Very recently, I was present in a foreign language classroom where French was taught. I happened to be using the room as a workspace; I was not a student.
At the end of the lesson, I heard the teacher, who was probably not a native speaker, tell students to get in line in preparation for the transition to their next lesson by saying « En ligne ! ». This did not seem right to me. Firstly, my understanding is that « file » should be used rather than « ligne » when we are describing something like a queue; if I had to improvise and ask the students to be in line, I would have perhaps said « À la file ! ». Secondly, « en ligne » obviously means "on the internet" in common usage.
Was this French teacher's word choice correct at all? As I've explained, her word choice does not seem right to me, but given her profession, I would normally assume that she knows what she's saying.