It is not uncommon to come across open positions that actually do require Unix (not Linux) experience.
For example, American Express has a large deployment of AIX systems and they indeed look for candidates with experience in AIX systems, although I believe someone with experience in another Unix or Unix-like system should also be okay.
But I agree that such openings are usually quite specific about which Unix system they are working with.
For example, American Express has a large deployment of AIX systems and they indeed look for candidates with experience in AIX systems, although I believe someone with experience in another Unix or Unix-like system should also be okay.
But I agree that such openings are usually quite specific about which Unix system they are working with.