```{index} single: tcflush; POSIX function ``` ```{index} single: POSIX::tcflush; Perl function ``` # tcflush Discard buffered input, output, or both on terminal `$fd`. ## Synopsis ```perl use POSIX qw(tcflush TCIFLUSH TCOFLUSH TCIOFLUSH); tcflush($fd, TCIOFLUSH); # drop pending input and output ``` ## What you get back `"0 but true"` on success, `undef` on failure. Negative `$queue_selector` sets `$!` to `EINVAL`. ## Differences from upstream Fully compatible with upstream POSIX.