I have a program that may try to get data from the command line using
while (<>) {
}
However, there may not be any input. How do I detect if there is any input so the read will not block? Something like...
if (data is available then) {
while (<>) {
}
}
else {
# do something else
}
UPDATE:
Here is what I ended up doing get the behavior I was looking for...
my $stdin = IO::Select->new(\*STDIN);
open my $fh, '|-', $cmd or die $!;
if (@ARGV || $stdin->can_read(0)) {
while (<>) {
print {$fh} $_ or die $!;
}
}
else {
print {$fh} "\n" or die $!;
}
close $fh or die $!;
Now, now matter how the user wants to give my prog the data like...
$ echo "text" | myprog
or
$ myprog <<EOT
some text
EOT
or
$ myprog afile
I get text without blocking.