[gnufx]

If you want to simplify things, don't employ "useless us of cat". Pass the file as a command arg or re-direct input. And sort has options, so the third/fourth commands can be

sort -u -t, sales.csv

However, those fail with quoted commas.

Also, head -3 is non-POSIX obsolete syntax.

Edit: I don't know why I didn't see other UUOC references initially.