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 simplify YAML file manipulation with `yq`, an intuitive command-line tool designed for streamlined processing of YAML configurations. This guide covers installation on Linux distributions like Ubuntu, Fedora, and openSUSE, and usage examples such as reading, modifying, and merging YAML data. Ideal for developers and system administrators, `yq` maintains original file formatting and provides a powerful alternative to manual editing. Explore its features at [LinuxBash.sh](https://www.linuxbash.sh/post/yq-process-yaml-files-with-ease).
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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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Discover how to manage and manipulate environment variables in Bash efficiently. This guide covers the essentials of setting, viewing, and unsetting these variables, as well as their scope and influence on your scripting work. Perfect for developers and system administrators, the article includes step-by-step instructions and examples to help you master environment variables for better script customization and Linux environment management.
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Learn to set up a DHCP server on Linux with instructions on installing and configuring it across various distributions using apt, dnf, and zypper. The guide covers DHCP package installation, dhcpd.conf file setup, IP, DNS, and subnet configurations, ensuring correct IP assignments and reducing manual setup errors for better network management. Further resources provide in-depth information on DHCP setup specifics.
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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 guide offers comprehensive instructions on how to mount NFS and SMB network filesystems in Linux, from installing necessary packages to configuring server-client relationships. It covers best practices for efficient file sharing and management across systems using NFS and SMB protocols, along with tips for secure and persistent mounting, editing configuration files, and troubleshooting advice to ensure optimal performance and security. Ideal for beginners and experienced users alike.
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Explore the benefits and setup process of autossh, a tool that maintains stable SSH connections. Ideal for remote work and server management over unstable networks, autossh automatically restarts SSH sessions after disconnections. This guide covers installation across various Linux distributions like Ubuntu, Fedora, and openSUSE, and provides usage examples with minimal configuration. Perfect for ensuring persistent remote access, autossh enhances your SSH environment seamlessly.
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This blog post on LinuxBash.sh is a comprehensive guide to trapping and handling signals in Bash scripts, crucial for ensuring script reliability. It details signal trapping, covers common signals like SIGINT and SIGTERM, and provides examples of the `trap` command for setting up handlers. The article is valuable for those looking to improve script safety and includes sections on package installations for handling tools across various Linux package managers. Further reading links are also provided.
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This article delves into UNIX/Linux special permission bits—SUID, SGID, and the Sticky Bit. It explains how SUID lets a file execute with the file owner’s permissions, SGID allows execution with the group's permissions, and the Sticky Bit restricts file deletion in shared directories. It covers their applications, security risks, and crucial role in enhancing multi-user system security and functionality.
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Learn to master AppStream on RHEL-based systems for flexible software management. This guide details how to use the `dnf` package manager to search, install, switch, and remove modular packages, providing strategies for managing multiple software versions across various platforms, including Debian/Ubuntu with `apt` and openSUSE with `zypper`. Essential for improving system stability and flexibility.
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Learn how to monitor and test disk health in Linux using `smartctl`, a tool from the `smartmontools` package. The guide details installing the tool across distributions like Debian, Ubuntu, Fedora, and openSUSE, and explains how to enable SMART, perform health checks, interpret the data, and integrate monitoring into regular system maintenance to prevent data loss and improve performance. Ideal for IT professionals aiming to enhance data integrity and system reliability. Further resources for advanced practices are also provided.
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Learn how to expand your Red Hat Enterprise Linux (RHEL)-based system's software library by enabling the Extra Packages for Enterprise Linux (EPEL) repository. Our guide offers step-by-step instructions on installing EPEL using `yum` or `dnf`, enhancing system capabilities by accessing a broader range of applications and tools not available in the default repositories.
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Discover how to access real-time weather updates directly from your Linux terminal using `wttr.in`. This web service allows users to fetch weather forecasts via simple terminal commands like curl or wget, featuring results in ASCII art. Perfect for developers and sysadmins, it integrates easily into scripts and supports multiple locations, enhancing productivity within the command-line interface.
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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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