How to setup db credentials for `sqlcmd` using a config file?
The odbc.ini for mssql doesn't support the user and password. 

Server parameter is used to specify port with syntax [protocol:]Server[,port]

Check /etc/odbcinst.ini for what driver name to use.

$ cat /etc/odbcinst.ini
[ODBC Driver 17 for SQL Server] # must match the 'Driver' in odbc.ini
Description=Microsoft ODBC Driver 17 for SQL Server
Driver=/opt/microsoft/msodbcsql17/lib64/libmsodbcsql-17.3.so.1.1
UsageCount=1

$ cat /etc/odbc.ini
[ExampleDataSourceName]
Driver=ODBC Driver 17 for SQL Server
Database=example_database_name
Server=tcp:10.1.2.3,50001

$ sqlcmd -D -S ExampleDataSourceName -U user