Go doesn’t have a dedicated FileExists() function. Instead, use os.Stat() to retrieve file metadata and inspect the error type to determine what actually happened. Basic File Existence Check import “os” func fileExists(path string) bool { _, err := os.Stat(path) return !os.IsNotExist(err) } os.Stat() returns an error only if something goes wrong. The key is using…
Both FS_IOC_GETFLAGS and FS_IOC_FSGETXATTR retrieve inode attributes, but they differ in scope, design, and what they’re meant to expose. Understanding which to use depends on your filesystem, compatibility requirements, and what metadata you actually need. Historical context and design constraints FS_IOC_GETFLAGS originated with ext2/ext3 as a simple interface to query inode flags. It became so…
Local port forwarding on the same host requires understanding how netfilter processes packets based on their origin. The critical distinction: traffic from external sources hits the PREROUTING chain, but packets originating locally traverse the OUTPUT chain instead. Miss either one, and your forwarding won’t work. The core problem When you forward UDP port 500 to…
The simplest way to convert a string to lowercase is using the lower() method: >>> “Hello World”.lower() ‘hello world’ >>> “ABC”.lower() ‘abc’ >>> “abc”.lower() ‘abc’ The lower() method returns a new string with all uppercase characters converted to lowercase. The original string remains unchanged — strings are immutable in Python. Basic Usage text = “Python…
Traditionally, tools like strace used ptrace to monitor system calls. While effective for development debugging, ptrace stops the entire process for every syscall, causing 2-10x slowdown. This makes it unsuitable for production workloads where you need real-time visibility without tanking performance. Modern Linux offers significantly faster alternatives through eBPF (Extended Berkeley Packet Filter), which runs…
bbPress is WordPress’s standard forum plugin. When you need to modify how forum topics, replies, or other content displays, you’ll use WordPress filter hooks to intercept and transform the content before it reaches users. Common bbPress Content Filters Filtering Topic Content The bbp_get_topic_content filter runs after topic content is retrieved from the database but before…
PHP lets you call functions dynamically when you don’t know the function name until runtime. This is essential for plugin systems, routing handlers, API dispatchers, and configuration-driven logic. The approach you choose affects both performance and safety. Direct Variable Function Invocation The simplest approach treats a string variable as a callable: $func = ‘strlen’; echo…
Sparse files optimize storage by storing only metadata for contiguous zero-filled ranges instead of allocating actual disk blocks. They’re essential for VM images, virtual block devices, and large databases where much of the allocated space remains unused. Most modern filesystems support sparse files: ext4, btrfs, and XFS on Linux; NTFS on Windows; and APFS on…
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…
iptables remains the standard firewall interface across most Linux distributions, though it’s technically a compatibility layer over nftables. Whether you’re managing legacy systems or prefer the familiar syntax, here’s what you need to know. Basic Command to Open a Port The fundamental syntax to allow inbound traffic on a specific port: sudo iptables -A INPUT…
When you need additional swap space but all partitions are allocated, creating a swap file lets you add capacity without repartitioning. This is especially useful on systems with fixed disk layouts or cloud instances where you can’t modify the underlying disk structure. Creating the Swap File Start by allocating space. fallocate is the fastest option…
Intercepting traffic before normal routing decisions requires understanding packet flow through iptables chains. If you need incoming packets to bypass the INPUT chain and process through FORWARD instead, you’ll use the PREROUTING chain with Destination NAT (DNAT). Packet Flow Through iptables When a packet arrives at your system, it traverses these chains in order: PREROUTING…
In Linux, everything is a file—including hardware devices. Block devices like disks, SSDs, and USB drives appear as files in /dev and handle I/O in fixed-size blocks. You need reliable ways to detect them in your Python scripts, especially when automating storage operations. Using pathlib (Recommended) Python 3.4+ provides pathlib.Path.is_block_device(), which is the modern standard:…
When you need to load configuration files, data files, or assets relative to your script’s location, the current working directory won’t work — it depends entirely on where you called the script from, not where the script actually lives. Use pathlib.Path: from pathlib import Path # The directory where the script lives script_dir = Path(__file__).resolve().parent…
The stat() system call is the traditional approach for checking file existence: #include <sys/stat.h> int file_exists(const char *path) { struct stat buffer; return (stat(path, &buffer) == 0); } This returns 1 if the file exists, 0 otherwise. The stat() call fills the buffer with file metadata, but when checking existence alone, you’re mainly interested in…
The Control Center in iOS provides the quickest way to toggle wireless connections. Here’s what you need to know across iOS versions. Accessing Control Center On modern iPhones with Face ID (iPhone X and later), swipe down from the top-right corner of the screen. On iPhones with a Home button (iPhone 8 and earlier), swipe…
MPlayer reached end-of-life in 2010 and hasn’t received updates since. If you’re still using it, you’re missing years of improvements in video decoding, filtering, and performance. For new projects, use mpv instead—it’s the maintained fork that incorporates MPlayer’s codebase with significant enhancements. That said, if you’re stuck maintaining legacy MPlayer setups, here’s how to optimize…
URL encoding (percent-encoding) converts special characters into a format safe for transmission over HTTP. In Python, the urllib.parse module provides straightforward functions for decoding these strings. Basic Decoding with unquote The unquote() function is the standard approach: from urllib.parse import unquote encoded_url = “https://example.com/search?q=hello%20world” decoded_url = unquote(encoded_url) print(decoded_url) # Output: https://example.com/search?q=hello world This handles the…
/dev/shm is a tmpfs mount that allocates storage from your system’s RAM rather than disk. It’s commonly used for inter-process communication (IPC), shared memory segments, and temporary data that needs low-latency access. By default, Linux allocates half your total RAM to /dev/shm, but you’ll often need to adjust this for specific workloads. Checking Current Size…
Patch files are essential for projects that use email-based code review or maintainer-driven workflows. They’re especially common in Linux kernel development, embedded systems, and projects that don’t rely on pull requests. Creating a patch from a single commit The standard approach is git format-patch: git format-patch -1 <commit-hash> This creates a .patch file containing the…