Linux Tips: 10 Things You Shouldn’t Do (And What to Do Instead)

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Avoid common pitfalls in Linux administration by following these practical tips. Learn how to handle permissions, troubleshoot errors, and secure your system effectively.

1. Avoid Running Commands That Change Multiple Properties

Instead of running commands that change a large number of properties, focus on specific files or directories related to the issue you are troubleshooting.

Example:

Avoid using:

chmod 777 everything

This can cause security issues and break applications such as SSH or sudo. Instead, identify why you need to run these commands and explore more secure alternatives.

2. Don’t Use Root as a Daily Driver

Unlike the Administrator account in Windows, the Linux root user bypasses security warnings and checks. Using sudo to run privileged commands is safer and provides an audit trail for tracking purposes.

3. Understand the rm Command Flags

The -r (recursive) and -f (force) flags in the rm command are permanent. Using them can delete files or directories without confirmation.

Example:

rm -rf /folder

This command will permanently delete the specified folder and all its contents without asking, “Are you sure?”

4. Troubleshooting Permission Denials

When troubleshooting access issues, consider both DAC (Discretionary Access Control) and MAC (Mandatory Access Control).

  • DAC: File permissions (e.g., chmod, chown).
  • MAC: Tools like SELinux or AppArmor enforce additional security layers.

Example:

Check SELinux logs:

cat /var/log/audit/audit.log

5. Networking: Check Software Firewalls

Don’t assume networking issues are related to hardware alone. Software firewalls like iptables or SELinux might be blocking connections.

Example:

Use iptables commands to inspect rules:

iptables -L -v -n

If no rules are specified, SELinux might be configured at the IP layer.

6. Use SSH Key-Based Authentication

Avoid using password authentication in SSH. Passwords are prone to brute-force attacks, especially dictionary-based ones.

Exception:

Users who are part of a directory service might require passwords.

7. Always Identify the Time Zone

When checking timestamps, don’t assume the server time is local or UTC. Use the below command to confirm the timezone.

Example:

date
cat /etc/timezone
timedatectl

8. Troubleshoot Kernel Errors Effectively

When troubleshooting kernel errors, search the error message online along with the kernel and software version.

Example:

Use Bing or Google to search for:

<error message> <kernel version>

9. Handle Read-Only Filesystems

If you cannot modify a file even as root, check if the filesystem is mounted as read-only.

Steps:

  1. Run:dmesg Look for errors indicating filesystem integrity issues.
  2. Check file attributes using:lsattr Files with the +i attribute are immutable and cannot be modified, even by root.

10. Don’t Guess When Unsure

If you’re unsure how to proceed, don’t guess! Reach out to Linux experts or consult the documentation. Guessing can worsen the issue and make recovery more difficult.

Conclusion

By avoiding these common pitfalls, you can improve your Linux administration skills and ensure a more secure and efficient environment. Always prioritize understanding the commands you use and consult experts when necessary.

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