I am assuming that you have both the Linux site and the (old) Windows site using the same database, and I am also assuming that the Linux server is operating currently on a numeric IP only until the migration. If that is the case, you do not want to alter the database at all-- not until you are ready for a proper migration. To test the Linux server using the "live" database, add a couple of constants to the
wp-config.php file on the Linux server.
define( 'WP_SITEURL', 'http://xxx.xxx.xxx.xxx' );
define( 'WP_HOME', 'http://xxx.xxx.xxx.xxx' );
By doing that, the Linux server will operate somewhat independently of the Windows server, but without any database alterations.
This is really a "quick test" only solution. Be very careful who has access to the test server and be very careful what you do.
- "Static" resources like (most) images will still load from the
Windows server but that is probably acceptable for testing purposes.
- If you add/update posts on the Linux server you will probably have
to do a search and replace on the database after the migration, and may have oddball links on the Windows server during the transition. If you decide not to migrate you will likely have broken links. Be aware.
If you really want a thorough test, then lock out admin access on the Windows server to essentially freeze the database, copy the database for use with the Linux server, search and replace the copied database, and more or less migrate the site but use the IP address instead of the domain name.