#Prefixed output

A single script and a serial group inherit the terminal, so their output is untouched. A parallel group of two or more members pipes them so each line can say which script wrote it.

[api] listening on http://localhost:4000
[web] vite v6.0.1  ready in 412 ms
[web] ➜ Local:   http://localhost:5173/
[api] GET /health 200 1.2 ms

#The prefix

The prefix is the member's script name in square brackets, followed by one space, in a colour that stays the same for the whole run. Names are not padded to a common width, so a line starts as soon as the bracket closes.

Six colours cycle in the order members are declared: cyan, magenta, green, yellow, blue, bright magenta. Red is left out, because a red prefix on an ordinary line reads as a failure the script never reported.

#A group of one is not prefixed

A group with exactly one member runs that member with the terminal inherited, exactly as a single script would. There is nothing to disambiguate, and prefixing it would silently degrade a config that happens to wrap one script in a group.

#Partial lines

Bytes are forwarded as they arrive, not held until a newline. A prompt that ends mid-line renders immediately rather than waiting for output that may never come.

When a different script writes while a line is still open, Rune injects a newline first, so two scripts never share a line. A carriage return re-emits the prefix, which keeps progress bars that redraw a single line readable.

Child bytes themselves are never rewritten. Whatever the tool emitted is what reaches the terminal, minus nothing.

#Colour through the pipe

A piped process sees a pipe rather than a terminal, and most tools turn colour off when they do. Rune detects colour support on its own output and forwards FORCE_COLOR to piped members, so tools that honour it keep their colour.

NO_COLOR set to any value turns off Rune's own colour, including prefixes.

A member with interactive: true is not piped at all. It inherits the terminal, so it is not prefixed and it detects colour for itself.

#Broken pipes

When Rune's own output goes to a pipe that closes, such as rune run dev | head -20, it stops writing, terminates the members, and exits. It does not keep running invisibly with nowhere to write.

#Encoding

Output is decoded incrementally, so a multi-byte character split across two reads is reassembled rather than corrupted. Bytes that are not valid UTF-8 pass through as they arrived.