In Oracle11g the alert log is an XML file. The old style alertSID.log is created out of the log.xml for backward compatibility only. However, some exciting enhancement are not noticable in the old one.
$ tail -3 alert*.log
Mon Feb 04 15:52:38 2008
ALTER SYSTEM SET recyclebin='OFF' SCOPE=SPFILE;
ALTER SYSTEM SET recyclebin='ON' SCOPE=SPFILE;
If I check in the xml file, I get more info about the execution time, which contains milliseconds
$ adrci exec="show alert -term"|tail -4
2008-02-04 15:52:38.366000 +01:00
ALTER SYSTEM SET recyclebin='OFF' SCOPE=SPFILE;
2008-02-04 15:52:42.101000 +01:00
ALTER SYSTEM SET recyclebin='ON' SCOPE=SPFILE;
This timestamp could be really usefull !
There is also a command -tail for adrci, but it outputed the whole log for some unkown reason