# types.RunOptions.separateStderr

- **Module:** types
- **Package:** libtmux
- **Language:** TypeScript
- **Kind:** property
- **Source:** https://github.com/libtmux/libtmux-ts/blob/ad09eaef7ffff40f510989ee0695852c44a31576/packages/libtmux/src/types.ts#L606
- **Page:** https://libtmux.org/en/ts/latest/reference/types-runoptions-separatestderr/

Send the program's stderr to a private file rather than the terminal, and return it as [`stderr`](/en/ts/latest/reference/errors-tmuxtransporterror-stderr-1umi/), so [`output`](/en/ts/latest/reference/program-program-output/) holds stdout alone. stderr is then no terminal, which some programs notice. Like [`input`](/en/ts/latest/reference/types-spawnoptions-input/), it needs the tmux server on this machine.