Articles

Task State Analysis

October 25, 2026
Linux Notes
EN

Task-state analysis is a way to understand what processes and threads are doing by looking at their runtime states...

Shells and Bash Configuration

October 25, 2026
Linux Notes
EN

A Unix shell is a command-line program that lets a user communicate with the operating system. Instead of using buttons and menus, the user types commands, and the shell interprets those commands...

Performance Monitoring

October 25, 2026
Linux Notes
EN

Performance monitoring is the process of observing how a system uses its resources...

Managing Users

October 25, 2026
Linux Notes
EN

In Linux, user management is a crucial aspect of system administration. A user is essentially an entity that can log into the computer system and perform tasks based on the permissions granted to them. The Linux operating system stores user-related information in a couple of key files: /etc/passwd a...

Kernel

October 25, 2026
Linux Notes
EN

We will now delve deeply into the Linux kernel to understand its role in the operating system, where it resides on your system, and how kernel modules function. We will also explore how to download and examine the Linux kernel source code, and discuss the various configuration options available with...

Grep

October 25, 2026
Linux Notes
EN

The grep command is one of the most powerful and versatile tools in the Unix and Unix-like operating systems, including Linux and macOS. Its name stands for global regular expression print, and it is primarily used for searching plain-text data sets for lines that match a regular expression or a fix...

Containers and Docker

October 25, 2026
Linux Notes
EN

Containers have fundamentally changed the way software is built, shipped, and run. If you've spent time administering Linux systems, managing packages, configuring services, and troubleshooting dependency conflicts, you already understand the pain that containers were designed to solve. A container ...

Log Files and Journals

October 25, 2026
Linux Notes
EN

Understanding how logging works in Linux is like learning the language your system uses to communicate. Logs are the detailed records that your system keeps about its activities, and they are invaluable for troubleshooting, monitoring performance, and ensuring security. Let's embark on a journey to ...

Environment Variable

October 25, 2026
Linux Notes
EN

In Unix-style shells, variables let you store and reuse pieces of information, such as your preferred editor...

Permissions

October 25, 2026
Linux Notes
EN

File permissions are crucial in any Unix-like operating systems, including Linux, which employ several mechanisms for controlling access to files and directories. These mechanisms include standard permissions, special permissions, and access control lists (ACLs)...

Ldap

October 25, 2026
Linux Notes
EN

LDAP stands for Lightweight Directory Access Protocol...

Sed and Awk

October 25, 2026
Linux Notes
EN

sed (Stream Editor) and awk are powerful command-line utilities that originated from Unix and have become indispensable tools in Unix-like operating systems, including Linux and macOS. They are designed for processing and transforming text, allowing users to perform complex text manipulations with s...

Partitions

October 25, 2026
Linux Notes
EN

Partitioning a disk involves dividing a physical storage device into separate, manageable sections called partitions. Each partition functions as an independent disk within the operating system, allowing for better organization, multi-boot setups, or separation of system files from user data. The tw...

File System

October 25, 2026
Linux Notes
EN

In Unix, files and filesystems are important components of the operating system's structure. A file is a collection of data stored on disk, which can include anything from text documents and images to executable programs. Files are organized within directories in a hierarchical structure, allowing f...

Ports

October 25, 2026
Linux Notes
EN

In computer networking, ports serve as endpoints for communication between devices, similar to doors through which data flows in and out of a computer. In today's interconnected digital landscape, network security is paramount. Network ports are critical points that require diligent management and s...

Nfs

October 25, 2026
Linux Notes
EN

NFS stands for Network File System...

Running Executables

October 25, 2026
Linux Notes
EN

When you type a command such as...

Hardware

October 25, 2026
Linux Notes
EN

Linux is well known for running on a wide range of hardware. It can run on laptops, desktops, servers, embedded systems, routers, single-board computers, virtual machines, and high-performance clusters...

Pipe and Redirect

October 25, 2026
Linux Notes
EN

Input redirection (<) allows a command to read from a file, while output redirection (>) sends a command's output to a file. Streams like stdin, stdout, and stderr control the flow of data between commands and the system, where stdin is the input, stdout is the standard output, and stderr is the err...

Finding Files

October 25, 2026
Linux Notes
EN

The find, locate, and which commands are commonly used for file search operations. The find command performs a comprehensive search using attributes such as name, size, and type. locate provides a faster, albeit periodically updated, search by filename. which locates the path of a program's executab...

Disk Usage

October 25, 2026
Linux Notes
EN

Managing and monitoring disk usage is necessary for server maintenance, allowing administrators to identify disk space shortages caused by large log files, such as Apache or system logs, and malfunctioning applications that generate excessive data. Tools like df provide quick overviews of available ...

Package Managers

October 25, 2026
Linux Notes
EN

Debian and Ubuntu are popular Linux distributions for home users. These distributions and their derivatives use the Advanced Package Tool (APT). Other distributions use alternative package managers, like DNF, YUM, Pacman, which have unique functionalities and syntax...

Multiple Comparisons

October 25, 2026
Statistics Notes
EN

When conducting multiple hypothesis tests, the probability of making at least one Type I error—falsely rejecting a true null hypothesis—increases. This is known as the multiple comparisons problem or, in some contexts, the look-elsewhere effect...

Type i and Type Ii Errors

October 25, 2026
Statistics Notes
EN

Hypothesis testing allows researchers to evaluate claims about a population using sample data. We begin with a null hypothesis, H₀, which represents the claim being tested, and an alternative hypothesis, H_a, which represents a competing claim. Because decisions are based on sample data, errors are ...

Analysis of Categorical Data

October 25, 2026
Statistics Notes
EN

The chi-square (χ²) test is a family of statistical tests for categorical count data. These tests compare observed frequencies with the frequencies expected under a null hypothesis...

Confidence Intervals

October 25, 2026
Statistics Notes
EN

A confidence interval is the output of a sample-based procedure designed to cover a fixed population or model parameter at a stated rate over repeated samples. It supplements a point estimate with uncertainty under the sampling model. The interval's interpretation depends on that procedure and its a...

Hypothesis Testing

October 25, 2026
Statistics Notes
EN

A hypothesis test compares an observed statistic with its distribution under a specified null model. A difference matters statistically when it is large relative to the variation that model predicts, rather than simply large in raw units. Applications include comparing treatments, checking productio...

Null Hypothesis

October 25, 2026
Statistics Notes
EN

Statistical hypothesis testing is a method for using sample data to make inferences about a population. Understanding null and alternative hypotheses, along with how p-values are calculated and interpreted, is essential for applying hypothesis tests correctly...

Point Estimation

October 25, 2026
Statistics Notes
EN

A parameter is an unknown feature of a population or statistical model, such as a mean μ, variance σ², probability p, or regression coefficient β. A point estimator is a rule or statistic computed from sample data and used to estimate that parameter...

Axioms of Probability

October 25, 2026
Statistics Notes
EN

Probability theory is built on a small set of principles, called axioms, that define how probability measures behave. These axioms, formalized by the Russian mathematician Andrey Kolmogorov, provide the foundation for the rules used throughout probability theory...

Geometric Probability

October 25, 2026
Statistics Notes
EN

Geometric probability describes random outcomes represented by locations, directions, lengths, or shapes. Under a uniform model, probability is proportional to the relevant geometric measure, such as length on a line or area in a plane. The sampling mechanism determines that measure: uniform angle, ...

Total Probability

October 25, 2026
Statistics Notes
EN

The law of total probability computes an event's overall probability by separating the possible cases that can produce it. The cases must be disjoint and cover the sample space, so every outcome contributes exactly once. Within each case, multiply the event's conditional probability by the chance of...

Bayes Theorem

October 25, 2026
Statistics Notes
EN

Bayes' theorem reverses the direction of a conditional probability. It connects the chance of evidence under a proposed event, P(B | A), with the chance of that event after seeing the evidence, P(A | B). These quantities use different reference groups. Updating requires both the evidence rate within...

Conditional Probability

October 25, 2026
Statistics Notes
EN

Conditional probability changes the reference set after information is supplied. In P(A | B), we retain outcomes in B and ask what fraction of their probability also lies in A. The vertical bar means “given”; it does not require B to happen earlier in time or cause A. The multiplication rule reverse...

Introduction to Probability

October 25, 2026
Statistics Notes
EN

A probability model specifies possible outcomes and assigns probabilities to events made from those outcomes. The sample space tells us what can happen; the probability law tells us how likely those possibilities are. Listing outcomes does not make them equally likely. For example, two fair dice hav...