gistfile1.sh

## put this in the path called genconfig;

#!/bin/bash
tmpfile=$(mktemp)
erb -T - $1 > $tmpfile
echo $tmpfile

# now you can make erb logstash templates like so;

input {  file {
type => "syslog"
add_field => [ "offset", "<%= `echo -n $(date +%z)` -%>" ]
}}

# and invoke them like this;

$ grep "offset" $(genconfig test1.erb)
add_field => [ "offset", "+0000" ]

or...

$ java -jar logstash-monolith.jar agent -f $(genconfig myinputs.conf.erb) 

Or you could just use chef!