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From: PerlFAQ Server on 30 Mar 2010 12:00
This is an excerpt from the latest version perlfaq8.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

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8.37: How do I find out if I'm running interactively or not?

Good question. Sometimes "-t STDIN" and "-t STDOUT" can give clues,
sometimes not.

if (-t STDIN && -t STDOUT) {
print "Now what? ";
}

On POSIX systems, you can test whether your own process group matches
the current process group of your controlling terminal as follows:

use POSIX qw/getpgrp tcgetpgrp/;

# Some POSIX systems, such as Linux, can be
# without a /dev/tty at boot time.
if (!open(TTY, "/dev/tty")) {
print "no tty\n";
} else {
$tpgrp = tcgetpgrp(fileno(*TTY));
$pgrp = getpgrp();
if ($tpgrp == $pgrp) {
print "foreground\n";
} else {
print "background\n";
}
}



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are not necessarily experts in every domain where Perl might show up,
so please include as much information as possible and relevant in any
corrections. The perlfaq-workers also don't have access to every
operating system or platform, so please include relevant details for
corrections to examples that do not work on particular platforms.
Working code is greatly appreciated.

If you'd like to help maintain the perlfaq, see the details in
perlfaq.pod.
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