Have you tried -p STDIN?

Just tested -p and looks like that's just the opposite of -t. At least in my case that is the behavior.

I guess my question was more on the side of I didn't know what to search for. The -p and -t operators can accomplish what I need. It's almost silly that the solution was staring me in the face and I didn't know it. During my many searches, I came across -p a couple times and maybe -t, but didn't have the instinct to look them up.

Thanks again for the help.

ooh thanks BrowserUk never eard of -p operator, or may be forgotten it long time ago.
Due to my ignorance i wonder if -p -t are one the opposite of the other: in the docs -p is just mentioned and, albeit self explanatory, not described. There are cases where -t does not suffice, are also cases where -p does not suffice? edge cases?
My test:

perl -e " print -t STDIN ? qq(STDIN has tty) : qq(NO tty associated);p
+rint ' - '; print -p STDIN ? qq(STDIN is a pipe or a named pipe) : qq
+(NOT a pipe)"

#out
#STDIN has tty - NOT a pipe


hostname | perl -e " print -t STDIN ? qq(STDIN has tty) : qq(NO tty as
+sociated);print ' - '; print -p STDIN ? qq(STDIN is a pipe or a named
+ pipe) : qq(NOT a pipe)"

#out
#NO tty associated - STDIN is a pipe or anamed pipe
[download]

thanks
L*
There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

There are cases where -t does not suffice, are also cases where -p does not suffice? edge cases?

Search the stat() docs for S_IFIFO.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

#!/usr/bin/perl
use POSIX qw(isatty);
if (isatty(STDIN)) {
   die("nope. not like that\n");
}
while (<>) {
   print "$_\n";
}
[download]

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.

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.

IIRC, there is in fact a way to tell if STDIN is connected to a tty. It might be a *nix system call. In fact, I recall doing this myself many, many moons ago for basically the same reason you are. I'd have to do some searching myself, but look for how to determine if a process is connected to a terminal instead of how to determine if STDIN is from a pipe, that will probably get you closer to finding an answer.

I have a script that does something like that. It deals with text and can read that text from a file if $ARGV[ 0 ] is a readable file, from @ARGV if present but not a file, from a piped command if there's something to read on STDIN or typed in if not. It uses IO::Select to determine if input is waiting to be read on STDIN and thereby makes the assumption that it is being piped to.

use strict;
use warnings;

use IO::Select;

...

my $text;
if ( @ARGV )
{
    if ( -r $ARGV[ 0 ] )
    {
        $text = do {
           local $/;
           <>;
           };
    }
    else
    {
        $text = join q{ }, @ARGV;
    }
}
else
{
    my $select = IO::Select->new();
    $select->add( \ *STDIN );
    print
       qq{Type text, finish with ctrl-D on its own line\n}
       unless $select->can_read( 0.05 );

    $text = do {
       local $/;
       <>;
       };
}

...

# Do something with $text
[download]

I hope this is of use.

I am not answering your question because I wonder if you are asking the wrong question.

In your first case you need to learn to intervene gracefully.

You script is waiting for end of input, so tell it there is no more input.

In a UNIX shell ctrl-D indicates end of file.