I've been programming for 20 years and apparently still don't understand what my terminal is doing. Recently I asked Claude Code to generate a small shell script. It came back full of escape codes and I just stared at it like a caveman looking at a smartphone. This article finally explains what's been happening right under my nose.
Also, disable the formatting if stdout is not a terminal. That way, your colors and cursor movements won't be visible when piping to another program, and your tool will be usable in apps that don't understand the CSI and chars that follow. Use a command-line switch with more than two states, e.g., `ls` (and probably other GNU tools) has `--color=always|auto|never` which covers most use cases.
Also not mentioned in the article: there are a few syntaxes available for specifying things in control sequences, like
\x1b[38;2;{r};{g};{b}m
for specifying colors. There's a nice list here: https://gist.github.com/ConnerWill/d4b6c776b509add763e17f9f1... You can also cram as many control codes as you want into a control sequence, though it probably isn't useful in a modern context in 99.9% of cases.
I've been programming for 20 years and apparently still don't understand what my terminal is doing. Recently I asked Claude Code to generate a small shell script. It came back full of escape codes and I just stared at it like a caveman looking at a smartphone. This article finally explains what's been happening right under my nose.
If you're going to do this also provide a way to disable it so parsers don't trip up on its escape-coded output.
Also, disable the formatting if stdout is not a terminal. That way, your colors and cursor movements won't be visible when piping to another program, and your tool will be usable in apps that don't understand the CSI and chars that follow. Use a command-line switch with more than two states, e.g., `ls` (and probably other GNU tools) has `--color=always|auto|never` which covers most use cases.
Also not mentioned in the article: there are a few syntaxes available for specifying things in control sequences, like
for specifying colors. There's a nice list here: https://gist.github.com/ConnerWill/d4b6c776b509add763e17f9f1... You can also cram as many control codes as you want into a control sequence, though it probably isn't useful in a modern context in 99.9% of cases.