Debugging in Linux is essential for troubleshooting system issues, application bugs, or network problems. Here’s a simple guide to get you started with common Linux debugging tools and techniques.

1. Checking System Logs

Linux logs are a great starting point for debugging. Logs capture events related to the kernel, applications, and services.

View Logs with journalctl

# List all processes

ps aux



# View processes in real-time

top

Find a Process by Name with pgrep

pgrep <process_name>

Debug a Process with strace

strace traces system calls made by a process.

strace -p <pid>`

Debug a Process with gdb

gdb is used for debugging compiled applications.

gdb <program_name> <pid>

1. Networking Debugging
   Check Active Connections with netstat or ss

Using netstat

netstat -tuln

Using ss

ss -tuln

Test Connectivity with ping or curl

ping <hostname_or_ip>

curl -v http://

Check Firewall Rules with iptables or ufw

Using iptables

sudo iptables -L -v

Using ufw

sudo ufw status verbose

1. Disk and Filesystem Debugging
   Check Disk Usage with df and du

Disk space usage

df -h

Directory size usage

du -sh <directory_name>

Check Disk Health with fsck and smartctl

Check and repair filesystem (run in unmounted mode)

sudo fsck /dev/sdX

Check disk health using smartctl

sudo smartctl -a /dev/sdX

1. Memory Debugging
   Check Memory Usage with free and vmstat

Memory usage

free -h

System performance and memory statistics

vmstat 1 5

Analyze Memory Leaks with valgrind

valgrind --leak-check=yes ./your_program

1. Kernel Debugging
   Check Kernel Messages with dmesg
   

dmesg | tail

Debug Kernel Panics with kdump

Ensure kdump is installed and configured for capturing kernel crash dumps.

sudo systemctl start kdump

Conclusion

Effective debugging in Linux requires a good understanding of system logs, processes, network, disk, and memory. Start with logs, monitor processes, trace system calls, and analyze system resources. Mastering these tools will help you quickly diagnose and resolve issues.