We introduced a new flag, --file (or -f for short). When --file is used, the following argument is always interpreted as a filename, i.e. the following are equivalent: 1. mongosh mongodb://localhost/ foo.js bar.js 2. mongosh mongodb://localhost/ --file foo.js --file bar.js This is relevant because the first argument can be either a filename or a connection string/database name/etc. Concretely: mongosh some.where → connects to mongodb://some.where/ and opens a shell mongosh some.js → connects to mongodb://localhost/ and runs some.js The reason for this is that mongosh treats the first positional argument as a file if and only if: 1. --nodb is passed, or 2. The first argument does not start with mongodb:// or mongodb+srv:// and ends in either .mongodb or .js. (This differs from the legacy shell in that .mongodb is new as a file extension here, and that the legacy shell also treated the first argument as a filename if it contained a dot after the first forward or backwards slash, which is a rule that mongosh does not honour.) With --file, this becomes unambiguous: mongosh -f some.where → connects to mongodb://localhost/ and runs some.where as a JS file mongosh -f some.js → connects to mongodb://localhost/ and runs some.js as a JS file Because this is unambiguous, we would generally prefer that the --file variant is used primarily in the docs, and that the mongosh <url> <files...> variant without --file is discouraged.