And lo, the aspirant was directed to the holy documentation of the camel, in the perldoc of perlipc, wherein it is written:

Be careful to check both the open() and the close() return values. If 
+you're writing to a pipe, you should also trap SIGPIPE. Otherwise, th
+ink of what happens when you start up a pipe to a command that doesn'
+t exist: the open() will in all likelihood succeed (it only reflects 
+the fork()'s success), but then your output will fail--spectacularly.
+ Perl can't know whether the command worked because your command is a
+ctually running in a separate process whose exec() might have failed.
[download]

and also therein is described the fix, but that is left for the aspirant who now knows where to look to find the wisdom he seeks.

(HTH!)

I get the hint. :-) I'll try slogging my way through perlipc. I'll admit I looked at it ever so briefly but its big hairy title scared me away.

$PM = "Perl Monk's";
$MCF = "Most Clueless Friar Abbot Bishop";
$nysus = $PM . $MCF;
Click here if you love Perl Monks

Update: See the section on Pipes in chapter 6 of the camel for more information; reading up on the specifics of pipes on your OS might also provide enlightenment (they are strange beasts, and can cause all sorts of oddball errors if handled improperly).

Actually, the explanation behind this one is even simpler. You're opening a pipe to perl, with "non-existant_file" called as an argument. That pipe will succeed; perl will be opened, and subsequently exit, but the point is that the "open" call itself was successful -- you were able to open a handle to a perl process.

The cheap and easy way around this is to make sure that whatever you intend to open on a pipe is executable and has the shebang at the top, and omit the perl. e.g.:

#!/usr/bin/perl
use strict;
open (PIPE,"|non-existant_file") or die "Can't open pipe: $!";
print "hello";
sleep 5;
print "goodbye";
[download]

As an aside, it doesn't even have to be perl inside the pipe for this to be a factor. This could just as easily have been a pipe to awk or gzip or foobarbazwhee with incorrect arguments -- as long as the right-hand side of the pipe is, in fact, invoked, open doesn't fail.

Spud Zeppelin * spud@spudzeppelin.com