How to manage linux operating systems?

Here are the 50 practical scenarios related on how to manage running linux operating systems, booting systems, process management, tuning and scheduling, interrupt logs, securely transferring files, and starting/stopping services. These scenarios are important for the RHSA (Red Hat Certified System Administrator) exam:

Operating Running Systems:

1. Change the current runlevel to a specific target (e.g., multi-user.target).
2. List available targets and identify the current target.
3. Enable a service to start on boot.
4. Disable a service from starting on boot.
5. Check the status of a specific service.
6. Reload a service’s configuration without stopping it.
7. Use “systemctl” to identify failed units.
8. Use “journalctl” to view system log messages.
9. View a specific log level in the systemd journal.

Booting Systems:

1. Boot the system into rescue mode.
2. Interrupt the boot process and access the GRUB menu.
3. Set a different target as the default boot target.
4. Identify the default target in the GRUB configuration.
5. Configure GRUB to boot a specific kernel version.

Process Management:

1. Display a list of all running processes.
2. Find and terminate a specific process by name.
3. Use “ps” to show a process tree.
4. Change a running process’s priority using “nice.”
5. Send a signal to a process to stop it gracefully.
6. Determine which process is listening on a specific port.
7. Identify the parent process of a given process.

Tuning and Scheduling:

1. Set up a cron job to run a script every day at a specific time.
2. List all scheduled cron jobs for the current user.
3. Configure “ulimit” to limit resource usage for a user.
4. Adjust the kernel I/O scheduler to optimize performance.
5. Use “sysctl” to change kernel parameters.
6. Display CPU and memory usage using “top.”
7. Monitor disk space usage in real-time with “iostat.”
8. Monitor network activity using “iftop” or “nload.”
9. Schedule a one-time task using “at.”
10. Create a recurring task using “cron” and schedule it to run hourly.
11. View and edit “cron” jobs for a specific user using “crontab.”

Interrupt Logs:

1. View the contents of the system log using “dmesg.”
2. Search for kernel error messages in “dmesg.”
3. Check for hardware-related messages in “dmesg.”
4. Use “journalctl” to view systemd logs with specific priorities.
5. Monitor logs in real-time with “tail” or “journalctl -f.”
6. Check the log rotation settings and policies.
7. Create a custom log file for a specific application.

Securely Transferring Files:

1. Use “scp” to securely copy a file from one server to another.
2. Transfer files securely between systems using “rsync.”
3. Create and use SSH keys for passwordless file transfers.
4. Use “sftp” to interactively transfer files over SSH.

Starting and Stopping Services:

1. Start a service using “systemctl start.”
2. Stop a service using “systemctl stop.”
3. Restart a service using “systemctl restart.”
4. Enable a service to start on boot using “systemctl enable.”
5. Disable a service from starting on boot using “systemctl disable.”
6. Check the status of a service using “systemctl status.”
7. Reload a service’s configuration using “systemctl reload.”

Note :

These practical scenarios cover various aspects of operating Linux systems, managing processes, configuring system booting, tuning system performance, monitoring logs, and securely transferring files – all of which are important skills for RHSA certification and real-world system administration tasks.