SQLite Forum

No ".open" option in version 3.7.17 2013-05-20
The first several bytes in an sqlite db are ascii "SQLite format 3" (without the quotes). There are exceptions to that with some VFS implementations, but for those you'd have to do something special with sqlite3.exe anyway.

If you open the file with a binary editor, you can check for that string, or if you have unix utilities:

strings myfile.db | head

to see if that string shows up.