killport

It's ugly, it leaves you feeling guilty, and it's something you really shouldn't do. But it is sometimes necessary to kill a running process. This usually happens only after trying everything else. You've asked politely using the application's Quit option. You pressed colon and typed q. Even mashing Escape or Ctrl+C hasn't worked, while the process ID in top persists in sucking your compute and memory resources. This is where kill, or even kill -9, is your friend. Like a cold-blooded assassin, it will destroy a process and purge your system of its memory. But what happens when you don't know which process to kill, or don't know which process is responsible for the process in stasis. Like any good assassin, you then need to do a little reconnaissance.

The top command and its ilk are great at displaying which processes are stalled and which are using CPU and memory resources, and you can use commands such as lsof to list which processes are accessing which files and devices. But processes accessing the network or running as a server are harder to track down. These processes will use a port for communication, usually waiting on data to arrive or processing data as it passes through, and killing processes such as these is precisely why the aptly named killport was developed. At its simplest, you run killport with a single argument for the port number. For instance, killport 22 would kill the SSH daemon if you're running it with the default configuration. Similarly, you can include more than one port to request the massacre of an entire suite of processes, and you can specify the signal if you want to inflict extra torture before a brute force attack. It's simple but works brilliantly and is a much better option than trying to work out which processes are attached to which services through netstat.

Project Website

https://github.com/jkfran/killport

Killport helps you to stop services running on specific ports without having to learn the arcane ways of netstat.

3D viewer

F3D

Ever since computers could draw dots and connect lines between them, we've had 3D viewers. Even in the 1960s, computers could drive oscilloscopes and cathode ray tubes to show three-dimensional objects mapped into a two-dimensional plane. It's an obsession that stuck with computers through the space-station approach in the 1968 movie 2001: A Space Odyssey, in the video game Maze (aka Maze War) in the 1970s, and through the plethora of wireframe and filled polygons that filled out televisions in the 1980s before accelerated graphics made it trivial from the 1990s onwards. Now you can view things in 3D anywhere, from your phone, within a web browser, and in real 3D with a VR headset. But you're still stuck if you need a quick preview of a 3D object from the command line. With a few minutes to spare on a desktop, you could quickly drop a file into Blender, create a quick scene, and render this, but the brilliant F3D does a better job with the output and does this without any complicated UI interaction right from the command line.

F3D will load a whole host of 3D files, from VTK files from 1993 to scientific datasets and PTS point clouds generated by modern LIDAR with millions of points. Whatever the content, it's beautifully rendered into a separate desktop window where you also have considerable control over the output. Mouse and shift will rotate and slide the scene around in three dimensions, while hotkeys can enable anti-aliasing, tone mapping, color cycling, point sprite rendering, HDR and environment mapping, opacity, and volumetric rendering. These options can also be provided on the command line, and the ray tracing option requires special build options to have been enabled, but they all look wonderful, and you often find yourself downloading all kinds of 3D files just so you can explore them so conveniently.

Project Website

https://f3d.app

F3D not only loads static 3D objects, but it can also load and display glTF 3D animations.