Thus, if the same service gets started 5 times iteratively,...

Thus, if the same service gets started 5 times iteratively, it will have 5 different invocation IDs assigned. And if you want to pinpoint a specific invocation of a service, it's the invocation ID you can use to uniquely identify it. (Besides the use as metadata when logging the invocation ID is also passed via the env var $INVOCATION_ID to the services btw; and systemctl status also shows it these days.)

One could say that what the Linux boot ID does for the system…

Like today at 8:04 | Open on mastodon.social

2 comments

Lennart Poettering

…(which is: identifying a specific reboot cycle universally and uniquely), the invocation ID does for an individual unit (which is: identifying a specific start cycle universally and uniquely).

Because of the conceptual similarity between boot IDs and unit invocation IDs, in v257 we decided to expose them in a similar way as boot IDs in journalctl.

Or in other words: for boot IDs you can use journalctl --list-boots/--boot=/-b to enumerate or filter, or focus on most recent boot.

today at 8:08 | Open on mastodon.social

Lennart Poettering

And for invocation IDs you can now use journalctl --list-invocations/--invocation=/-I to enumerate or filter, or focus on most recent invocations. (You might combine this with --unit=/-u depending on context.)

Simple example: "journalctl -u systemd-hostnamed -I".

And that's all for today. Enjoy!

today at 8:10 | Open on mastodon.social