CLI Toolbox

ffmpeg

Convert a mkv file to mp4 (source).

ffmpeg -i "vid.mkv" -map 0 -c copy -c:a aac "MP4/vid.mp4"

entr

Use entr to execute a command every time a file is modified. For example, to watch the changes on a PDF file with a Markdown source while you edit it.

echo input_file.md | entr pandoc input_file.md -o output_file.pdf