The cat (concatenate) command is one of the most frequently used utilities in Unix/Linux systems. While it’s often seen simply showing file contents, it can do much more—including creating, combining, inspecting, and transforming text streams efficiently. Below are 10 practical,…
You’ve dipped your toes into tcpdump, maybe caught a few web packets or seen your router chatting away. That’s a great start! But what if you need to go deeper? What if you’re chasing a phantom network issue, analyzing application…
When network issues strike, tcpdump is often the first tool professionals reach for. It’s like a microscope for your network — allowing you to see every packet traveling in and out of your system. But without filters, tcpdump captures everything,…
The hardware vendor info or serial number can be very helpful to open a support case for Linux admins. We will cover this topic today to get this info from Linux system. We will use dmidecode command to get this…
“No space left on device” (ENOSPC) usually means exactly what it says—the disk is full. But every so often you hit this error while df still shows plenty of free space, which is understandably confusing. This guide walks through the troubleshooting process…
Rsync is a unique, full-featured file transfer facility. It can perform differential uploads and downloads (synchronization) of files across the network, transferring only data that has changed. For example, if there is a local copy of a 50MB file and…
Sometimes when we ssh to Linux box, we get this error “WARNING: Your password has expired.” You must change your password now and login again! Changing password for user ocp. Changing password for ocp.” What does “WARNING: Your password has…
Rp_filter is short for reverse path filtering on Linux. We can use this to filter packets on Linux. Here are 5 common questions about rp_filter. What is reverse path filtering? Reverse path filtering is a mechanism adopted by the Linux…
NFS performance is important for the production environment. In this tutorial, we will review how to use DD command to test local storage and NFS storage performance. Test nfs storage performance on Linux There are some differences between each testing…
A system is having a single core, and if there is a single process consuming all the CPU Time, then CPU utilization will show 100% utilization. But in case of multi core systems it is not necessary that all the…
