Why Start SQL*Plus with /nolog

Question

What is the difference between starting SQL*Plus as in
sqlplus sys as sysdba
versus
sqlplus /nolog
connect sys as sysdba
I can imagine that the second method prevents some log file from being written but sometimes logs are useful. Is there more to it than that?
Thanks,
Gregory

Answer 1

It's really interesting to see how a question like this gets answered. Some of what you've been told is true, some not, and most of it is a red herring...
First, using /nolog (as has been correctly stated) has nothing to do with logging. It means "start sqlplus but don't log on to any database just yet"
Second, its user or lack of has nothing to do with connecting as sys, as sysdba, or any other special connection. It means, simply and only, "start sqlplus but don't log on to any database just yet"
It has nothing to do with the ability to run a sql script.
It has nothing to do with your ability to supply a password.
One reason to use it in a *nix environment is to be able to hide the userid and/or password from someone querying processes.  As was hinted at, if someone performs a 'ps -ef', they will see the full command line that started the processes.  So, if you start with
$>sqlplus system/manager
a ps -f will show the username and password.
If you start with
$>sqlplus system
you will be prompted for password and ps -ef will show the username, because it was on the command line
If you start with
$>sqlplus /nolog
Then supply the username and pswd manually (or in a script), then ps -ef will only show that sqlplus is running, but will not reveal anything about the credentials used.