When you export a variable in Bash, it becomes available to all child processes spawned from your shell. Sometimes you need to remove that exported status or delete the variable entirely. There are two main approaches depending on what you want to achieve. Remove export status but keep the variable If you want the variable…
[md] Systemd’s coredump handler captures process crash dumps by default, which can consume significant disk space on development or test systems. Here’s how to disable or control coredump storage. ## Quick Solution Edit /etc/systemd/coredump.conf and set: [Coredump] Storage=none Then reload the systemd daemon: systemctl daemon-reload This prevents coredumps from being stored permanently while still logging…
When writing C programs on Linux that handle file paths, you need to allocate buffers safely. The kernel defines maximum path and filename lengths through standard macros in <linux/limits.h>. Getting the limits On Linux systems, <linux/limits.h> provides two key macros: NAME_MAX — maximum length of a single filename component (255 characters) PATH_MAX — maximum length…
When you have an absolute path like /foo/bar/baz.txt and need to split it into its components, Bash provides two essential utilities: dirname and basename. Using dirname and basename The dirname command returns the directory portion of a path, while basename returns just the filename: p=”/foo/bar/baz.txt” dirname “$p” # Output: /foo/bar basename “$p” # Output: baz.txt…
When you have a password-protected RSA private key (indicated by the Proc-Type: 4,ENCRYPTED header), you’ll need to decrypt it before using it with most applications. The openssl command handles this straightforwardly. Basic decryption Use openssl rsa to decrypt the key: openssl rsa -in encrypted_key.pem -out decrypted_key.pem You’ll be prompted to enter the password for the…
By default, Git doesn’t automatically configure your local branch to track its remote counterpart. You need to explicitly set up this tracking relationship so that git pull and git push know which remote branch to synchronize with. Setting Up Tracking for an Existing Branch If you already have a local branch and want it to…
Chrome on iOS has a fundamental limitation: it cannot accept self-signed SSL certificates or custom Certificate Authorities (CAs) because iOS restricts all browsers to use the system’s certificate validation. Unlike desktop Chrome, you cannot bypass this through browser settings. Why This Limitation Exists iOS enforces strict security policies where all apps—including Chrome, Safari, and Firefox—must…
Chrome on Linux sometimes fails to start with the error “Your profile could not be opened correctly.” This typically happens when the browser’s profile database becomes corrupted, often after a crash or unclean shutdown. Quick Fix: Remove Corrupted Web Data The most reliable solution is to delete the corrupted Web Data file from your Chrome…
Cinnamon on Fedora offers solid theming options through the official repositories. Here’s a practical approach to building a cohesive desktop environment with matching window borders, icons, controls, and cursor themes. Installing Theme Packages Start by installing available theme packages from the Fedora and Cinnamon repositories: sudo dnf install cinnamon-themes cinnamon-control-center sudo dnf install papirus-icon-theme adwaita-icon-theme…
When you try to redirect output from a sudo command to a file using >, you’ll hit a permission error: $ sudo echo “echo hello” > /usr/local/bin/hello bash: /usr/local/bin/hello: Permission denied This happens because the shell processes the redirection operator > before sudo runs. The redirection happens in your unprivileged shell context, not as root….
When you’re managing a Linux server remotely over SSH, determining whether a USB drive has been connected requires checking kernel messages and device listings since you can’t visually inspect the hardware. Check dmesg for USB Detection Events The most reliable method is examining kernel logs with dmesg. When a USB device is detected, the kernel…
On a Linux system, you often need to let regular users mount and unmount specific devices without requiring sudo or the root password. This is common for external drives, USB devices, or secondary internal disks. There are several approaches, each with different security and usability tradeoffs. Using /etc/fstab with the user Option The simplest approach…
Converting text to lowercase is a common task in shell scripts and command-line workflows. Linux offers multiple approaches, each with different trade-offs in performance, portability, and Unicode handling. Using tr for simple conversions The tr command translates characters and is widely portable across Unix-like systems: echo “HELLO WORLD” | tr ‘[:upper:]’ ‘[:lower:]’ Output: hello world…
GNU Screen is a terminal multiplexer that lets you manage multiple shell sessions within a single window. If you’re new to it, here are the best resources to get up to speed, plus practical tips for getting started. Getting Started with Screen For an introduction to the basics, start with A quick tutorial on screen….
Connecting your application to a MySQL database is fundamental to most backend systems. Rather than shelling out to the mysql command-line client, you’ll use language-specific connectors that provide proper connection pooling, error handling, and prepared statements. Language-Specific MySQL Drivers The best approach depends on your tech stack: Python Use mysql-connector-python for straightforward connections or PyMySQL…
Merging PDFs on Linux is straightforward with several tools available, each suited to different needs. Whether you need a quick command-line merge or want to reorder pages visually, here’s what works best. pdfunite: The Simplest Approach The fastest way to merge PDFs is with pdfunite from poppler-utils: pdfunite file1.pdf file2.pdf file3.pdf output.pdf Install it if…
When a filesystem listed in /etc/fstab fails to mount during boot, the system can hang or drop to an emergency shell, preventing normal startup. This happens because the kernel treats all mount entries equally by default. Non-critical filesystems—network shares, external drives, or optional data partitions—shouldn’t block your entire system from booting. Understanding fstab mount options…
Managing a cluster of servers, you’ll want to be notified when they come back online after restarts or unexpected reboots. Email notifications on boot let you track infrastructure changes and catch potential issues early. Using crontab @reboot The simplest approach is a crontab @reboot entry that runs once at startup. This executes before most services…
The core problem here is legitimate: if you’re running multiple jobs on the same dataset where the mapper phase produces identical intermediate results, recomputing those results is wasteful. However, skipping the mapper phase entirely breaks MapReduce’s processing model. There are better approaches. Why You Can’t Just Skip the Mapper MapReduce assumes data flows through map…
When a kernel panic occurs on a remote Linux server, manual intervention via SSH becomes impossible. The kernel can be configured to automatically reboot after a panic, allowing the system to recover without human intervention. Enable Kernel Panic Auto-Reboot The kernel.panic parameter controls this behavior. A value of 0 disables auto-reboot; any positive integer specifies…