freetds

FreeTDS is a set of libraries for Unix and Linux that allows your programs to natively talk to Microsoft SQL Server and Sybase databases.

Query MSSQL with tsql command

TDSVER=7.0 tsql -H 192.168.1.123 -U userx -P 12345678 -p 1433

Show databases:

   1 select name from master..sysdatabases;
   2 go

Show tables:

   1 SELECT * FROM information_schema.tables;
   2 go