Perl Capture and Modify STDERR before it prints to a file
- by MicrobicTiger
I have a perl script which performs multiple external commands and prints the outputs from STDERR and STDOUT to a logfile along with a series of my own print statements to act as documentation on the process.
My problem is that the STDERR repeats ~identical prints as example below. I'd like to capture this before it prints and replace with the final result for each of the commands i run.
blocks evaluated : 0
blocks evaluated : 10000
blocks evaluated : 20000
blocks evaluated : 30000
...
blocks evaluated : 3420000
blocks evaluated : 3428776
Here's how I'm getting STDOUT and STDERR
my $logfile = "Logfile.log"; #log file name
#--- Open log file for append if specified ---
if ( $logfile )
{
open ( OLDOUT, ">&", STDOUT ) or die "ERROR: Can't backup STDOUT location.\n";
close STDOUT;
open ( STDOUT, ">", $logfile ) or die "ERROR: Logfile [$logfile] cannot be opened.\n";
}
if ( $logfile )
{
open ( OLDERR, ">&", STDERR ) or die "ERROR: Can't backup STDERR location.\n";
close STDERR;
open ( STDERR, '>&STDOUT' ) or die "ERROR: failed to pass STDERR to STDOUT.\n";
}
and closing them
close STDERR;
open ( STDERR, ">&", OLDERR ) or die "ERROR: Can't fix that first thing you broke!\n";
close STDOUT;
open ( STDOUT, ">&", OLDOUT ) or die "ERROR: Can't fix that other thing you broke!\n";
How do I access the STDERR when each print is occurring to do the replace? Or prevent it from printing if it isn't the last of the batch.
Many Thanks in advance.
