I'm on my way, I've seen the light and it's not a train at the other end of the tunnel

What tutorial or manual or reference point(s) would you recommend for an experienced DOS and CP/M type, who wants to learn the command equivalents within Unix?

I have a good understanding of program scripts, execution, directories, operations, etc. on those other operating systems, just need to bone up on the Unix command levels. Example: The old DOS command "attrib" (for read/write assignments) is similar to "chmod" command in unix.

Any ideas/input is welcome.

Thanks in advance.