Programming

Programming

Configure Windows Proxy Settings via Command Line
ByEric Ma Mar 24, 2018Apr 11, 2026

For any current Windows system, netsh winhttp is the standard command-line tool for proxy configuration. WinHTTP handles system-level proxy settings used by Windows Update, built-in applications, and services that don’t rely on browser-specific configuration. Set a proxy with bypass list netsh winhttp set proxy proxy-server=”proxy.example.com:8080″ bypass-list=”localhost;127.0.0.1;*.internal.local” Use semicolons to separate multiple proxy servers or bypass…

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Programming

Understanding the @ Symbol in Makefiles
ByEric Ma Mar 24, 2018Apr 11, 2026

The @ symbol in Makefiles suppresses the echo of the command itself before execution. When you run a target, make normally prints each command to stdout before running it. Adding @ before a command hides that echo, showing only the command’s output. Basic example Without @: all: echo “For correctness test of basic get and…

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Programming

Counting Files in a Directory: Common Pitfalls and Best Practices
ByWeiwei Jia Mar 24, 2018Apr 11, 2026

The most reliable one-liner to count files in the current directory is: find . -maxdepth 1 -type f | wc -l This counts only regular files (not directories or symlinks) and handles edge cases that trip up simpler approaches. Why Not Use ls | wc -l? The common ls | wc -l command has several…

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Programming

Upgrading Fedora with dnf system-upgrade: A Complete Guide
ByEric Ma Mar 24, 2018Apr 11, 2026

Fedora upgrades are straightforward with dnf system-upgrade, the standard tool for network-based distribution upgrades. This replaces the older fedup tool and handles everything from downloading packages to managing the upgrade environment. Pre-Upgrade Checklist Before starting any upgrade: Update your current system: sudo dnf upgrade Back up critical data — especially /etc, home directories, and application…

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Programming

Safely Disabling FirewallD on Fedora
ByEric Ma Mar 24, 2018Apr 11, 2026

Fedora uses FirewallD as its default firewall management service. If you’re running servers in a trusted internal cluster or isolated environment where network-level filtering isn’t needed, you can disable it entirely. Stop and Disable FirewallD To completely disable the firewall: sudo systemctl stop firewalld sudo systemctl disable firewalld The stop command halts the service immediately….

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Programming

Migrating from firewalld to iptables on CentOS 7 and Fedora
ByEric Ma Mar 24, 2018Apr 11, 2026

If you need direct control over your firewall rules, you can disable firewalld and use iptables instead. This guide covers the setup process and best practices for maintaining persistent rules. Stop and disable firewalld If firewalld is currently running, stop it and prevent it from starting on boot: sudo systemctl stop firewalld sudo systemctl disable…

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Programming

Extracting Directory and Filename from a Path in C
ByEric Ma Mar 24, 2018Apr 11, 2026

Parsing directory and filename components from an absolute path is a common task in systems programming. Linux provides dirname() and basename() functions for this purpose, but they have implementation-specific behaviors that can cause bugs if you’re not careful. Using dirname() and basename() The POSIX standard defines both functions, though the implementations vary. Here’s the safest…

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Linux

Printing Text Files from Linux Terminal with lp and CUPS
ByEric Ma Mar 24, 2018Apr 11, 2026

The lp command is the standard tool for printing from the Linux command line. It interfaces with CUPS (Common Unix Printing System), the printing backbone on virtually all modern Linux distributions. Basic Printing Send a file to your default printer: lp text-file.txt Specify a particular printer: lp -d printer-name text-file.txt List available printers and identify…

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Programming

Fix Ghostscript stackunderflow Error in PDF Conversion
ByEric Ma Mar 24, 2018Apr 11, 2026

When converting PostScript to PDF using ps2pdf with certain PDFSETTINGS options, you may hit this error: GPL Ghostscript 9.10: Set UseCIEColor for UseDeviceIndependentColor to work properly. Unrecoverable error: stackunderflow in .setdistillerparams This occurs when Ghostscript’s internal stack runs out of expected values during PDF distiller parameter processing. The root cause is usually conflicting color space…

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Programming

Print Text Files with Line Numbers: nl, cat, and More
ByEric Ma Mar 24, 2018Apr 11, 2026

The nl command is purpose-built for adding line numbers to text files: nl text-file By default, nl numbers all non-empty lines and skips blank lines. This behavior is controlled by the body section style, which defaults to t (text only). Common nl options Number all lines including blanks: nl -ba text-file Start numbering at a…

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Programming

Display Line Numbers Separately from Text in Emacs
ByEric Ma Mar 24, 2018Apr 11, 2026

Line number displays in Emacs can feel cramped without proper spacing. Modern Emacs provides built-in control over line number formatting and width—no external packages needed. Using display-line-numbers-mode display-line-numbers-mode is the standard in Emacs 25+ and should be your default choice. It’s faster and more maintainable than the older linum-mode. Enable it globally: (global-display-line-numbers-mode t) To…

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Programming

Exporting and Importing Thunderbird Message Filters
ByEric Ma Mar 24, 2018Apr 11, 2026

Thunderbird stores message filters in per-account configuration files, making it inconvenient to replicate filters across multiple accounts or installations. Rather than recreating filters manually, you can copy filter files directly or use symbolic links to keep filters synchronized. Where Thunderbird Stores Filters Thunderbird saves filter rules in msgFilterRules.dat, a plain text configuration file. Each account…

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Linux

Control Flow in Bash: Using Functions Instead of goto
ByEric Ma Mar 24, 2018Apr 11, 2026

Bash doesn’t have a goto statement, and that’s intentional. The language is designed to encourage cleaner control flow patterns that are easier to debug and maintain. When you feel the urge to jump around in your script, there’s almost always a better approach. Functions and Early Return The cleanest pattern is extracting logic into functions…

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Programming

Email Backup: Comparing offlineimap, mbsync, and doveadm
ByEric Ma Mar 24, 2018Apr 11, 2026

Backing up a complete IMAP account with thousands of messages across nested folders requires automation to preserve folder structure and avoid manual errors. This guide covers three modern tools and provides detailed setup for the most flexible option. Choosing your backup tool offlineimap — Most flexible for complex folder structures and label handling. Active maintenance…

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Programming

Speeding Up Emacs Startup with Daemon Mode and Native Compilation
ByEric Ma Mar 24, 2018Apr 11, 2026

Emacs startup time matters when you’re opening files frequently from the command line or in scripts. A few targeted optimizations can reduce perceived startup overhead from seconds to near-instant. Run Emacs as a daemon with emacsclient The most effective optimization is the server/client architecture. Start Emacs once as a daemon, then reuse that instance for…

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Programming

Configuring xterm for CJK Character Display
ByEric Ma Mar 24, 2018Apr 11, 2026

If xterm displays Chinese, Japanese, or Korean characters as empty boxes or rectangles, the problem is almost always a missing or improperly configured font with CJK glyphs. Configure fonts in ~/.Xresources xterm reads font configuration from ~/.Xresources. Add these lines: XTerm*utf8: 1 XTerm*locale: true XTerm*faceName: Noto Mono XTerm*faceSize: 11 XTerm*faceNameDoublesize: Noto Mono XTerm*dynamicColors: true The…

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Programming

SSH to Internal Hosts via Gateway
ByEric Ma Mar 24, 2018Apr 11, 2026

You have internal hosts on a private network (like 10.0.3.0/24) that aren’t directly accessible from your workstation. They sit behind a gateway (bastion host) like gateway.example.org. You need seamless SSH access to these internal IPs without manually hopping through the gateway each time. Using SSH ProxyJump The modern, straightforward approach is SSH’s built-in ProxyJump feature….

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Programming

Configuring Scala Compiler Options in sbt
ByEric Ma Mar 24, 2018Apr 11, 2026

When the Scala compiler emits warnings like deprecation notices, you need to pass compiler flags to see the details. The solution is to configure scalacOptions in your sbt build. Session-Only Configuration During an interactive sbt session, add options temporarily: set scalacOptions += “-deprecation” This applies only to the current session and is lost after reload…

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Programming

Taking Screenshots on Windows 7: A Practical Guide
ByEric Ma Mar 24, 2018Apr 11, 2026

The built-in Print Screen workflow is cumbersome — capture, open Paint, paste, crop, save. There are better approaches depending on your needs. Snipping Tool and Snip & Sketch On Windows 7, the Snipping Tool is available through the Start menu. Press the Windows key, type “snipping tool”, and launch it. You get basic capture modes:…

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Programming

Language Popularity Index Trends: What the Data Shows
ByEric Ma Mar 24, 2018Apr 11, 2026

Tracking programming language adoption helps inform hiring decisions, tool investment, and technology strategy. Several indices measure popularity across different dimensions — job postings, GitHub activity, Stack Overflow traffic, and search trends — so no single metric tells the complete story. TIOBE Index The TIOBE Index ranks languages based on search engine results, counting hits across…

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