Grep in logstash

Hi

I am using grep in conf . while i am doing the test am getting the following error
[lee@server1 logstash-1.5.0]$ bin/logstash -f test4.conf --configtest
The error reported is:
Couldn't find any filter plugin named 'grep'. Are you sure this is correct? Trying to load the grep filter plugin resulted in this error: no such file to load -- logstash/filters/grep
I search in sites and found that installing contrib plugin will fix this . When i tried that am getting errors as well
[lee@server1 logstash-1.5.0]$ bin/plugin install contrib
Validating contrib
Plugin contrib does not exist
ERROR: Installation aborted, verification failed for contrib

could anyone please help me on this how to resolve.

Thanks in Advance

Regards
Lee

Don't use the obsolete grep filter; use conditionals instead, e.g. like this to delete all messages where the foo field isn't equal to "bar":

if [foo] != "bar" {
  drop { }
}