bash

All posts tagged bash by Linux Bash
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    Learn how to host multiple websites on a single Linux server by running multiple Apache instances with distinct configurations using Bash. This approach offers improved application isolation, enhanced security, and tailored resource allocation, facilitating efficient server management. Follow a step-by-step guide covering Apache installation, configuration duplication, service file creation, and final validation for effective multi-instance management.
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    Learn how to create a password-protected directory in Linux using the Apache server, `.htaccess`, and `.htpasswd`. This tutorial guides you from installing Apache and necessary utilities, through setting up directories and password files, to configuring server settings and testing your configuration for secure data access.
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    This guide explores optimizing WordPress performance on a Linux server using Apache. Key approaches include enabling compression and browser caching, tuning WordPress configurations, and optimizing the MySQL database. Additionally, it covers automating maintenance with Bash scripts, all aimed at enhancing site speed, user experience, and SEO rankings.
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    This article guides Linux developers on enabling CORS (Cross-Origin Resource Sharing) on their servers using Bash scripting. It details CORS configuration steps for Apache and Nginx, including editing server files and adding necessary headers. Additionally, it covers testing CORS settings with tools like curl and automating configurations through Bash scripts, ensuring smooth functionality for web applications accessing resources across different domains.
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    This article explains how to accurately log client IP addresses from the `X-Forwarded-For` header in environments using proxies, utilizing Linux Bash. It covers the basics of the header, parsing methods using Bash, and addresses challenges such as IP spoofing and multi-IP headers to enhance security and user privacy in web development and system administration.
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    This article provides a detailed guide on creating and configuring self-signed SSL certificates in Linux using Bash. It covers why self-signed certificates are beneficial for development and testing environments, and outlines essential steps including generating a private key, creating the SSL certificate with OpenSSL, and configuring web servers like Apache and Nginx to use these certificates. Practical command-line examples are provided to help users set up and secure their server communications.
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    The article discusses the use of the `` directive in Apache to improve server security by restricting HTTP methods like POST, PUT, and DELETE. By setting limits on these methods, administrators can prevent unauthorized actions and optimize server performance. It outlines how to implement these configurations using Bash, highlights common use cases, and suggests best practices for security enhancements in server setups.
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    The article examines the versatile roles of the hyphen "-" in Linux Bash, illustrating its use in command options, file handling, and data redirection. It explains how hyphens modify command behaviors, represent standard input/output in redirection, and act as placeholders in file descriptors and data streams. Examples and a Bash script highlight its practical applications in enhancing command functionality and script efficiency in Linux.
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    This blog post explores the Shellshock vulnerability (CVE-2014-6271) in Bash, used extensively in Unix-based systems. It demonstrates how attackers can execute arbitrary commands via Bash's environment variables and provides a script for safe, controlled exploitation. The article emphasizes the importance of updating Bash for security.
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    The article explores using Bash co-processes and netcat (nc) to set up a real-time, bidirectional chat system. It details how co-processes facilitate asynchronous command execution that interacts seamlessly with the main script. By using `nc`, it explains setting up connection points for the chat, and employing the `coproc` command to manage simultaneous message exchanges effectively, enhancing scripting capabilities in Linux.
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    The blog article describes using the Bash command `yes | tr \n x` to generate an infinite string until memory overload. It breaks down the `yes` command which repetitively outputs 'y', and the `tr` command which replaces newlines with 'x', forming a continuous 'yx' output. It emphasizes understanding the impact on system resources and includes a sample script for safely demonstrating the command without crashing the system.
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    The blog delves into controlling GPIO pins in Linux via the `sysfs` interface, explaining its use in user space for simple file operations on pins. Steps covered include exporting the pin, setting its direction, and manipulating its state. The guide includes examples like LED control and a script for blinking an LED, highlighting the ease and effectiveness of `sysfs` for basic hardware interfacing.
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    This blog article explains how to intentionally trigger a segmentation fault in Bash to test signal handling capabilities. It details creating a simple C program that accesses forbidden memory to cause a segfault, which is then compiled and executed from a Bash script. The script uses `trap` to manage the `SIGSEGV` signal, illustrating how to handle errors gracefully and improve software robustness by using Bash in conjunction with lower-level operations.
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    The blog post explores the `FUNCNAME` array in Bash, highlighting its importance in debugging by tracing function call sequences. It shows how `FUNCNAME` aids in understanding script execution paths and function hierarchies, enhancing script management and error diagnosis for both novice and experienced scripters. Various examples demonstrate its practical applications in real-world scripting scenarios.
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    The blog explores Bash's `compopt` builtin which allows dynamic modification of autocomplete options on the command line. By detailing features that enable the tailoring of behaviors, such as limiting file completions to `.txt` files and controlling spaces after completions, `compopt` is shown to significantly enhance user efficiency. Examples and script implementation advice offer practical insights for power users and system administrators.
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    The article explains side effects in Bash arithmetic expressions, particularly how pre-increment (`++i`) and post-increment (`i++`) operators affect a variable's value and the outcome of expressions. It highlights the importance of understanding these effects for efficient script writing in Bash, offering a detailed example and a script to demonstrate these concepts in action.
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    In Bash scripting, memory allocation plays a crucial role in script performance and reliability. Normally, Bash uses `mmap()` for large memory blocks, but it can be configured to use `malloc()`, which helps reduce virtual memory fragmentation and may enhance performance on some systems. Setting the `MALLOC_MMAP_THRESHOLD_` environment variable to 0 directs `malloc()` to never utilize `mmap()` for memory allocation. This adjustment is demonstrated through a sample script that showcases memory allocation in varied operations.
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    The article delves into advanced Bash debugging with `shopt -s extdebug` and `declare -ft`, tools that enhance script debugging by enabling detailed function tracing and execution flow tracking. It includes practical examples showing how these tools help in troubleshooting and improving script performance, making them indispensable for Bash developers.
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    The article details how to use `bash` scripts for real-time monitoring of `sudo` command usage by parsing the `/var/log/secure` file on Linux. It highlights the use of `tail` and `awk` to dynamically track and respond to `sudo` invocations, enhancing security and user accountability. A sample script is provided to demonstrate instant notification of `sudo` activities.
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    Discover how to create a basic port scanner using Linux's `/dev/tcp` and the `timeout` command in this blog post. The `/dev/tcp` pseudo-device facilitates direct TCP socket interactions from the Bash shell, enabling users to assess port availability. The post showcases how to manage connection timeouts with the `timeout` command to make scanning efficient and provides a script that demonstrates detecting open ports on specified host and port range.
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    This article details how to generate a Time-based One-Time Password (TOTP) token using Bash, `openssl`, and `date +%s`. It clarifies TOTP's role in two-factor authentication by combining a secret key and the current time to produce a constantly updating password. Step-by-step, the article demonstrates creating a TOTP token with a Bash script and accentuates the importance of secure key management.
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    This blog explores using `iconv` for transliterating accented characters to ASCII in Linux Bash, focusing on text processing pipelines. `iconv` converts text to various encodings, simplifying tasks like sorting or searching in ASCII-only systems. Examples include transliterating French text in the terminal or via scripts, enhancing text compatibility and handling diversity in characters and languages.
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Discover how to explore the contents of Linux software packages without installing them. This insightful guide for developers and tech experts details methods using popular package managers like `apt`, `dnf`, and `zypper`. Learn to download and unpack `.deb` and `.rpm` packages to inspect contents, ensuring security, custom installations, or gaining educational insights with tools like `dpkg-deb`, `rpm2cpio`, and `cpio`. Ideal for those conducting security audits or exploring software packages across different Linux distributions.
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This blog details how to use Live USB and Rescue Mode for system recovery, essential tools for diagnosing and fixing corrupted systems. It covers creating a Live USB with tools like Rufus, booting in Rescue Mode, and step-by-step troubleshooting, making it invaluable for both IT professionals and casual users seeking to prevent data loss and manage system crises effectively.
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This article provides an in-depth look at the system requirements for several popular Linux distributions, including Ubuntu, Fedora, Debian, Arch Linux, Linux Mint, and Raspberry Pi OS. It is designed to help users match their hardware with the appropriate Linux distro, ensuring optimal performance. The guide covers CPU, RAM, and storage needs for each distribution and offers additional resources for further information.
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Learn how to configure HTTP/3 with Apache, leveraging the new QUIC protocol for improved web performance. This guide covers the installation of Apache and the experimental mod_http3, adjustments for QUIC protocol support, and firewall settings for UDP traffic on port 443. Despite being challenging due to limited native support, adopting HTTP/3 can significantly better your site's reliability and speed.
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Discover 24 Linux desktop environments in this comprehensive guide on LinuxBash.sh, perfect for both expert system administrators and newcomers. It explores popular options like GNOME, KDE Plasma, and less known ones like Enlightenment and Budgie, detailing their customization, efficiency, appearance, and system demands. Find installation tips and insights into each environment's relevance and popularity to choose the best desktop for your computing needs based on specific user requirements and hardware capabilities.
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Learn to tidy up Linux systems by managing unnecessary packages and dependencies via popular package managers like APT, DNF, and Zypper. The guide covers critical steps such as updating lists, upgrading packages, and safely removing unneeded dependencies, enhancing system efficiency. Practical tips and additional resources for deeper understanding are also provided.
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This article delves into the practice of package pinning in APT, a key tool in Debian and Ubuntu for prioritizing certain package versions during updates, ensuring system stability. Detailed steps for setting pin preferences in `/etc/apt/preferences` are provided, alongside comparisons with other package managers like DNF for Fedora and Zypper for openSUSE, highlighting their unique approaches to package prioritization.
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This article explains how to utilize `i2c-tools` for managing I2C devices on Linux systems. It begins with an introduction to the importance of `i2c-tools` for debugging I2C buses and devices, followed by installation guidelines across various Linux distributions. The piece details procedures for detecting I2C buses and devices, and demonstrates reading and writing to I2C devices using `i2cget` and `i2cset`. An example script is provided, illustrating how to read temperature from a sensor and configure a register, underscoring the tools' ease and efficiency for embedded system management.
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This article delves into Overlay Filesystems (OverlayFS), a union filesystem that combines read-only and writable layers for efficient file management in Linux environments. Ideal for scenarios involving containers or immutable systems, it explains the set-up and benefits, such as improved efficiency and space savings, providing instructions and real-world examples including its application in Docker.
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This comprehensive guide explains how to automate the installation of security updates on Ubuntu using the `unattended-upgrades` package, ensuring your system's maintenance with minimal manual intervention. It covers installation, configuration, and detailed commands to keep your system updated. The article also touches on update automation for other Linux distributions using tools like `dnf` and `zypper`.
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This guide explains how to install a free Let’s Encrypt SSL certificate on a Linux server using Certbot. It covers updating your package manager, installing Certbot, running it to obtain and set up your certificate, enabling automatic renewals, and ensuring your firewall allows HTTPS traffic. By following these steps, you can enhance your website’s security through HTTPS encryption.
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Discover how to use `losetup` for managing loopback devices in Linux. This guide covers the essentials, from setting up and attaching disk images with `losetup` to manipulating these virtual disks for tasks like system recovery and software testing. Learn to adjust settings for specific segments of disk images and effectively manage mounted file systems. Ideal for enhancing your skills in Linux system administration.
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This guide details how to build DEB packages from source for Debian-based systems, covering necessary tool setups like `dpkg-dev` and `build-essential`. It provides a step-by-step process for downloading, modifying, and building DEB files, tips for installing and managing these packages across various Linux package managers, and includes resources for further mastery of DEB package creation and maintenance.
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