[iamtherockstar]

Huh? Since when do you always use 'ls' after 'cd' - I can think of many times that I don't need to do this, and it would annoy me if every time I called 'cd' it then printed out the directory listing as well.

The popular Unix mantra is "do one thing and do it well" - both these commands, while definitely connected, are each "one thing" and they both perform them very well.

[jiyinyiyong]

The philosophy of Unix convinced me at my first glance. But then found there might be some problem in this case.

Just an example. People may say something offer three features, one plus one and plus one, just like Unix does. But if we are going to explain 99, it is faster to say 100 minus 1 rather than 90 plus 9.

`cd $1 && ls` is a larger command. It's also an easier one.