - if i understand the code, the queue is serialized into bash variable(s) (arrays)?
I must admit I find the code somewhat painfully terse and hard to read.
Still, interesting idea. I wonder if using a temporary SQLite/Berkeley DB/etc for queue might generalize the idea to a "Unix" event system - allowing other programs and scripts to use it for coordinating? (Like logger(1) does for logging)?
Yep. Definitely something you can do manually, but the API makes it easier to reason about and coordinate across otherwise disconnected/unrelated code.
Was thinking more as a "global" queue (like how psql/libpq will go look for a socket to local postgres in "the right place") - and a binary/program "event" could "magically" store ("on") and process ("emit") events in a db file /tmp/event.<namespace><random>.sqlite3 - creating/initializing or re-using db file as needed...
So keep the api, but support cross process queues, more or less.
Glossing over some complexity, but roughly:
I wrote a little about some other places where I've used it in https://www.t-ravis.com/post/shell/neighborly_shell_with_bas... and https://t-ravis.com/post/nix/avoid_trap_clobbering_in_nix-sh... (though I make the best use of it in my private bootstrap and backup scripts...)