The specific customizations you can make may vary depending on the operating system and the SQL*Plus version. Generally, though, you need to be aware of the login scripts and the environment variable settings.
Two SQL scripts are executed whenever SQL*Plus starts up:
Site profile
The first script, known as the site profile, is named glogin.sql . It applies globally to all users on a particular computer.
User profile
The second script, known as the user profile (not the same thing as the product user profile discussed in Chapter 13), is named login.sql . Each user may have his or her own user profile script.
The most obvious use for these files is to execute SET commands to customize the environment settings to something other than their defaults.
Several operating system environment variables affect how SQL*Plus operates. Some of what these environment variables allow you to specify include:
SQLPATH
The search path to use for SQL scripts
LOCAL or TWO_TASK
A default database connection
NLS_LANG
The language being used
Under Windows, these settings can be made in the registry, but environment variables take precedence over their corresponding registry settings.