use Log::Log4perl qw(:easy);

$conf = <<EOT;
log4perl.rootLogger = DEBUG, Log1
log4perl.appender.Log1 = Log::Log4perl::Appender::File
log4perl.appender.Log1.filename = /tmp/test.log
log4perl.appender.Log1.mode = append
log4perl.appender.Log1.layout = Log::Log4perl::Layout::SimpleLayout
log4perl.appender.Log1.Threshold = INFO

log4perl.logger = TRACE, Log2
log4perl.appender.Log2 = Log::Log4perl::Appender::ScreenColoredLevels
log4perl.appender.Log2.layout = Log::Log4perl::Layout::PatternLayout
log4perl.appender.Log2.layout.ConversionPattern = %m%n

log4perl.category = DEBUG, Buffer
log4perl.appender.Buffer = Log::Log4perl::Appender::Buffer
log4perl.appender.Buffer.appender = Log1
log4perl.appender.Buffer.trigger_level = ERROR
EOT

Log::Log4perl->init(\$conf);

TRACE("message #1 (screen only)");
INFO("message #2");
INFO("message #3");
sleep(10);
ERROR("message #4");
[download]

when i run this, i get on screen:

message #2
message #3
message #4
[download]

and in the file:

INFO - message #2
INFO - message #3
INFO - message #2
INFO - message #3
ERROR - message #4
ERROR - message #4
[download]

the first two lines of the log file appear at the same time like the ones on the screen. the first line (message #1) to the screen appender just disappears but in the log file message #2, #3 & #4 get doubled when the ERROR trigger got hit.

very odd behaviour. didn't match my expectations.

greetings

You appear to be attempting to log to multiple places, hence all the double ups (and probably the cause of stuff not appearing on screen as expected). Try this:

use strict;
use warnings;

use Log::Log4perl qw(:easy);

my $conf = <<EOT;
log4perl.rootLogger = DEBUG, Log1
log4perl.appender.Log1 = Log::Log4perl::Appender::File
log4perl.appender.Log1.filename = /tmp/test.log
log4perl.appender.Log1.mode = append
log4perl.appender.Log1.layout = Log::Log4perl::Layout::SimpleLayout
log4perl.appender.Log1.Threshold = INFO

log4perl.logger = TRACE, Log2
log4perl.appender.Log2 = Log::Log4perl::Appender::ScreenColoredLevels
log4perl.appender.Log2.layout = Log::Log4perl::Layout::PatternLayout
log4perl.appender.Log2.layout.ConversionPattern = %m%n

log4perl.category = TRACE, Buffer
log4perl.appender.Buffer = Log::Log4perl::Appender::Buffer
log4perl.appender.Buffer.appender = Log1
log4perl.appender.Buffer.trigger_level = ERROR
EOT

Log::Log4perl->init(\$conf);

TRACE("message #1 (screen only)");
INFO("message #2");
INFO("message #3");
sleep(10);
ERROR("message #4");
[download]

EDIT: You've set the buffer to intercept all messages and only allow DEBUG and higher through. Thats why your onscreen TRACE message disappears. Still looking into the doubling up thing.

Oh, and I've updated my source - This gets the screen to display correctly, but everything is still doubled in the file.

Change this line

log4perl.rootLogger = DEBUG, Log1

To this:

log4perl.rootLogger = DEBUG, Buffer

And... you can remove this line if you'd like the TRACE category to show up on STDOUT

log4perl.category = DEBUG, Buffer

Let us know if that matches your expectations? Although deep down I think you'll find you may have to write a custom composite function if you'd like to get a deeper level of customization..