[skydhash]

Red/green is semantic in these cases. They’re user configurable in almost all terminals, so there’s no real accessibility issue. I tend to associate blue with decorative accent, yellow with info/warning text, and cyan and magenta for really fancy stuff.

[tczMUFlmoNk]

Red/green has no inherent semantics. It has the semantics that you assign it. If you choose to assign it meaning that disenfranchises 8% of men using your system, that's your choice, but it is not a good one.

[skydhash]

Cultural semantics (diff tools, build tools,…: green/addition/ok, red/removal/error). And people with color blindness can alter the colors to something they can differentiate. And in the ansi sequences, they are actually numbers.

[mrob]

The standard terminal palette is only 16 colors. Even if you compress them all into the green-to-blue color range, it's still possible to distinguish all 16. The user can change "red" and "green" to whatever they like in the terminal preferences and then every 16-color app will be accessible with no additional effort from anybody.