note kennethk You can detect the presence of waiting input using [doc://select], like: <c>use strict; use warnings; my $vector = ''; vec($vector,fileno(STDIN),1) = 1; if (select($vector,undef,undef,0.01)) { while (<>) { print; } }</c> <p>where I have set a 10 millisecond timeout. Might be easier and more portable though to simply pass the filename as argument, and [doc://open] it yourself. Like many other unix command line tools. 929359 929359