Conf file issues

# This conf is for PISC logs.
input {
    beats {
        stdin {
            codec => multiline {
            pattern => "^\s"
            what => "previous"
            }
        }
        codec => multiline {
            pattern => "^%{TIMESTAMP_ISO8601}"
            negate => true
            what => "previous"
        }
    }
}
filter {
    date {
        match => ["message", "YYYY-MM-DD HH:MM:SS"]
        target => "@timestamp"
    }
    grok {
        match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{LOGLEVEL:loglevel} - %{IP:client}:%{POSINT:port} - %{HOSTNAME:host} - (?<log_type>[A-Za-z\s]{0,17})\n%{JAVACLASS:exception_type}: (?<stack_trace>[A-Za-z0-9\n\s.`(),:\\&]*)" }
    }
 }
output {
    elasticsearch {
    }
    stdout{
        codec => rubydebug
    }
}

When I try to do the configtest, I get:

The given configuration is invalid. Reason: Expected one of #, => at line 4, column 15 (byte 65) after
# This conf is for PISC logs.
input {
beats {
stdin {:level=>:fatal}

Can someone help me out?

Why you put stdin input plugin config inside beats input plugin config? It is not supported according to the documentation https://www.elastic.co/guide/en/logstash/current/plugins-inputs-beats.html

Is this what you are trying to do?

input {
     stdin {
            codec =&gt; multiline {
            pattern =&gt; "^\s"
            what =&gt; "previous"
            }
        }

    beats {       
        codec =&gt; multiline {
            pattern =&gt; "^%{TIMESTAMP_ISO8601}"
            negate =&gt; true
            what =&gt; "previous"
        }
    }
}