<!-- GENERATED by docs/sphinx/bin/02-reference from POSIX.rs (xs_termios_setattr). Do not edit. -->

```{index} single: termios_setattr; POSIX function
```
```{index} single: POSIX::termios_setattr; Perl function
```

# termios_setattr

Apply the `POSIX::Termios` settings to `$fd`.

## Synopsis

```perl
use POSIX qw(TCSANOW TCSADRAIN);
$t->setattr(fileno(STDIN), TCSANOW);
```

## What you get back

`"0 but true"` on success, `undef` on failure. `$fd` defaults to
`0`, `$optional_actions` defaults to `TCSANOW` (apply immediately).

## Edge cases

- Negative `$optional_actions` sets `$!` to `EINVAL`.

## Differences from upstream

Fully compatible with upstream POSIX.