`journalctl` command

Read systemd logs for services and the system.

Processes & services
Package systemd
9 options · 8 examples

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Syntax
Common options
Examples
Guides
Related commands

Syntax

journalctl [options]

Provided by the systemd package. Run man journalctl for the full manual.

Common options

Option	What it does
`-u UNIT`	Logs of one service
`-f`	Follow new entries
`-n N`	Last N lines
`-b`	Since the last boot (-b -1 = previous boot)
`--since / --until`	Time range, e.g. "1 hour ago"
`-p LEVEL`	Priority, e.g. err
`-k`	Kernel messages
`--disk-usage`	Space used by the journal
`--vacuum-size=SIZE`	Shrink the journal

Examples

Logs of a service
```
journalctl -u nginx
```
Follow a service live
```
journalctl -u nginx -f
```
Last 100 lines
```
journalctl -u ssh -n 100
```
Since the last boot
```
journalctl -b
```
Errors only
```
journalctl -p err -b
```
Last hour
```
journalctl --since "1 hour ago"
```
Kernel messages
```
journalctl -k
```
Shrink the journal to 500 MB
```
sudo journalctl --vacuum-size=500M
```

journalctl guides

How to Automate Journalctl Log Cleanup on Linux Linux · Updated Apr 2025

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