logstash event modifiers

00-config

input {
  stdin {
    type => "test"
  }
}

filter {
  mutate {
    add_field => [
                  "regexp_test", "%{@message:s/foo/bar}",
                  "regexp_test_g", "%{@message:s/foo/bar/g}",
                  "tr_test", "%{@message:tr/./_/}"
                 ]
  }
}

output {
  stdout {
    debug => true
  }
}

01-sample_event

{
         "@source" => "stdin://carrera.databits.net/",
           "@type" => "test",
           "@tags" => [],
         "@fields" => {
          "regexp_test" => [
            [0] "bar.foo.foo"
        ],
        "regexp_test_g" => [
            [0] "bar.bar.bar"
        ],
              "tr_test" => [
            [0] "foo_foo_foo"
        ]
    },
      "@timestamp" => "2012-01-08T00:20:24.450000Z",
    "@source_host" => "carrera.databits.net",
    "@source_path" => "/",
        "@message" => "foo.foo.foo"
}