Re: Perl Cascading Calls, Losing STDIN?

[bbfu]

in reply to Perl Cascading Calls, Losing STDIN?

I'm not entirely sure I know what you're asking. I've included some test code and output below to hopefully clarify.

[johnsca@cory johnsca]# cat tst.pl
#!/usr/bin/perl

my $run = $ARGV[0] + 1;

chomp(my $val = <STDIN>);

print "Test #$run: '$val'\n";

system('./tst.pl', $run) unless $run >= 3;
[johnsca@cory johnsca]# ./tst.pl
foo
Test #1: 'foo'
bar
Test #2: 'bar'
baz
Test #3: 'baz'
[johnsca@cory johnsca]# cat tst.inp
foo
bar
baz
quux
[johnsca@cory johnsca]# ./tst.pl < tst.inp
Test #1: 'foo'
Test #2: ''
Test #3: ''
[johnsca@cory johnsca]# cat tst.inp | ./tst.pl
Test #1: 'foo'
Test #2: ''
Test #3: ''

Basically, the issue I'm seeing is that the subprocesses read from STDIN normally as long as it was not redirected or piped in any way. This seems strange, and I don't really have any idea why it would be handled any differently. I don't know if it's a perl issue, a shell issue, or an OS issue.

I get the same behavior on the following perls:

• v5.8.2 built for cygwin-thread-multi-64int
• v5.8.4 built for i686-linux

I tried it under bash on both systems, and ash on linux.

Anyway, sorry I can't really give any answers but hopefully this will prompt someone a little more knowledgeable in this area than myself to chip in.

P.S. In the future, it is best to include code samples (the minimum required to duplicate the behavior) to demonstrate exactly what your problem is.