'(WARN|ERROR)[ ]{1,}\[[\.a-z0-9A-Z]{1,}\]'
egrep '(WARN|ERROR)[ ]{1,}\[[\.a-z0-9A-Z]{1,}\]' -o server.log
To summarize, its necessary make uniq count the rows, to do that, its necessary sort them first (with the sort command). Finnaly sort it by total (with the -gr parameters) and get the top 10 with head (and the -n 10 parameter):
egrep '(WARN|ERROR)[ ]{1,}\[[\.a-z0-9A-Z]{1,}\]' -o server.log | sort | uniq -ic | sort -gr | head -n 10
| [root@jboss-server log]# egrep '(WARN|ERROR)[ ]{1,}\[[\.a-z0-9A-Z]{1,}\]' -o server.log | sort | uniq -ic | sort -gr | head -n 10 | |
| 19680 WARN [org.jboss.ws.metadata.wsdl.WSDLDefinitions] | |
| 16587 ERROR [STDERR] | |
| 15940 WARN [org.ajax4jsf.renderkit.AjaxRendererUtils] | |
| 14682 ERROR [br.com.foo.exception.ExceptionHandler] | |
| 14074 WARN [org.ajax4jsf.context.AjaxContext] | |
| 10274 WARN [com.arjuna.ats.jta.logging.loggerI18N] | |
| 9832 WARN [eu.medsea.mimeutil.MimeDetectorRegistry] | |
| 8683 WARN [br.cliente.site.ABC.business.dao.ParametroDAO] | |
| 1633 ERROR [org.jboss.seam.exception.Exceptions] | |
| 233 ERROR [br.com.super.package.actions.anexarDocumentos.AnexarDocumentos] |