Last Sync: 2022-08-21 09:00:05

Linux/journald.md

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+---
+categories:
+  - Linux 
+tags: [journal, systemd, sytems-programming]
+---
+
+
+# `journald`
+
+`journald` is a program that comes as default with [systemd](/Linux/systemd.md). It is a service fror collecting and storing system-level log data. I keeps a track of all [kernel](/Operating_Systems/The_Kernel.md) processes. It is invaluable when tracing the source of problems and errors that may arise on the system level. It keeps a track of all kernal processes.
+
+![](/img/journald.png)
+
+
+## `journalctl` 
+
+We use `journalctl` to access the logs. The command by itself outputs the entire log which will be huge and hard to scroll through. We can refine the results with modifiers.
+
+
+### View logs for a specific process with pid
+
+```bash
+journalctl _PID=1234
+```
+
+### View logs for a specific time period
+This can be really helpful since you can bracket the most recent events which will be more memorable.
+
+```bash
+journalctl -S -1h
+```
+
+### View logs for a specfic systemd unit
+```bash
+journalctl -u cronie.service
+```
+
+### View boot logs 
+```bash
+journalctl -b
+```
+
+#### Identify specific boot 
+
+```bash
+journalctl --list-boots
+
+```