perlfilehandle

What is the -t used for in this Perl code

I read in the perldoc that the -t file operator is used to decide if a filehandle is opened to a tty or not. Then i read what a tty was and from what i understand it's an old term for a terminal?

My main question however is what this code is used for: 

if(-t STDERR) {
    die "some warning/error message here"
}

I guess i don't really understand what it means for a "filehandle to be opened to a tty". Does that mean that the particular output for that filehandle appears on the tty - or the terminal? Can tty refer to something besides the terminal?

Solution

  • This code wants to assert that standard error is being redirected to a file. So running

    perl the_script.pl

    would trigger the die call, but

    perl the_script.pl 2> error.log

    would not.