Mars729 writes "GUIs are walled gardens in that features available in one piece of software is not available to other pieces of software. However, there is software out there with command-line options that can make software features accessible to power users and programmers. Some important ones I have uncovered are:
- Exiftool: A command-line application that can read/write almost any kind of metadata contained in almost any filetype
- Imagemagick: This and similar software like GraphicsMagick is a full-feature toolkit for displaying, converting and editing image files.
- Irfanview: Like Imagemagick but faster, although it has much fewer features.
FFMpeg: For video files
- VLC: For audio and video files
- Aspell: A command line spell checker
- Google Static Maps API: A URL with coordinates, markers, zoom levels and other options to show a custom map from Google Maps. (I just uncovered this: no need to learn KML!)
Less useful but still useful are command shells. These provide file management mostly. I believe some of them may allow for sending and retrieving email messages. Also useful but less accessible and with a steeper learning curve are software with APIs and scripting. Examples would be Visual Basic for Applications in office software and groovy scripting for Freeplane. What else is out there?"