Question

Let me elaborate.

Say I have perl program

(whch was shamelessly copied and edited from perl
http://perldoc.perl.org/perlfaq8.html#How-can-I-open-a-pipe-both-to-and-from-a-command%3f
)

 use IPC::Open3;

 use Symbol qw(gensym);   

 use IO::File;
 local *CATCHOUT = IO::File->new_tmpfile;
 local *CATCHERR = IO::File->new_tmpfile;

 my $pid = open3(gensym, ">&CATCHOUT", ">&CATCHERR", "ping -t localhost");

 #waitpid($pid, 0);   

seek $_, 0, 0 for \*CATCHOUT, \*CATCHERR;

 while( <CATCHOUT> ) {

print $_;
}

But the problem with the above program is it will to a sort of readtoEnd() of the STDOUT belonging to the program ping.exe in this case and allow it ti be read all at once.

But what I want to be able to do is to read the STDOUT as it is being written out to STDOUT.

if I remove waitforpid() then program exits immediately, so that doesn’t help either.

Is that Possible ? If so, can you please point me in the right direction.

Update:
Drats!!!! I missed the | symbol… which is essential for piping the output out of ping and into the perl script!!!

Answer 1

One of the strengths (or weaknesses) of perl is that there is more than one way to do things. This works:

perl -e 'open(F,"ping localhost|"); while(<F>) { s/ms/Milliseconds/; print $_; }'

Just put the s/ms/Milliseconds/ to show that the data is being read and changed
Not sure exactly what you have wrong with Open3