I guess a little explanation is in order, about the assign command
uhm....as you know, from the very first day, the Amiga was designed to use diskettes, and to differentiate about which file was on which diskette, they didn't just use the df0: df1: and so on for the drive. They made it so you could type "cd mydisk:" in the shell, and you went to the disk called "mydisk" no matter what drive it was in.
Commodore (and the employers that designed the Amiga before Commodore bought it) then thought "Wouldn't it be cool if could make the computer believe this and that directory was a disk by itself?" So they invented Assign.
Which, effectively, can be used to "fool" the Amiga into thinking drive ENV: is inserted, when in reality it's a directory in RAM:
So that when you (in Shell) type "cd env:" you happened to end up in RAM:Env
Assign can of course be used to make any number of "disks" appear to be inserted.
disknames on the Amiga is not limited to A: B: C: ..... Z: like on some other "computer" we all love to dislike. A disk's name can be anything up to 30 (?) characters.
"A_Very_Long_Disk_Name" is a valid name for your diskette, actually. And.....what's more: insert the disk into any of you 4 available diskette drives, type "cd A_Very_Long_Disk_Name" and there you are. Put it into another one, and type the same....... Amiga Magic at it's peak :P