here is the cut-and-paste from the manual on the -s (silent) option.
you may want to check out the manual that is referenced at the bottome of this post.

SILENT Option

-S[ILENT]

Suppresses all SQL*Plus information and prompt messages, including the command prompt, the echoing of commands, and the banner normally displayed when you start SQL*Plus. If you omit username or password, SQL*Plus prompts for them, but the prompts are not visible. Use SILENT to invoke SQL*Plus within another program so that the use of SQL*Plus is invisible to the user.

SILENT is a useful mode for creating reports for the web using the SQLPLUS -MARKUP command inside a CGI script or operating system script. The SQL*Plus banner and prompts are suppressed and do not appear in reports created using the SILENT option.

source : http://download-west.oracle.com/docs....htm#sthref754
SQL*Plus® User's Guide and Reference
Release 10.1
Part Number B12170-01
Oracle Corp.