Typing instead of clicking
A CLI (command line interface) is a way of operating a computer by typing instructions. Where a GUI gives you icons and buttons to click, a CLI has you type commands into an application called a terminal.
Rows of text on a dark background look forbidding, but the idea is simple. You are asking the computer for something — show me what is in this folder, run this tool — using a short agreed vocabulary.
Why it is still used
- The same operation repeats exactly, as many times as you want
- A sequence of steps can be saved as a script
- It works over a remote connection, on machines with no desktop
- Output is text, so it can be piped into other tools
Clicking is intuitive, but repeating the same sequence a hundred times is not. A CLI collapses that into one command or script. Developer tools ship with CLI versions for exactly this reproducibility.
Why it suits AI
Coding agents such as Codex and Claude Code inspect files, run programs, and execute tests through a CLI. Instructions and results are both text, which the model can read directly, making the loop of run, check the result, decide the next step straightforward to build.
Tools like gogcli expose services you would normally click through — Gmail, Google Calendar — as command line operations. The CLI has become an entry point not only for people but for letting AI operate a service.
Starting out safely
Some commands delete files in bulk. Do not paste an instruction you do not understand; confirm what it targets and what it changes first. Begin with read-only operations such as checking where you are and listing files.