Re: Syncing perltie filehandle STDOUT STDERR and system call

[jandrew]

I'm not sure I follow what you are trying to do in the big picture here so I have to ask if you have read the documentation for open. There is a section specifically dealing with redirecting STDOUT and STDERR. However, if after that review you still need some additional performance then you should investigate a really cool module from tobyink++ called IO::Callback that may fit your requirements.

Here is a Synopsis from him

[karthikm897]

Thanks jandrew, I haven't tried with IO::Callback, with which I think I need not use tiefilehandle anyway. But yes for your question , I already tried using "open" in pipe mode, this is not going to help me with its syntax limitation as I have a different subroutine for stdout & stderr and I can't open a pipe for both at same time. though indiviual pipe did help me redirect to the tied module function call back.

[jandrew]

karthikm897 you are correct that you don't need to tie the file handle with IO::Callback. The trick there is to use the select command. On the other hand for STDERR there is a fair amount going on in the background with perl so I would reccomend either looking at the perl documentation for sigtrap or working with the special %SIG variable to target specific error message types rather than redirecting STDERR wholesale.

[karthikm897]

Hi jandrew, I tried with IO::Callback, this din't work again. try this code

use IO::Callback;

# Here's the coderef
my $code = sub {
    my $str = shift;
    print STDERR "This is really bad: $str";
};

# Turn it into a filehandle opened in write mode
my $fh = IO::Callback->new('>', $code);

# Select that filehandle (makes it the default for print, say, etc). 
select($fh);

# Print something - it gets passed to the coderef!
print "Hello World\n";
system("date");

date output doesn't get default error meta text. Also this has been mentioned in Bugs section I already have a large number of pre-written scripts and trying to capture print STDERR from them, not the system generated error signals alone. So I would like to perform similar callback function for STDERR as well. Thanks