No, SQL Server is only available for Windows platforms. However, the SQL Server ODBC driver enables you to access SQL Server from applications running on Linux and UNIX platforms.
SQL Server uses a protocol called Tabular Data Stream (TDS) for communication between client applications and SQL Server. Because TDS can be used over TCP/IP, remote client applications can communicate with SQL Server. It is not therefore necessary for client applications and SQL Server to run on the same machine.
ODBC, which provides a standard way for applications to access databases, is one of the available client library APIs that can provide an interface to TDS. Microsoft has supported ODBC in all versions of SQL Server and has committed to continue to support ODBC in future versions of SQL Server. Microsoft’s SQL Server Native Client, which enables Windows client applications to access SQL Server, contains an ODBC driver.
If you want to use SQL Server, but do not have any Windows machines at your site, you can use SQL Azure instead. SQL Azure provides database functionality as a pay-as-you-go utility service and is built on SQL Server technologies. Because SQL Azure uses Tabular Data Stream (TDS), client applications can use the same tools and libraries to access SQL Azure Database as they do to access SQL Server. The SQL Azure ODBC driver enables you to access SQL Azure from Linux and UNIX platforms.