in reply to Pipe problems

Make sure B has autoflush turned on before the print for STDOUT... 
$| = 1;
print ...

[download]

Also, terminate the print with a '\n'. Though you haven't shown it, I'm assuming A reads back the line printed from B. (If not, B can hang on the print waiting for A to read it if B prints a large enough string, filling the pipe.) Update: From your code, it looks like A sends the '\n' to B so the comment about terminting the print may not apply.

Replies are listed 'Best First'.
Re^2: Pipe problems
by sgifford (Prior) on Aug 31, 2004 at 19:36 UTC
    Autoflush on the WRITE filehandle in A seems more likely to be the problem. In newer versions of Perl you can use: 
    use IO::Handle;
# ...
WRITE->autoflush(1);

    [download]
    In older versions you should use: 
    $oldfh = select(WRITE);
$| = 1;
select($oldfh);

    [download]

    Update: bluto's right, IPC::Open2 does this for you. I usually just use pipe, which doesn't.

[reply]
[d/l]
[select]
      This won't help this problem. According to even older perl docs for IPC::Open2 autoflush is turned on for the parent's write handle.
[reply]

In Section Seekers of Perl Wisdom