Troubleshooting Common Linux Problems: A Practical Guide

Table of Contents

• Start with the Basics: What’s Really Going On?

• System Logs: Your First Detective Tool

• Resource Hogs: CPU, Memory, and Disk Issues

• Permission Headaches and Dependency Drama

• Network Not Working? Step-by-Step Fixes

• Boot Issues and Frozen Systems

• Real-World Scenarios and Quick Solutions

• Wrapping Up

Start with the Basics: What’s Really Going On?

Before you dive into commands, take a breath and gather the facts.

• What’s broken? Is there an error message?

• Did something change recently (updates, new installs)?

• Can you reproduce the problem, or is it random?

Asking the right questions and getting a clear description of the issue saves you hours of wild goose chases

System Logs: Your First Detective Tool

Logs are your best friends when Linux acts up.

• General system logs:
  tail -n 50 /var/log/syslog or tail -n 50 /var/log/messages

• Kernel messages:
  sudo dmesg | tail -20

• Authentication issues:
  tail -n 50 /var/log/auth.log or /var/log/secure

• Boot problems:
  cat /var/log/boot.log or use head/tail for quick peeks**

• Pro tip: Use grep "error" to search for red flags fast

Resource Hogs: CPU, Memory, and Disk Issues

Is your system sluggish or unresponsive?

• Check system load:

uptime shows load averages

• See what’s eating resources:

top, htop, or ps aux --sort=-%cpu | head for CPU hogs
ps aux --sort=-%mem | head for memory guzzlers

• Disk space:

df -h for usage, du -sh * to find big files, and
sudo apt clean or sudo dnf clean all to clear package caches.

• If a process is out of control, use kill -9 PID (replace PID with the process ID).

Permission Headaches and Dependency Drama

Permission denied?

• Check with ls -la filename

• Fix with chmod +x filename or change ownership with chown
  user:group filename.

Missing libraries or dependencies?

• For errors like “libsomething.so.2: cannot open shared object file,” use:

apt-file search libsomething.so.2 (Debian/Ubuntu)
dnf provides */libsomething.so.2 (Fedora/RHEL)

• Install the required package with your package manager

Network Not Working? Step-by-Step Fixes

• Check your network interface:
  ip link

• Verify your IP address:
  ip addr

• Can you reach your gateway?
  ip route show and ping -c 4

• Test DNS:
  ping -c 4 google.com

• Check open ports:
  nc -zv google.com 443.

• If SSH locks you out, try accessing the server locally or through the console, and check for high load or network failures

Boot Issues and Frozen Systems

• Boot failures:
  Check /var/log/boot.log for clues.
  Use dmesg for kernel and hardware errors.

• Frozen system?
  Try switching TTYs with Ctrl+Alt+F2, or use the hypervisor console if it’s a VM.

• Safe reboot:
  If all else fails, use echo b > /proc/sysrq-trigger for a safe reboot

Real-World Scenarios and Quick Solutions

Script works manually but fails in cron?

• Add logging to your script.

• Compare environment variables between manual and cron runs.

• Fix missing PATH or variables in your script.

• Intermittent network drops?

• Check logs for hardware errors.

• Monitor with ping or dmesg -w for real-time clues

Wrapping Up

Linux troubleshooting is all about staying calm, asking the right questions, and using the right tools.

• Always check logs first.

• Monitor your resources.

• Don’t ignore permissions or dependencies.

• Automate what you can, but know how to dig in manually.

• And remember, the Linux community is massive-don’t be afraid to
  search forums and share your own solutions. Happy troubleshooting!