Redirection

Redirection

Arrows move data left to right. They select streams independently of the typed pipeline operator.

Operator	Stream
->	Standard output
~->	Standard error
~+->	Both output streams

A variable target receives captured text. A quoted or interpolated path target is a file destination. Capture preserves bytes representable as UTF-8, including trailing newlines; trimming is explicit.

let $message: String
let $status = printf 'parcel\n' -> $message
echo $message.count $status
echo $message.trim

7 ExecResult(0)
parcel

Files and process input

A String value on the left of a file-reading arrow names a source file. A value piped into an external program supplies process input. Use a pipe when passing variable contents rather than reading a filename.

printf '%s' "cargo list" -> "manifest.txt"
let $contents: String
"manifest.txt" -> $contents
echo $contents

cargo list

Redirection is scoped to the command: later output returns to the usual stream. Keep execution status separate from captured text. For binary data, use Bytes and I/O; String capture is not a binary container. For bounded child execution with separate files and environment, use Process supervision.

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Related: Pipelines · Bytes and I/O · Process supervision