Variables are not processed for : commands

[shueybubbles]

this does not work:

sqlcmd -v file=select100.sql
1> :r $(file)
Sqlcmd: Error:  Error occurred while opening or operating on file $(file) (Reason: open $(file): The system cannot find the file specified.).

[shueybubbles]

Commands to fix:
:r, :!!, :exit, :connect