Re^2: <> oddity ?

As expected... hmm. Define a sample.txt like

1
2
3
[download]

And then run $ test.pl sample.txt

where test.pl is

#!/usr/bin/perl

use strict;
use warnings;

my $i = 0;
while (<>) {
    print $_;
    last if ++$i >= 2;
}

my $line;
print "My extra line: $line" while $line = <>;
[download]

Why would this program then NOT wait for any further input via STDIN ?

Comment on Re^2: <> oddity ? Select or Download Code

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Re^3: <> oddity ? by LanX (Cardinal) on Mar 27, 2013 at 11:50 UTC
> Why would this program then NOT wait for any further input via STDIN ? Perl can't read your mind, if you want to read from STDIN, explicitly use STDIN instead of stretching DWIM magic behavior till it breaks. UPDATE: actually your example is reading from STDIN, but maybe you should stop the redirecting from file to STDIN if you wanna read from interactive input (keyboard). see select Cheers Rolf ( addicted to the Perl Programming Language)	[reply]
Re^4: <> oddity ? by Krambambuli (Curate) on Mar 27, 2013 at 12:18 UTC
Just to clarify: wishing to deal with various use modes in a perfectly similar manner, I wanted to have 3 distinct modes of calling the program behaving absolutely similar, with minimum fuss about that in the code: $ test.pl sample.txt sample1.txt ... sampleN.txt $ test.pl <sample.txt $ cat sample.txt sample1.txt ... sampleN.txt \| test.pl All is well with this with the use of <>, except the fact that once EOF is seen, no further attempt to read from <> is allowed - or STDIN is opened, and will wait forever if you're unaware of it... Thanks you helping to sort this out. UPDATE As perlop says in 'I/O Operators': The <> symbol will return "undef" for end-of-file only once. If you call it again after this, it will assume you are processing another @ARGV list, and if you haven't set @ARGV, will read input from STDIN. Now I know :)	[reply]
Re^4: <> oddity ? by Krambambuli (Curate) on Mar 27, 2013 at 11:58 UTC
OK, got it solved and understood now, thanks. I actually just want NOT to read from STDIN when there is a file given in the command line, and stop reading when that file is exhausted. Turns out that I should NOT any further $line = <> once that hit EOF, because the immediate next attempt to do so will just open STDIN. Ahaa... :) Thank you.	[reply]


The stupid question is the question not asked
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Re^2: <> oddity ?

UPDATE: