Linux Survival Basics
Read-only, can be slowRead Mount and fstab Warnings
You need warning-level boot logs related to mounts, fstab, or dependencies.
Command
journalctl -b -p warning --no-pager | grep -iE 'mount|fstab|dependency'Before you run this
System impact: Read-only. Can create load on large logs, directories, filesystems, or process tables.
When not to use it: Do not paste full logs publicly without redacting hostnames and paths.
Expected output
Current-boot warning lines that mention mount, fstab, timeout, or dependency errors.
System impact
Read-only, can be slow. Nothing changes. The command reads current state and prints diagnostic evidence.
Scope this to the smallest useful path or service on busy systems.
Recovery / rollback: no state is changed.
When to use it
Use after a mount failure or slow boot.
When not to use it
Do not paste full logs publicly without redacting hostnames and paths.
Example run
Commands shown
These are the commands shown for inspection. Treat them as an example, not proof that your system will behave identically.
journalctl -b -p warning --no-pagerjournalctl -b -p warning --no-pager | grep -iE 'mount|fstab|dependency'
next steps
Related commands
Read Current-Boot Logs for One Service
Ignore stale logs and inspect only what happened since this boot.
journalctl -u nginx -b --no-pager -n 80
Find OOM Killer Lines in the Kernel Journal
Before restarting a service, prove whether the kernel killed it.
journalctl -k --since '24 hours ago' --no-pager | grep -iE 'out of memory|oom-killer|killed process'
Spot OOM Kills in the Kernel Journal
Exit code 137 often means the kernel has something to say.
journalctl -k --since "2 hours ago" --no-pager -o short-iso | grep -Ei 'out of memory|oom|killed process'
Find Errors Before Reading Every Log Line
The error was in the log. The problem was finding it without reading noise.
grep -iE 'error|failed|denied|timeout' /var/log/nginx/error.log | tail -40
Show Only Recent Errors
The log had old failures too. I only cared about the newest ones.
grep -iE 'error|failed|denied|timeout' /var/log/nginx/error.log | tail -10
next diagnostic step
Where to go from this command
- Mount failed from fstab hub Use to read boot-time mount failures.
Study mapping
Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.
Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.