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Postings from March 2000
First, notice:
% perl -we 'print scalar <STDOUT>'
Filehandle main::STDOUT opened only for output at -e line 1.
Strange. Readline forgot to return undef.
Now, watch this:
% perl -we 'open(OUT, "|cat"); print scalar <OUT>;close OUT'
Hold on. There's no output, which is expected. But there are
neither warnings for reading from a writeonly handle. And readline
still doesn't report the failed read.
What started me down this was an even worse problem:
open(BOTH_CAT, "|cat -un|") or die "no both cat: $!";
select ((select(BOTH_CAT), $| = 1)[0]);
print BOTH_CAT "stuff\n";
print "Want stuff: ";
print scalar <BOTH_CAT>;
print BOTH_CAT "more stuff\n";
print "Want more stuff: ";
print scalar <BOTH_CAT>;
close BOTH_CAT;
print "Done.\n";
When run, you get:
% perl -w ~/dubpipe
Can't open bidirectional pipe at /home/tchrist/dubpipe line 1.
1 stuff
2 more stuff
Want stuff: Want more stuff: Done.
Um, hello? It complains and then goes and does it anyway, but only
half-way? Why is this even *bothering* to fork and exec!? And
then once it does, it only gives me half yet doesn't mutter a peep
when I make use of the other half. You'd think that if it were
going to trouble itself to fork and exec, it would do the Right
Thing, but if--as I was expecting--it weren't going to do the Right
Thing, then it wouldn't bother to fork and exec in the first place.
This is not the classic behavior.
--tom
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