Not every task requires a graphical user interface. Often it is quicker and more efficient to simply type a command. Command line tools allow you to perform powerful operations with just a few keystrokes and make it possible to automate repetitive tasks. Below is a selection of tools that I find particularly useful. All of them are free and open-source.

ImageMagick

ImageMagick can convert and resize images.

magick input_image.jpg -resize 300x output_image.webp

we can convert a SVG to a png

magick -background none -size 64x64 input.svg output.png

or combine multiple png files to create a .ico file

magick icon_small.png icon_medium.png icon_large.png icon.ico

ExifTool

The metadata is ExifTool can be used to modify the metadata of an image.

exiftool image.jpg

But we are more interested to remove it

exiftool -all:all= -r -overwrite_original image.jpg

FFmpeg

FFmpeg can be used to convert audio and video files.

ffmpeg -i input.mp3 -vn -acodec copy -ss 00:00:10 -to 00:00:30 output.mp3

wget

This will download the entire website (including css files).

wget -mkE www.example.com