Configure user resource limits

Hosaac is a RHEL Sysadmin at Google. He needs to prepare a lecture to teach a class of interns about resource limits in Red Hat Enterprise Linux. The lecture must include the following:

1. The history of resourse limits in GNU/Linux.
2. What commands are used to set and view resource limits.
3. Give several examples of commands setting and view various resource limits on a RHEL server.

Certainly! Here's the lecture that Hosaac can present to the class about resource limits in Red Hat Enterprise Linux:

"Hello, everyone! Today, we're going to delve into the topic of resource limits in Red Hat Enterprise Linux (RHEL). Resource limits allow us to manage and control the allocation of system resources to processes, ensuring fair distribution and preventing resource exhaustion. Let's begin by understanding the history of resource limits in GNU/Linux."

"The concept of resource limits in GNU/Linux traces back to the POSIX (Portable Operating System Interface) standard, which defines the behavior of operating systems and their interfaces. The POSIX standard introduced the 'ulimit' command, which stands for 'user limit,' to set and view resource limits for individual users or processes. This command became an integral part of the GNU/Linux ecosystem and is widely used today."

"Now, let's explore the commands used to set and view resource limits in RHEL. The primary command we'll be working with is 'ulimit,' which allows us to manage resource limits. Here are a few examples of how we can use 'ulimit' to set and view various resource limits on a RHEL server."

1. Set the maximum number of open file descriptors for the current shell session to 1024:
   • ulimit -n 1024
2. View the current maximum number of open file descriptors for the current shell session:
   • ulimit -n
3. Set the maximum CPU time (in seconds) for a process to 300:
   • ulimit -t 300
4. View the current maximum CPU time for a process:
   • ulimit -t
5. Set the maximum size (in kilobytes) of a core file that can be generated when a program crashes to 5000:
   • ulimit -c 5000
6. View the current maximum size of a core file:
   • ulimit -c

"These are just a few examples to give you a sense of how 'ulimit' can be used to manage resource limits on a RHEL server. The 'ulimit' command provides flexibility to control various aspects such as file descriptors, CPU time, core file size, memory usage, and more."

"It's important to note that resource limits set using 'ulimit' are specific to the current shell session. To set system-wide resource limits that apply to all processes, you can modify the '/etc/security/limits.conf' file."

"By understanding and effectively managing resource limits, you can optimize the utilization of system resources and ensure fair allocation across processes. It's crucial to consider resource limits when deploying applications, as it helps maintain system stability and prevents resource exhaustion."

"I hope this introduction to resource limits in RHEL has provided you with valuable insights. I encourage you to explore further, experiment with different resource limits, and refer to the official documentation for detailed information on managing resource limits in RHEL."

"Thank you for your attention, and I wish you success in your journey as RHEL sysadmins!"