Tag: Cli

The POSIX diff, cmp and patch commands are very versatile. Sometimes, you need to edit a part of a file and send only your changes to somebody else to apply. This is where these handy commands can help. This post describes concisely how to use them to compare files, create patches and apply them.

Edit (2023-04-05): Added some suggestions by the author/developer of libvips.

Today I discovered libvips, a command line utility and library to manipulate and process images, and I am impressed. I’ve been using ImageMagick and its fork, GraphicsMagick, for as long as I have had to process images from the CLI, and they work well for moderately-sized images. But lately, I have been preparing virtual texture datasets for Gaia Sky and the sizes of my images have increased exponentially. Right now I’m processing 64K and 128K images on the regular (that is 131072x65536 pixels), and ImageMagick just can’t do it reliably. It uses so much memory that it can’t even split a 64K image in a 32 GB RAM machine without running out of it. Running it with the suggested options to limit memory usage (--limit memory xx mb, etc.) and use a disk cache never works for me. It just produces blank images for some reason. So after implementing a couple of Python scripts based on OpenCV and NumPy to do some basic cropping, I took on the task of finding a proper, capable replacement. And found it I did. Libvips is the perfect tool, it seems. Based on my few first tests, it performs much better than ImageMagick and GraphicsMagick. It is super fast and never seems to use much memory, no matter how big an image I throw at it.

GNU screen is a terminal multiplexer that allows for different virtual windows and panes running different processes within the same terminal session, being it local or remote. This post contains a quick reference to the most used default key bindings of GNU screen. In contrast to other terminal multiplexers like tmux, GNU screen is probably already installed in your server of choice.

If you usually develop your software without an IDE, it may come in handy to be able to run a custom command or two whenever a file or a group of files in the file system is modified. This post discusses entr, a small event notify test runner which might just be what you need to fill an inconvenient gap in your mouseless development environment.