In weblogic 11g, the admin server port (default 7001) can be changed from the EM console. No restarts are necessary.
==> Correction: it may be necessary to restart the admin server. I have had cases where one did not need to, and cases where a restart had to be done.
After changing the admin server port, all managed servers can still be started from the console. Starting managed servers with the startManagedWebLogic.sh script fails however. This is caused by the definition of the admin server url in the startManagedWebLogic.sh script.Change it in the line: