Simon Willison’s Weblog

Tips on Adding JSON Output to Your CLI App (via) Kelly Brazil—also the author of jc, the neat CLI tool that converts the output of common Unix utilities such as dig into JSON—provides some useful do’s and don’ts for adding JSON output as an option to a command-line tool.

Kelly recommends defaulting to arrays of flat objects—or newline-delimited objects—and suggests including an “unbuffer” option for streaming tools that discourages the OS from buffering output that is being sent through a pipe. # 20th April 2024, 9:43 pm

Trogon (via) The latest project from the Textualize/Rich crew, Trogon provides a Python decorator—@tui—which, when applied to a Click CLI application, adds a new interactive TUI mode which introspects the available subcommands and their options and creates a full Text User Interface—with keyboard and mouse support—for assembling invocations of those various commands.

I just shipped sqlite-utils 3.32 with support for this—it uses an optional dependency, so you’ll need to run “sqlite-utils install trogon” and then “sqlite-utils tui” to try it out. # 21st May 2023, 9:39 pm

Seashells. This is a really useful tool for monitoring the status of a long-running CLI script on another device. You can run any command and pipe its output to “nc seashells.io 1337”—which will then return the URL to a temporary web page which you can view on another device (including a mobile phone) to see the constantly updating output of that command. # 8th May 2023, 5:20 pm

jc (via) This is such a great idea: jc is a CLI tool which knows how to convert the output of dozens of different classic Unix utilities to JSON, so you can more easily process it programmatically, pipe it through jq and suchlike. “pipx install jc” to install, then “dig example.com | jc --dig” to try it out. # 5th December 2021, 11:05 pm

Command Line Interface Guidelines (via) Aanand Prasad, Ben Firshman, Carl Tashian and Eva Parish provide the missing manual for designing CLI tools in 2020. Deeply researched and clearly presented—I picked up a bunch of useful tips and ideas from reading this, and I’m looking forward to applying them to my own CLI projects. # 4th December 2020, 8:44 pm

How to get Rich with Python (a terminal rendering library). Will McGugan introduces Rich, his new Python library for rendering content on the terminal. This is a very cool piece of software—out of the box it supports coloured text, emoji, tables, rendering Markdown, syntax highlighting code, rendering Python tracebacks, progress bars and more. “pip install rich” and then “python -m rich” to render a “test card” demo demonstrating the features of the library. # 4th May 2020, 11:27 pm

pup. This is a great idea: a command-line tool for parsing HTML on stdin using CSS selectors. It’s like jq but for HTML. Supports a sensible collection of selectors and has a number of output options for the selected nodes, including plain text and JSON. It also works as a simple pretty-printer for HTML. # 14th February 2020, 4:25 pm

ripgrep is faster than {grep, ag, git grep, ucg, pt, sift} (via) Andrew Gallant’s post from September 2016 introducing ripgrep, the command-line grep tool he wrote using Rust (on top of the Rust regular expression library also written by Andrew). ripgrep is a beautifully designed CLI interface and is crazy fast, and this post describes how it gets its performance in a huge amount of detail, right down to comparing the different algorithmic approaches used by other similar tools. I recently learned that ripgrep ships as part of VS Code, which is why VS Code’s search-across-project feature is so fast. In fact, if you dig around in the OS X package you can find the rg binary already installed on your mac: find /Applications/Visual* | grep bin/rg # 16th April 2019, 5:52 pm

From Microsoft: C# and CLI under the Community Promise. Microsoft’s assurance that it won’t “assert its Necessary Claims” against alternative (including open source) implementations of the ECMA C# and CLR specifications. The promise doesn’t cover implementations of .NET, WinForms etc- so the Mono team have announced they will be splitting their project in to two packages—a safe, ECMA based package and a package containing everything else. # 7th July 2009, 11:15 am