mifflin has asked for the wisdom of the Perl Monks concerning the following question:
I have a program that may try to get data from the command line using
However, there may not be any input. How do I detect if there is any input so the read will not block? Something like...while (<>) { }
UPDATE:if (data is available then) { while (<>) { } } else { # do something else }
Here is what I ended up doing get the behavior I was looking for...
Now, now matter how the user wants to give my prog the data like...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 $!;
or$ echo "text" | myprog
or$ myprog <<EOT some text EOT
I get text without blocking.$ myprog afile
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Replies are listed 'Best First'. | |
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Re: detect input available from command line
by Fletch (Bishop) on Mar 10, 2011 at 22:17 UTC | |
Re: detect input available from command line
by jwkrahn (Abbot) on Mar 10, 2011 at 21:33 UTC | |
by mifflin (Curate) on Mar 10, 2011 at 21:51 UTC | |
by Eliya (Vicar) on Mar 10, 2011 at 22:02 UTC | |
by jwkrahn (Abbot) on Mar 11, 2011 at 03:40 UTC | |
Re: detect input available from command line
by BioLion (Curate) on Mar 11, 2011 at 09:58 UTC | |
by mifflin (Curate) on Mar 11, 2011 at 16:49 UTC | |
by Anonymous Monk on Mar 11, 2011 at 17:13 UTC |
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