Email sender fraud remains a persistent problem in email infrastructure. Attackers send messages spoofing legitimate domains, damaging sender reputation and causing rejected mail that creates administrative overhead. SPF, DKIM, and DMARC are DNS-based authentication standards designed to verify email senders and prevent domain spoofing. Sender Policy Framework (SPF) Sender Policy Framework (SPF) is a DNS-based…
R handles JSON data effectively through packages designed for parsing and manipulating structured data. The most practical approach for fetching JSON from REST APIs is using the jsonlite package. Install and load jsonlite Install the package once: install.packages(“jsonlite”) Load it in your R session: library(jsonlite) Fetch JSON from a REST API Use fromJSON() to retrieve…
Excel files remain a common data format you’ll encounter. The readxl package handles both .xls and .xlsx formats efficiently without external dependencies, making it the standard choice for Excel import in R. Installation Install the package once per R environment: install.packages(“readxl”) Load it in your session or script: library(readxl) Basic Import The read_excel() function handles…
LibreOffice is the most reliable tool for command-line document conversion, offering robust support for Microsoft Office formats. Install it on Ubuntu/Debian/Linux Mint: sudo apt install libreoffice On Fedora/RHEL systems: sudo dnf install libreoffice For minimal headless-only installations without GUI dependencies: sudo apt install libreoffice-writer libreoffice-calc libreoffice-impress Converting .docx/.doc to .odt LibreOffice runs in headless mode…
Hex-encoded strings are common in system administration, debugging, and network packet analysis. Whether you’re examining binary data, decoding network protocols, or troubleshooting data encoding issues, you’ll often need to convert between hex and ASCII representations. xxd is the standard tool for this task on Unix-like systems. It creates hexdumps and reverses them back to binary…
Linux 5.4.72 is a stable kernel update containing 23 commits and approximately 126,508 lines of code changes compared to the base 5.4 release. This release focuses on critical security and stability fixes across cryptography, filesystem, USB, Bluetooth, and architecture-specific code paths. Cryptography and Security Fixes QAT cipher validation Added length validation for AEAD AES-CBC-HMAC operations…
The simplest way to install R on macOS is through Homebrew: brew install r If you don’t have Homebrew installed, install it first from https://brew.sh. Verify the installation by launching R from the terminal: R You should see the R version and prompt. To verify everything works, run a quick demo: demo(graphics) q() Type n…
Start by updating your package manager and installing R: sudo apt update sudo apt install r-base This installs the base R distribution from Ubuntu’s default repositories. For more details on R installation, see the dedicated R installation guide. Install RStudio Desktop Once R is installed, you can add RStudio Desktop as your local IDE. Download…
R is a language and environment for statistical computing and graphics. It’s free software under the GPL license and provides extensive statistical and graphical capabilities through numerous contributed packages. The R environment package is available in Ubuntu’s standard repositories. Install it with: sudo apt update sudo apt install r-base This installs r-base along with recommended…
Linux kernel 4.19.70 is a stable release containing 95 fixes and improvements across multiple subsystems. This release addresses critical issues in audio, networking, storage, virtualization, DMA handling, and various device drivers. Major Fixes Audio and Sound ALSA USB Audio Improvements The release includes several USB audio enhancements. A quirk was added for Behringer UFX1604 to…
Counting words in a file is a straightforward task in PHP, but the approach varies depending on file size and memory constraints. Here are the most practical methods. Simple Approach with str_word_count() For small to medium files, load the entire file and use str_word_count(): $content = file_get_contents(‘myfile.txt’); $wordCount = str_word_count($content); echo “Total words: $wordCount\n”; This…
Google shut down Feedburner’s management interface, leaving it in indefinite maintenance mode. While RSS remains a critical format for feed distribution across platforms like WordPress and other CMS software, you need an alternative service for feed management and subscriber tracking. follow.it is a solid Feedburner replacement that handles RSS feeds, subscriptions, and analytics. This guide…
Wayland screen recording has matured significantly. Here are the tools that actually work well in 2026, with their tradeoffs and setup. GNOME Built-in Screen Recording GNOME 40+ includes integrated screen recording on Wayland. Press Ctrl+Alt+Shift+R to start. A red dot appears in the top-right corner. Press the same shortcut again or click the indicator to…
The built-in pdb module is Python’s equivalent to gdb — a command-line debugger that lets you step through code, set breakpoints, inspect variables, and control execution flow. It’s essential for server-side debugging and situations where IDE graphical debuggers aren’t available. Starting a pdb Session Run a script through pdb directly: python -m pdb prog.py arg1…
The up arrow works, but it’s tedious for finding commands from weeks ago. Bash offers several practical methods to search your history efficiently. Built-in Incremental Search: Ctrl + R Press Ctrl + R to enter reverse-search mode. Type any part of the command you remember: (reverse-i-search)`docker’: docker ps -a Bash displays the most recent match….
Sometimes you have a global gitignore rule—like ignoring all *.log files—but need to track one specific exception. Git lets you negate patterns using the ! character. # Ignore all log files *.log # But DO track this one specific file !important.log Pattern matching is evaluated top-to-bottom, and the last matching pattern wins. Your negation rule…
Python’s str.split() method splits a string by a separator and returns a list. Here are the common patterns: “a string separated by space”.split() # [‘a’, ‘string’, ‘separated’, ‘by’, ‘space’] “a,string,separated,by,comma”.split(“,”) # [‘a’, ‘string’, ‘separated’, ‘by’, ‘comma’] Note that calling split() without arguments splits on any whitespace and automatically removes empty strings. Handling consecutive separators When…
[md] The error ValueError: zero length field name in format occurs when using implicit positional arguments in .format() strings with Python versions that don’t support this syntax. ## The Problematic Code print(‘== {} SPF’.format(d)) This raises ValueError: zero length field name in format on older Python interpreters. ## Why This Happens The {} syntax without…
The error “Cannot make directory ‘/var/run/screen/S-apache’: Permission denied” typically means the screen session directory can’t be created under /var/run/screen/. This happens when screen lacks proper permissions or when security policies block the operation. Verify screen installation and permissions First, confirm screen is installed with correct permissions: $ ls -la $(which screen) -rwxr-sr-x 1 root screen…
Several methods exist to prepend a prefix string to each line of text. The right approach depends on your input source and performance requirements. Using sed The sed stream editor is the most portable and efficient approach: sed ‘s/^/PREFIX/’ file.txt This uses a substitution command where ^ matches the start of each line and PREFIX…