HOW TO CREATE A PIPE - FIFO FROM SYSLOG-NG TO SPLUNK:

FIFO - First In First Out
mkfifo man page http://linux.die.net/man/3/mkfifo
mkfifo creates a special file- a named pipe, entered into the file system 
which needs to be opened on one end to read and another to write.

Note that I haven't used this method yet, but this is how I would do it:

su
1. Create the pipe:
mkfifo /var/log/syslog-ng_splunk


2. Add the pipe to syslog-ng:
pico /etc/syslog-ng/syslog-ng.conf
Paste in at the bottom:
# Pipe to splunk
source remote {
      udp();
    };

    destination splunk {
      pipe("/var/log/syslog-ng_splunk");
    };

    log {
      source(remote);
      destination(splunk);
    };

# Log host sending to syslog-ng
destination hosts {
      file("/var/log/hosts/$HOST/messages"
      owner(root) group(adm) perm(0640) dir_perm(0750) create_dirs(yes));
    };
    
    log {
      source(remote);
      destination(hosts);
    };


3. Add the pipe to Splunk:
cat /opt/splunk/etc/system/local/README
ls -al /opt/splunk/etc/system/README/inputs.*
  -r--r--r-- 1 splunk splunk  5418 2010-07-15 06:10 inputs.conf.example
  -r--r--r-- 1 splunk splunk 20569 2010-07-15 06:10 inputs.conf.spec

pico /opt/splunk/etc/system/README/inputs.conf.spec
Search for (Ctrl +w): fifo
Has this:
#*******
# FIFO:
#*******

[fifo://<path>]
* This directs Splunk to read from a FIFO at the specified path.

Change to:
#*******
# FIFO:
#*******

[fifo:///var/log/syslog-ng_splunk]
sourcetype = syslog
* This directs Splunk to read from a FIFO at the specified path.

(no need to chmod file)

4. Restart splunk and syslog-ng:
/opt/splunk/bin/splunk restart
/etc/init.d/syslog-ng restart


Settings for per hosts logs: http://mysfitt.net/tutorials/splunk1_fifo.php#configure-syslog
    destination hosts {
      file("/var/log/hosts/$HOST/messages"
      owner(root) group(logs) perm(0640) dir_perm(0750) create_dirs(yes));
    };
    
    log {
      source(remote);
      destination(hosts);
    };


Settings for Windows syslog-ng.conf: http://www.splunk.com/wiki/Deploy:CreateSyslogNGRules