The Unix epoch (seconds since January 1, 1970 UTC) is the standard for representing time across systems. Perl gives you straightforward access to this value. Basic epoch timestamp The simplest way to get the current epoch time: my $epoch = time(); print $epoch; # prints something like 1735689600 The time() function returns an integer representing…
Getting the current epoch timestamp is straightforward using the time package: package main import ( “fmt” “time” ) func main() { epoch := time.Now().Unix() fmt.Println(epoch) } The time.Now().Unix() call returns the number of seconds since January 1, 1970 UTC as an int64. Getting nanosecond precision If you need higher resolution, use UnixNano() for nanoseconds since…
The epoch timestamp (also called Unix time) represents the number of seconds since January 1, 1970, 00:00:00 UTC. PHP provides several straightforward methods to obtain this value. Using time() The simplest approach is the time() function: <?php $timestamp = time(); echo $timestamp; // Output: 1704067200 (example) ?> This returns the current Unix timestamp as an…
There are two primary ways to access environment variables in Java: System.getenv() for reading variables and System.getProperty() for reading system properties. They’re different things, so understanding which one you need matters. Reading Environment Variables with System.getenv() System.getenv() retrieves variables set in your shell or container environment: String javaHome = System.getenv(“JAVA_HOME”); System.out.println(“JAVA_HOME: ” + javaHome); To…
Python offers several ways to get the current epoch timestamp, each suited to different use cases. The choice depends on your precision requirements and whether you’re working with timezone-aware operations. Using time.time() The simplest approach is time.time(), which returns the current time as a float representing seconds since the Unix epoch (January 1, 1970, 00:00:00…
Environment variables are essential for configuration management—API keys, database URLs, feature flags, and environment-specific settings should never be hardcoded. Python provides straightforward mechanisms to access them. The os Module The standard way to read environment variables is with the os module: import os api_key = os.environ[‘API_KEY’] This raises a KeyError if the variable doesn’t exist….
The standard sort command is single-threaded by default, which limits performance on modern multi-core systems. Several approaches exist to speed up sorting operations using parallelism. GNU Sort with Parallel Sorting Modern versions of GNU sort (8.23+) include built-in parallel sorting support. Enable it with the –parallel flag: sort –parallel=4 large_file.txt > sorted_output.txt The –parallel option…
Reading files line by line is a common task when handling large datasets, logs, or any text-based input where loading the entire file into memory isn’t practical. PHP provides several methods, each with different memory footprints and use cases. Using fgets() The most straightforward approach uses fgets() with a file handle: $file = fopen(‘large_file.txt’, ‘r’);…
Processing files line by line is a common task in systems programming, data processing, and log analysis. C++ provides several approaches with different trade-offs in performance, memory usage, and code clarity. Using std::getline with std::ifstream The most straightforward approach uses std::getline with an input file stream: #include <fstream> #include <string> #include <iostream> int main() {…
Java has several solid REPL implementations available. Here are the main options and how to use them. jshell (Official) The best choice for most users is jshell, included in JDK 9+. It’s the official interactive shell for Java and comes with every modern Java installation. Start it immediately: jshell Basic usage: jshell> long ts =…
Go compiles quickly and go run handles small scripts, but a REPL is more practical for interactive testing and exploration. Here are the best options available today. gore gore remains the most mature Go REPL. It’s actively maintained and handles most interactive development workflows. Install it: go install github.com/motemen/gore/cmd/gore@latest Basic usage: $ gore gore version…
There are several ways to retrieve the hostname on a Linux system from Python. The choice depends on your use case and whether you need the simple hostname or the fully qualified domain name (FQDN). Using socket.gethostname() The simplest approach uses the socket module from the standard library: import socket hostname = socket.gethostname() print(hostname) This…
Reading a file line by line is memory-efficient and the standard approach for handling large text files in Python. The key is choosing the right method for your use case. The Iterator Approach (Recommended for Large Files) For most scenarios, especially with large files, use the file object as an iterator: with open(‘file.txt’, ‘r’) as…
When working with Hadoop Distributed File System (HDFS), files containing spaces in their names require special handling during the hdfs dfs -put command. Without proper escaping or quoting, the shell interprets spaces as delimiters, splitting the filename into multiple arguments. Direct Upload with Quoting The simplest approach is to wrap the filename in quotes: hdfs…
The most straightforward way to read an environment variable in Python is with os.getenv(): import os api_key = os.getenv(‘API_KEY’) print(api_key) If the variable doesn’t exist, getenv() returns None. You can provide a default value as a fallback: debug_mode = os.getenv(‘DEBUG’, ‘False’) port = os.getenv(‘PORT’, ‘8000’) For variables that must exist, use os.environ[] instead. This raises…
Use os.Getenv() to read an environment variable: package main import ( “fmt” “os” ) func main() { val := os.Getenv(“MY_VAR”) fmt.Println(val) } os.Getenv() returns an empty string if the variable doesn’t exist. This means you can’t distinguish between an unset variable and one explicitly set to an empty string. Checking if a variable exists To…
There are several ways to get a file’s size without importing the os module. Each approach has different use cases depending on your needs. Using pathlib.Path The most straightforward approach uses pathlib, which is part of the standard library: from pathlib import Path file_path = Path(‘example.txt’) size = file_path.stat().st_size print(f”File size: {size} bytes”) This is…
Go’s io.Reader interface is fundamental to working with streams of data. When you have a byte slice and need to pass it to a function expecting an io.Reader, the standard library provides straightforward solutions. Using bytes.NewReader The most direct approach is bytes.NewReader(), which wraps a byte slice in an io.Reader: package main import ( “bytes”…
Process priority management is essential for ensuring critical tasks get CPU resources when needed. Linux provides several mechanisms to control how the kernel scheduler allocates CPU time to processes. Understanding Priority Levels Linux uses two priority concepts: Nice value: ranges from -20 (highest priority) to 19 (lowest priority). Default is 0. Real-time priority: ranges from…
Linux powers most of the cloud infrastructure, supercomputers, and embedded systems globally. The field itself spans kernel development, system administration, performance tuning, networking, and DevOps. Researching systems effectively requires understanding where to look, what tools matter, and how to validate your findings against real-world constraints. Start With the Right Foundation Before diving into specific research,…