journalctl -fu servicename
If I am concerned about a specific service, and can trigger the problematic behavior.
In my head it stands for "fuck you" ☺️
this post was submitted on 21 Nov 2024
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tbh my go to command is just.. journalctl -fe -u service
ex :
journalctl -fe -u jellyfin
journalctl -fe -u nordvpnd
so I'd also like to know the answer to this question. my other go to is dumping journalctl to text files and parsing with grep and awk and creating my own reports with that parsed information.
grep -E is my favorite, I love regex capturing groups.
Apparently, less also has a feature built-in to filter out lines based on keywords:
https://raymii.org/s/snippets/Exclude_lines_in_less_or_journalctl.html#%3A%7E%3Atext=Once+your%2Cterm (skip the first paragraph, past those three links)
That's great to know!
Centralized logging like Graylog or Grafana Loki can help with a lot of this.
I tried to setup Loki but the documentation was atrocious. Everything was outdated, referring to tools that were marked deprecated but documentation for the replacements just didn't exist.
It might be a bit overkill but I use Grafana to do this (with Loki). It's a pretty involved setup as well, but you can filter and search by content, or date/time. It's doable on a desktop but mainly servers use it
I sometimes pipe journalctl into lnav, but it never works quite as well as i really want...
lnav is pretty cool and does mostly what you are describing.
uuhhh maybe here? https://lnav.org/
lnav is my go to regarding logs exploration, can't work without it.
If you are on gnome,.gnome logs do most of the things you want (if I recall correctly, some years since I run gnome)
I don't know of any graphical tools that let you do this, but generally, if you want to search for specific terms/times/commands or anything of that sort, piping journalctl into grep (and optionally grep into less) is pretty effective at finding stuff.
I wish there was something nice like that too.
In the server world that would usually involve doing something like sending the journal data to Elasticsearch using an Elasticsearch integration. But that involves setting up an Elasticsearch server and Kibana and so on which is very unwieldy for a desktop computer. It does work pretty well though in terms of filtering. But it also stores the data internally in indexes to speed up search.
Of course journald has a seemingly simple C API but writing code is a lot of work. There are probably API bindings for various languages.
systemctl status <service>
That is good but only shows the last 10-15 lines of the log, unless there is an arg to expand that, or a command to follow the log. I am aware of neither.
I usually use your suggested command to check if a service is up, then if it isn't, use journalctl to find out why.
Sounds like you want a siem like Wazuh. Its agent can collect journald logs from any number of systems. It also has a gui you can interact with to parse logs.
Well, just a monitoring stack, like for example Grafana, would probably be more suitable for this specific task (if we're doing central hosting/collection).
Kind of my main recommendation is to use something with OpenTelemetry. It's pretty much the standard protocol for transferring logs, traces and metrics, so if you set everything up with that, then you can swap out the visualization software with less pain.
Here's a guide for Grafana + OpenTelemetry Collector: https://grafana.com/docs/loki/latest/send-data/otel/
I'm seconding this recommendation