System Programming in Perl

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Am I talking to a terminal device?

In Perl, the code might look something like this:

(If you love C)

        @statinfo = stat STDOUT;
        if (    $statinfo[2] & 0060000 == 0020000
            && ($statinfo[6] & 0xff) == 5) { say "Terminal" }
        else { say "Not a terminal" }

Or more likely, for portability reasons, you'd use isatty:

        use POSIX 'isatty';
        if (isatty(STDOUT)) { say "Terminal" } 
        else { say "Not a terminal" }

Or even more likely, you'd use Perl's built-in -t operator

        if (-t STDOUT) { say "Terminal" } 
        else { say "Not a terminal" }

Internally, -t just uses isatty

isatty itself is highly system-dependent

On my GNU/Linux system it uses ioctl

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