io.stderr

from "io" import stderr

The process's standard error stream, already open as an io.file instance.

Notes

stderr is a separate stream from stdout; a tool that merges both into one log (as the reference tests do) only preserves their relative order because neither stream buffers, so every write lands as soon as it happens. stderr shares the process's handle rather than owning it, so close on it does nothing, the same as on stdout.

Example

from "io" import stdout, stderr

stdout.writestring("stdout line\n")
stderr.writestring("stderr line\n")   // a separate stream, merged into the same log by the shell

println(typeof stderr)                // "file": stderr is an io.file instance, not a special type

stdout line
stderr line
file

See also