Proven on a throwaway server: as the administrator a caller's $(SQLCMDPASSWORD) returned
the sa password, and a line beginning ':!!' ran a program in the tools container. The
statement now runs as mesh_mssql_reader (CONNECT ANY DATABASE, SELECT ALL USER SECURABLES),
with substitution off (-x), after the module's own text on the first line, and a line break
is refused. go-sqlcmd v1.10.0 is installed at a pinned digest: the image never had sqlcmd,
so every mssql tool failed with spawn sqlcmd ENOENT.