Lab: Deploy a Sharded Cluster || mongos.conf

shard1:PRIMARY> mongos -f mongos.conf
2021-07-11T19:17:21.509+0000 E QUERY [js] SyntaxError: missing ; before statement @(shell):1:10
mongos

Reason for syntax error is you are running the mongos command at mongo prompt
Exit and run from os prompt.It will work