in reply to How do I Determine if my script is being piped to?

You can tell if STDIN is a tty or not, which isn't quite the same thing, but it might suffice: 
#!/usr/bin/perl
use POSIX qw(isatty);
if (isatty(STDIN)) {
   die("nope. not like that\n");
}
while (<>) {
   print "$_\n";
}

[download]

Replies are listed 'Best First'.
Re^2: How do I Determine if my script is being piped to?
by netguy (Novice) on Nov 21, 2013 at 00:42 UTC

    Thanks much for the reply. I didn't expect an answer so fast or that it would provide the solution.

    Though the example you gave doesn't work, maybe because of 'use strict;' , I did find a couple things that do work. If I did have a better understanding of Linux, I may have found the answer on my own. Just something I'll have to work on.

    Here are a couple examples of what did work for me:
    use strict;

if ( -t STDIN ) {
    print "This is what you're supposed to do ...\n";
    exit;
}

# or 

use POSIX qw(isatty);
if ( isatty(\*STDIN) ) {
    print "This is what you're supposed to do ...\n";
    exit;
}

while (<STDIN>) {
    print STDOUT "Add something to STDOUT".$_;
}

    [download]

    Thanks for the help. It wasn't a show-stopping feature, just trying to mitigate confusion by some users when the command is run and the cursor just sits there doing nothing.
[reply]
[d/l]
Re^2: How do I Determine if my script is being piped to?
by boftx (Deacon) on Nov 21, 2013 at 00:16 UTC

    Well, kschwab has a much better memory that I do. You can pretty much ignore what I was posting at the same time he was giving you the answer I was looking for. :)

    It helps to remember that the primary goal is to drain the swamp even when you are hip-deep in alligators.
[reply]

In Section Seekers of Perl Wisdom