Local branches List all branches on your local repository: git branch This shows only branches that exist locally on your machine. Remote branches To list all branches on the remote server, use the -r flag: git branch -r This displays remote-tracking branches — local references to branches that exist on the remote repository. These are…
Modern Fedora systems keep multiple kernel versions available, but older kernels are tucked in a submenu rather than appearing as top-level GRUB2 entries. This requires a slightly different approach when setting them as your default boot option. Understanding the GRUB2 submenu structure When you run: grep menuentry /boot/grub2/grub.cfg | cut -d “‘” -f2 You’ll see…
Use usermod to add a user to supplementary groups. The -a (append) flag is critical — without it, you’ll remove the user from all groups not explicitly listed. usermod -a -G group_name user_name To add a user to multiple groups at once: usermod -a -G group1,group2,group3 user_name Options explained -a, –append Append the user to…
If you’re still seeing Chrome warnings about Flash Player being out of date on Linux, understand that Adobe discontinued Flash Player entirely in December 2020. Chrome removed all Flash support in version 88 (early 2021) and has no mechanism to run Flash content anymore. If you’re encountering this message in 2026, you’re likely: Using an…
If you’ve merged a branch and want to undo it, Git provides several approaches depending on your situation. The key difference is whether you have uncommitted local changes and whether the merge has already been pushed. Using git reset for unpushed merges If the merge is only in your local repository and hasn’t been pushed,…
Working in an SVN repository often leaves behind temporary build artifacts, compiled outputs, and editor cache files. Unlike Git’s git clean command, SVN has no built-in cleanup mechanism for untracked files. Using svn st to Identify Untracked Files The svn status command (or svn st) marks untracked files with a ? prefix. You can leverage…
If you’ve made changes to your working copy but haven’t committed them yet, you can discard them using svn revert. This is useful when you want to abandon edits and go back to the last committed version. Basic Revert To revert all changes in your working copy, run this from the repository root: svn revert…
A hard link is an additional directory entry pointing to the same inode as the original file. Unlike symbolic links, hard links share the same inode number and have identical permissions, ownership, and content. To find all hard links to a file, you need to locate every directory entry with the same inode. Using find…
In computer systems, resources must be balanced across available hardware to maximize performance. The Linux kernel runs migration threads as per-CPU daemons to handle this work. These threads manage task migration between CPUs, CPU hotplug operations, and stop-machine synchronization. You can observe migration threads on any modern system: $ ps aux | grep migration root…
When you try to unmount a filesystem with umount, Linux may report “device is busy.” This is a safety mechanism — the kernel blocks unmounting when processes or kernel threads are actively accessing the partition or holding open files on it. Forcing an unmount without understanding what’s using the filesystem risks data corruption and data…
When you dock a laptop with an external USB keyboard, the built-in keyboard becomes a nuisance—it’s too easy to brush keys while typing and trigger unwanted input. Rather than disabling the keyboard at the BIOS level or physically disconnecting it, you can use the xinput tool to disable and re-enable it from within your Linux…
When verifying file integrity on Linux, you’ll typically reach for one of several checksum utilities. A natural question: which one is fastest? The answer depends heavily on whether I/O or CPU is your bottleneck. Disk I/O Dominates on Most Systems In realistic scenarios with typical storage, disk I/O is almost always the limiting factor. Test…
iPhone videos often play rotated 90 degrees when opened in non-Apple software on Linux because the rotation data is stored as metadata rather than baked into the video stream itself. FFmpeg handles this reliably by re-encoding with the transpose filter, which physically rotates the frame data. Understanding the Transpose Filter FFmpeg’s transpose filter supports four…
Hadoop 2.x reached end-of-life in 2016. This guide covers setup for learning purposes and legacy system maintenance only. For production deployments, use Hadoop 3.x or later, which includes performance improvements, better YARN scheduling, HDFS erasure coding, and improved security. Cloud-managed options like AWS EMR, Google Dataproc, and Azure HDInsight eliminate most operational overhead. This guide…
LVM abstracts physical storage into logical volumes, letting you resize filesystems online, add drives transparently, and manage capacity without downtime. This guide covers the most common task: extending a mounted ext4 filesystem when you need more space. Prerequisites Online extension requires the resize_inode option enabled on your ext4 filesystem. Check this first: tune2fs -l /dev/vg/lv_home…
Linux device names like /dev/sda and /dev/sdb are unreliable identifiers for physical hardware. They shift when you add, remove, or reseat drives, and there’s no guaranteed mapping between a SATA port and its device name. When a disk fails, you need to know exactly which physical slot to replace—guessing wrong takes down the wrong system….
Symbolic links (symlinks) are aliases that point to other files or directories. Most operations treat them transparently—programs reading or writing through a symlink behave as if working with the target directly. Understanding how to create, test, and manage them correctly is essential for system administration. Creating Symbolic Links Create a basic symlink: ln -s ../target…
When managing multiple servers, you need reliable ways to verify which hosts are reachable. While orchestration tools like Kubernetes and Ansible handle monitoring at scale, a lightweight Bash script works well for quick spot checks, operational tasks, or smaller deployments. Basic ICMP Reachability Check The simplest approach uses ping to test ICMP reachability: ping -W…
Modern Linux systems use GRUB2 as the bootloader. You’ll set the default boot entry either through the configuration file or via command-line tools. View Available Boot Entries First, list all available GRUB2 menu entries: grep ^menuentry /etc/grub2.cfg | cut -d “‘” -f2 On UEFI systems, use /etc/grub2-efi.cfg instead. If you’re unsure which mode your system…
Xen remains a production-grade hypervisor used in enterprise environments (AWS EC2, Citrix Hypervisor), though KVM has become the default for most Linux distributions. This guide covers building a stable Xen Dom0 on current Fedora releases using modern kernel sources. Hardware Considerations This guide assumes server-class hardware with: Intel or AMD processor with virtualization extensions (VT-x…