The Hacker News post titled "Show HN: Interactive systemd (a better way to work with systemd units)" introduces a new command-line tool called isd (Interactive Systemd) designed to simplify and streamline the management of systemd units. isd provides an interactive text-based user interface (TUI) built with Python and the curses library, offering a more intuitive and discoverable alternative to traditional command-line tools like systemctl.
The core functionality of isd revolves around presenting a dynamically updating list of systemd units within a terminal window. Users can navigate this list using keyboard controls (arrow keys, PgUp/PgDown) and perform various actions on selected units directly within the interface. These actions include: starting, stopping, restarting, enabling, disabling, masking, and unmasking units. The status of each unit (active, inactive, failed, etc.) is clearly displayed in real-time, providing immediate feedback on executed commands.
isd enhances the user experience by offering several features not readily available with standard systemctl usage. A built-in search functionality allows users to quickly filter the unit list by typing partial or full unit names. The interface also displays detailed information about a selected unit, including its description, loaded configuration file, and current status details. Additionally, isd includes a log viewer that streams the journal logs for a selected unit directly within the TUI, eliminating the need to switch between different terminal windows or commands to monitor unit activity.
The project aims to lower the barrier to entry for systemd management, especially for users less familiar with the command-line interface or the complexities of systemctl. By providing a visual and interactive environment, isd simplifies the process of managing systemd units, making it easier to monitor, control, and troubleshoot services and other system components. The project is open-source and available on GitHub, encouraging community contributions and further development. The post highlights the key benefits of using isd, emphasizing its interactive nature, real-time updates, integrated log viewer, and simplified workflow compared to traditional methods. It positions isd as a valuable tool for both novice and experienced system administrators.
The website "FFmpeg by Example" provides a practical, example-driven guide to utilizing the FFmpeg command-line tool for various multimedia manipulation tasks. It eschews extensive theoretical explanations in favor of presenting concrete, real-world use cases and the corresponding FFmpeg commands to achieve them. The site is structured around a collection of specific examples, each demonstrating a particular FFmpeg operation. These examples cover a broad range of functionalities, including but not limited to:
Basic manipulations: These cover fundamental operations like converting between different multimedia formats (e.g., MP4 to WebM), changing the resolution of a video, extracting audio from a video file, and creating animated GIFs from video segments. The examples demonstrate the precise command-line syntax required for each task, often highlighting specific FFmpeg options and their effects.
Audio processing: The examples delve into audio-specific manipulations, such as normalizing audio levels, converting between audio formats (e.g., WAV to MP3), mixing multiple audio tracks, and applying audio filters like fade-in and fade-out effects. The provided commands clearly illustrate how to control audio parameters and apply various audio processing techniques using FFmpeg.
Video editing: The site explores more advanced video editing techniques using FFmpeg. This encompasses tasks such as concatenating video clips, adding watermarks or overlays to videos, creating slideshows from images, and applying complex video filters for effects like blurring or sharpening. The examples showcase the flexibility of FFmpeg for performing non-linear video editing operations directly from the command line.
Streaming and broadcasting: Examples related to streaming and broadcasting demonstrate how to utilize FFmpeg for encoding video and audio streams in real-time, suitable for platforms like YouTube Live or Twitch. These examples cover aspects like setting bitrates, choosing appropriate codecs, and configuring streaming protocols.
Subtitle manipulation: The guide includes examples demonstrating how to add, remove, or manipulate subtitles in video files. This encompasses burning subtitles directly into the video stream, as well as working with external subtitle files in various formats.
For each example, the site provides not only the FFmpeg command itself but also a clear description of the task being performed, the purpose of the various command-line options used, and the expected output. This approach allows users to learn by directly applying the examples and modifying them to suit their specific needs. The site focuses on practicality and immediate application, making it a valuable resource for both beginners seeking a quick introduction to FFmpeg and experienced users looking for specific command examples for common tasks. It emphasizes learning through practical application and avoids overwhelming the reader with unnecessary theoretical details.
The Hacker News post for "FFmpeg by Example" has several comments discussing the utility of the resource, alternative learning approaches, and specific FFmpeg commands.
Many commenters praise the resource. One user calls it a "great starting point" and highlights the practicality of learning through examples. Another appreciates the clear explanations and the well-chosen examples which address common use cases. A third commenter emphasizes the value of the site for its concise and focused approach, contrasting it favorably with the official documentation, which they find overwhelming. The sentiment is echoed by another who found the official documentation difficult to navigate and appreciates the example-driven learning offered by the site.
Several comments discuss alternative or supplementary resources. One commenter recommends the book "FFmpeg Basics" by Frantisek Korbel, suggesting it pairs well with the website. Another points to a different online resource, "Modern FFmpeg Wiki," which they find to be more comprehensive. A third user mentions their preference for learning through man pages and flags, reflecting a more command-line centric approach.
Some commenters delve into specific FFmpeg functionalities and commands. One user discusses the complexities of hardware acceleration and how it interacts with different FFmpeg builds. They suggest static builds are generally more reliable in this regard. Another commenter provides a specific command for extracting frames from a video, demonstrating the practical application of FFmpeg. A different user shares a command for losslessly cutting videos, a common task for video editing. This sparks a small discussion about the nuances of lossless cutting and alternative approaches using keyframes. Someone also recommends using -avoid_negative_ts make_zero for generating output suitable for concatenation, highlighting a lesser-known but useful flag combination.
Finally, there's a comment advising caution against blindly copying and pasting commands from the internet, emphasizing the importance of understanding the implications of each command and flag used.
The blog post "Bad Apple but it's 6,500 regexes that I search for in Vim" details a complex and computationally intensive method of recreating the "Bad Apple" animation within the Vim text editor. The author's approach eschews traditional methods of animation or video playback, instead leveraging Vim's regex search functionality as the core mechanism for displaying each frame.
The process begins with a pre-processed version of the Bad Apple video. Each frame of the original animation is converted into a simplified, monochrome representation. These frames are then translated into a series of approximately 6,500 unique regular expressions. Each regex is designed to match a specific pattern of characters within a specially prepared text buffer in Vim. This buffer acts as the canvas, filled with a grid of characters that represent the pixels of the video frame.
The core of the animation engine is a Vim script. This script iterates through the sequence of pre-generated regexes. For each frame, the script executes a search using the corresponding regex. This search highlights the matching characters within the text buffer, effectively "drawing" the frame on the screen by highlighting the appropriate "pixels." The rapid execution of these searches, combined with the carefully crafted regexes, creates the illusion of animation.
To further enhance the visual effect, the author utilizes Vim's highlighting capabilities. Matched characters, representing the black portions of the frame, are highlighted with a dark background, creating contrast against the unhighlighted characters, which represent the white portions. This allows for a clearer visual representation of each frame.
Due to the sheer number of regex searches and the computational overhead involved, the animation playback is significantly slower than real-time. The author acknowledges this performance limitation, attributing it to the inherent complexities of regex processing within Vim. Despite this limitation, the project demonstrates a unique and inventive application of Vim's functionality, showcasing the versatility and, perhaps, the limitations of the text editor. The author also provides insights into their process of converting video frames to regex patterns and optimizing the Vim script for performance.
The Hacker News post titled "Bad Apple but it's 6,500 regexes that I search for in Vim" (linking to an article describing the process of recreating the Bad Apple!! video using Vim regex searches) sparked a lively discussion with several interesting comments.
Many commenters expressed amazement and amusement at the sheer absurdity and technical ingenuity of the project. One commenter jokingly questioned the sanity of the creator, reflecting the general sentiment of bewildered admiration. Several praised the creativity and dedication required to conceive and execute such a complex and unusual undertaking. The "why?" question was raised multiple times, albeit rhetorically, highlighting the seemingly pointless yet fascinating nature of the project.
Some commenters delved into the technical aspects, discussing the efficiency (or lack thereof) of using regex for this purpose. They pointed out the computational intensity of repeatedly applying thousands of regular expressions and speculated on potential performance optimizations. One commenter suggested alternative approaches that might be less resource-intensive, such as using image manipulation libraries. Another discussed the potential for pre-calculating the matches to improve performance.
A few commenters noted the historical precedent of using unconventional tools for creative endeavors, drawing parallels to other esoteric programming projects and "demoscene" culture. This placed the project within a broader context of exploring the boundaries of technology and artistic expression.
Some users questioned the practical value of the project, while others argued that the value lies in the exploration and learning process itself, regardless of practical applications. The project was described as a fun experiment and a demonstration of technical skill and creativity.
Several commenters expressed interest in the technical details of the implementation, asking about the specific regex patterns used and the mechanics of syncing the searches with the audio. This demonstrated a genuine curiosity about the inner workings of the project.
Overall, the comments reflect a mixture of amusement, admiration, and technical curiosity. They highlight the project's unusual nature, its technical challenges, and its place within the broader context of creative coding and demoscene culture.
This GitHub repository, titled "pseudo3d," showcases a remarkably concise implementation of a raycasting engine written entirely in Bash script. The provided code leverages the shell's built-in string manipulation capabilities and arithmetic functionalities to render a pseudo-3D perspective of a simple world map defined within the script itself. The world map is represented as a two-dimensional array of characters, where different characters signify different types of walls or empty space.
The core of the raycasting algorithm involves iterating through the screen's horizontal pixels, calculating the viewing angle for each pixel based on the player's position and viewing direction. For each pixel, a "ray" is cast from the player's position into the world map, effectively tracing a line until it intersects with a wall character. The distance to the wall intersection is then calculated using a simplified distance formula.
This distance value determines the height of the wall segment to be drawn on the screen for that particular pixel. Closer walls result in taller wall segments, creating the illusion of perspective. The rendering process utilizes ANSI escape codes to directly manipulate the terminal output, drawing vertical lines of varying heights representing the walls. Different wall characters in the map are visually distinguished by using different colors for the rendered wall segments, again achieved through ANSI escape codes. The rendering process updates the terminal output in real-time, providing a dynamic view as the player navigates the world.
The player's movement and rotation are handled through basic keyboard input. The script detects specific key presses, updating the player's position and viewing angle accordingly. This dynamic update combined with the real-time rendering loop creates an interactive experience where the player can explore the defined world from a first-person perspective. While rudimentary, the implementation successfully demonstrates the fundamental principles of raycasting in a surprisingly minimal and accessible manner using the Bash scripting environment. The code's brevity and reliance on built-in shell functionalities serve as a testament to the versatility and unexpected capabilities of the Bash scripting language beyond typical system administration tasks.
The Hacker News post titled "A Raycaster in Bash" (https://news.ycombinator.com/item?id=42475703) has generated several comments discussing the project, its performance, and potential applications.
Several commenters express fascination with the project, praising the author's ingenuity and ability to implement a raycaster in a language like Bash, which isn't typically used for such computationally intensive tasks. They admire the technical achievement and the demonstration of what's possible even with limited tools.
Performance is a recurring theme. Commenters acknowledge that the Bash implementation is slow, with some sharing their own experiences and benchmarks. Suggestions are made for potential optimizations, including using a different shell like zsh for potential performance gains, leveraging awk, and exploring alternative algorithms. The inherent limitations of Bash for this type of application are recognized, and the discussion explores the trade-offs between performance and the novelty of the implementation.
The practical applications of the project are also debated. While some view it primarily as a technical demonstration or a fun experiment, others suggest potential use cases where performance isn't critical. One commenter proposes using it for generating simple visualizations in constrained environments where other tools might not be available.
The choice of Bash itself is discussed. Some commenters question the rationale behind using Bash, suggesting more suitable languages for such a project. Others defend the choice, highlighting the value of exploring unconventional approaches and pushing the boundaries of what's possible with a familiar scripting language. The discussion touches upon the educational aspects of the project and its potential to inspire creative solutions.
Beyond the technical aspects, there's appreciation for the author's clear and well-documented code. The readability and organization of the project are commended, making it easier for others to understand and learn from the implementation. The project is also seen as a testament to the flexibility and power of Bash, even beyond its typical use cases. Some commenters express interest in exploring the code further and potentially contributing to its development.
The blog post "DOS APPEND" from the OS/2 Museum meticulously details the functionality and nuances of the APPEND command in various DOS versions, primarily focusing on its evolution and differences compared to the PATH command. APPEND, much like PATH, allows programs to access data files located in directories other than their current working directory. However, while PATH focuses on executable files, APPEND extends this capability to data files, specified by various file extensions.
The article begins by explaining the initial purpose of APPEND in DOS 3.3, highlighting its ability to search specified directories for data files when a program attempts to open a file not found in the current directory. This eliminates the need for programs to explicitly handle path information for data files. The post then traces the development of APPEND through later DOS versions, including DOS 3.31, where a significant bug related to networked drives was addressed.
A key distinction between APPEND and PATH is elaborated upon: PATH affects only the search for executable files (.COM, .EXE, and .BAT), while APPEND pertains to data files with extensions specified by the user. This difference is crucial for understanding their respective roles within the DOS environment.
The blog post further delves into the various ways APPEND can be used, outlining the command-line switches and their effects. These switches include /E, which loads the appended directories into an environment variable, /PATH:ON, which enables searching the appended directories even when a full path is provided for a file, and /PATH:OFF, which disables this behavior. The post also explains the use of /X, which extends the functionality of APPEND to affect the EXEC function calls, thus influencing child processes.
The evolution of APPEND continues to be discussed, noting the removal of the problematic /X:ON and /X:OFF switches in later versions due to their instability. The article also touches upon the differences in behavior between APPEND in MS-DOS/PC DOS and DR DOS, particularly concerning the handling of the ; delimiter in the APPEND list and the search order when multiple directories are specified.
Finally, the post concludes by briefly discussing the persistence of APPEND in later Windows versions for compatibility, even though its utility diminishes in these more advanced operating systems with their more sophisticated file management capabilities. The article thoroughly explores the intricacies and historical context of the APPEND command, offering a comprehensive understanding of its functionality and its place within the broader DOS ecosystem.
The Hacker News post titled "DOS APPEND" with the link https://www.os2museum.com/wp/dos-append/ has several comments discussing the utility of the APPEND command in DOS and OS/2, as well as its quirks and comparisons to other operating systems.
One commenter recalls using APPEND frequently and finding it incredibly useful, particularly for accessing data files located in different directories without having to constantly change directories or use full paths. They highlight the convenience it offered in a time before sophisticated development environments and integrated development environments (IDEs).
Another commenter draws a parallel between APPEND and the modern concept of environment variables like $PATH in Unix-like systems, which serve a similar purpose of specifying locations where the system should search for executables. They also touch on how APPEND differed slightly in OS/2, specifically regarding the handling of data files versus executables.
Further discussion revolves around the intricacies of APPEND's behavior. One comment explains how APPEND didn't just search the appended directories but actually made them appear as if they were part of the current directory, creating a virtualized directory structure. This led to some confusion and unexpected behavior in certain situations, especially with programs that relied on obtaining the current working directory.
One user recounts experiences with the complexities of managing multiple directories and files in early versions of Turbo Pascal, illustrating the context where a tool like APPEND would have been valuable. This comment also highlights the limited tooling available at the time, emphasizing the appeal of features like APPEND for streamlining development workflows.
Someone points out the potential for conflicts and unexpected results when using APPEND with programs that create files in the current directory. They suggest that APPEND's behavior could lead to files being inadvertently created in a directory different from the intended one, depending on how the program handled relative paths.
The security implications of APPEND are also addressed, with a comment mentioning the risks associated with accidentally executing programs from untrusted directories added to the APPEND path. This highlights the potential security vulnerabilities that could arise from misuse or improper configuration of the command.
Finally, there's a mention of a similar feature called apppath in the REXX language, further illustrating the cross-platform desire for this kind of directory management functionality.
Overall, the comments paint a picture of APPEND as a powerful but somewhat quirky tool that provided a valuable solution to directory management challenges in the DOS/OS/2 era, while also introducing potential pitfalls that required careful consideration. The discussion showcases how APPEND reflected the computing landscape of the time and how its functionality foreshadowed concepts that are commonplace in modern operating systems.
Summary of Comments ( 19 )
https://news.ycombinator.com/item?id=42749402
Hacker News users generally praised the Interactive systemd (ISD) project for its intuitive and user-friendly approach to managing systemd units. Several commenters highlighted the benefits of its visual representation and the ease with which it allows users to start, stop, and restart services, especially compared to the command-line interface. Some expressed interest in specific features like log viewing and real-time status updates. A few users questioned the necessity of a TUI for systemd management, suggesting existing tools like
systemctlare sufficient. Others raised concerns about potential security implications and the project's dependency on Python. Despite some reservations, the overall sentiment towards ISD was positive, with many acknowledging its potential as a valuable tool for both novice and experienced Linux users.The Hacker News post discussing the "Interactive systemd" project generated a moderate amount of discussion, mostly revolving around existing tools and alternative approaches to systemd management.
Several commenters pointed out existing tools that offered similar functionality, such as
systemctl status -l, which provides detailed status information for units. One user mentioned usingjournalctl -fu <unit>for following logs, suggesting the interactive systemd project might be over-engineered for simple use cases. This sentiment was echoed by another who found existing tools sufficient and preferred their terminal's copy-paste functionality.The discussion touched upon the perceived complexity of systemd itself. One commenter expressed their dislike for systemd, finding its structure unnecessarily complex and expressing a preference for simpler init systems like OpenRC and runit. Another user argued that while systemd is complex, this project doesn't address the underlying complexity; instead, it simply offers a different interface. They suggested that improving systemd's documentation might be a more effective approach.
Some commenters appreciated the visual representation offered by the interactive systemd tool, particularly for exploring relationships between units. One user praised the tool's potential for educational purposes, allowing users to visualize the systemd structure and understand the dependencies between various services. Another found value in the tool for navigating complex systems and quickly grasping the overall state of different units.
A few commenters focused on specific technical aspects. One inquired about the possibility of integrating the tool with other systemd management tools like Cockpit. Another raised the issue of handling large numbers of units and potential performance implications. The discussion also briefly touched on the use of Python and the psutil library, with one commenter mentioning an alternative Python library for systemd interaction.
Finally, the original poster (OP) engaged with several comments, answering questions about the project's motivation, technical implementation, and future plans. They clarified that the tool is intended to complement existing tools, not replace them, and highlighted its unique features such as the visualization of unit dependencies and interactive exploration. The OP also acknowledged the feedback regarding existing alternatives and expressed interest in exploring integration with other tools.