When running scripts as root, you often need to execute commands with the environment of a different user. The most reliable way to retrieve another user’s PATH is by spawning a login shell under that user’s context. Basic Approach user1path=$(su – user1 -c ‘echo $PATH’) This spawns a login shell (-) as user1 and outputs…
Python provides several ways to check if files or directories exist, with different trade-offs depending on your use case. Using pathlib (recommended) The modern approach uses pathlib.Path, which is cleaner and more object-oriented: from pathlib import Path path = Path(‘/etc/passwd’) # Check if path exists (file or directory) if path.exists(): print(“Path exists”) # Check if…
Extracting a file extension from a filename is a common task. Here are the main approaches, with modern best practices. Simple Method with lastIndexOf() The most straightforward approach uses lastIndexOf() to find the last dot: function getExtension(filename) { const lastDotIndex = filename.lastIndexOf(‘.’); return (lastDotIndex < 1) ? ” : filename.substring(lastDotIndex + 1); } console.log(getExtension(‘file.txt’)); //…
When you initialize a new repository locally and try to push to GitHub or Bitbucket for the first time, you’ll likely encounter errors like: No refs in common and none specified; doing nothing. Perhaps you should specify a branch such as ‘master’. fatal: The remote end hung up unexpectedly This happens because your local repository…
The scp command handles multiple files efficiently, whether you’re pushing to a remote server or pulling from one. Here are the practical approaches for copying multiple files from remote to local. Brace Expansion Use brace expansion to specify discrete files: scp user@remote:file{1,2,3} ./ This works well when you have a known set of files with…
If you need to jump to a particular byte position in a file, Vim provides the goto command. This is useful when debugging binary files, working with hex editors, or when error messages reference byte offsets. Using the goto command In normal mode, press go followed by the byte number: 20go This moves the cursor…
When writing system administration scripts, you often need to check if a user account exists before taking action. There are several reliable methods to accomplish this. Using id command The id command retrieves user information and returns a non-zero exit code if the user doesn’t exist. This makes it ideal for conditional testing: user=”hello” if…
When you source a script using . script.sh or source script.sh, the $0 variable doesn’t point to the sourced script—it stays as the path of the parent shell or calling script. This creates a problem if you need the sourced script to know its own location. The solution: use ${BASH_SOURCE[0]} The ${BASH_SOURCE[0]} variable holds the…
The tilde expansion ~username works fine when the username is literal, but fails when the username is stored in a variable like ~$user. Bash doesn’t perform tilde expansion on variables by default—it only expands ~ at the beginning of a word before variable expansion happens. Using eval The most common approach is to use eval:…
MATE’s mouse settings don’t include a graphical toggle for natural (or inverted) scrolling on touchpads, unlike GNOME or Cinnamon. You’ll need to configure it through the command line or configuration files. Using synclient If your system uses Synaptics touchpad driver, you can invert scrolling direction with synclient: synclient VertScrollDelta=-111 synclient HorizScrollDelta=-111 Verify the change took…
MATE Desktop provides a traditional GNOME 2-style interface that many users prefer over modern GNOME Shell. Here’s how to install it on Linux Mint 17 Qiana. Install MATE Desktop sudo apt-get update sudo apt-get install mate-desktop-environment For the full MATE experience with extras: sudo apt-get install mate-desktop-environment-extras This adds additional applets, themes, and utilities not…
When renewing an SSL certificate, your CA will request a Certificate Signing Request (CSR). If you have the private key but need to generate a fresh CSR, OpenSSL handles this straightforwardly. Basic CSR Generation Generate a CSR from your existing private key: openssl req -new -key ssl.key -out req.pem This creates req.pem containing your CSR,…
When you need to restrict a find-and-replace operation to a specific block of text, Vim gives you several approaches. Using the %V atom The most straightforward method is the %V atom, which restricts pattern matching to the current visual selection: :%s/%Vfrom/to/gc This works regardless of the visual mode you used (character, line, or block). The…
When you try to unmount a filesystem, Linux sometimes refuses with a “device is busy” error. This safety mechanism prevents data loss when processes are actively using the filesystem. But there are legitimate cases where you need to force an unmount: a dead NFS server, a failed USB device, or a hung mount that won’t…
Vim’s filetype detection usually works automatically, but sometimes you need to manually override or set the filetype for a specific buffer. This guide covers manual filetype setting, debugging detection issues, and creating custom filetype definitions. Set Filetype Manually :set filetype=python Or use the shorthand: :set ft=python This immediately applies the syntax highlighting, indentation rules, and…
When Linux fails to boot with the error message “sulogin: can not open password database” despite /etc/passwd and /etc/shadow appearing intact, SELinux is often the culprit. The files exist and have correct content, but SELinux context labels are missing or corrupted, preventing the login process from reading them. Diagnose the Problem Boot into the initramfs…
To identify the developers who’ve contributed the most commits to a repository, use git log with some text processing: git log –format=’%aN’ | sort | uniq -c | sort -rn This returns a sorted list with commit counts and author names: 247 Paul Phillips 45 Dale Wijnand 12 Yamashita Yuu 10 Gilles Cornu 8 Josh…
Webpages often render differently when printed than on screen. Firefox’s developer tools make it straightforward to preview and debug print stylesheets without wasting paper. Using the CSS Media Type Emulator The fastest way to test print styles in Firefox: Open DevTools with F12 Click the Inspector tab (usually open by default) Look for the “Emulate…
Getting the full or abbreviated commit hash is essential for scripting, CI/CD pipelines, and version tracking. Here are the standard approaches. Full commit SHA-1 To retrieve the complete commit hash of the current HEAD: git rev-parse HEAD This outputs the full 40-character SHA-1 hash. It works in any Git repository state and is reliable for…
Backing up text messages from Android works best through Google Messages for real-time web access, or via ADB and third-party tools for local archives. Your approach depends on whether you need cloud sync, local storage, or both. Google Messages for Web (Easiest) The simplest method for most users is Google Messages, which syncs SMS and…