emctl start dbconsole失败问题的解决
1、为了启动em，使用命令emctl start dbconsole。

[oracle@localhost DBOracle]$ emctl start dbconsole
Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2009 Oracle Corporation.  All rights reserved.
https://localhost.localdomain:1158/em/console/aboutApplication
Starting Oracle Enterprise Manager 11g Database Control ............................................................................................. failed.
------------------------------
Logs are generated in directory /usr/oracle/DBOracle/app/localhost.localdomain_mwdb/sysman/log

2、启动失败，查看日志，没找到解决方案。

[oracle@localhost DBOracle]$ vi /usr/oracle/DBOracle/app/localhost.localdomain_mwdb/sysman/log

" ============================================================================
" Netrw Directory Listing                                        (netrw v125)
"   /usr/oracle/DBOracle/app/localhost.localdomain_mwdb/sysman/log
"   Sorted by      name
"   Sort sequence: [\/]$,\.h$,\.c$,\.cpp$,*,\.o$,\.obj$,\.info$,\.swp$,\.bak$,\~$
"   Quick Help: <F1>:help  -:go up dir  D:delete  R:rename  s:sort-by  x:exec
" ============================================================================
../
pafLogs/
.emagent_perl.trc
emagent.log
emagent.trc
emagent.trc.1
emagent.trc.2
emagent_perl.trc
emagentfetchlet.log
emagentfetchlet.trc
emctl.log
emctl.msg
emdb.nohup
emdctl.log
emdctl.trc
emoms.log
emoms.trc
emoms.trc.1
emoms.trc.2
nfsPatchPlug.log
patchAgtStPlugin.log
secure.log
                                                                        
3、直接输入emctl start得到相关命令的提示。     
                
[oracle@localhost DBOracle]$ emctl start
Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2009 Oracle Corporation.  All rights reserved.
   Oracle Enterprise Manager 10g Database Control commands:
        emctl start | stop dbconsole
        emctl status | secure | setpasswd dbconsole
        emctl config dbconsole -heap_size <size_value> -max_perm_size <size_value>
       emctl status agent
       emctl status agent -secure [-omsurl <http://<oms-hostname>:<oms-unsecure-port>/em/*>]
       emctl getversion
       emctl reload | upload | clearstate | getversion agent
       emctl reload agent dynamicproperties [<Target_name>:<Target_Type>]....
       emctl config agent <options>
       emctl config agent updateTZ
       emctl config agent getTZ
       emctl resetTZ agent