Questions[rename](ubuntu)

I have two files in a folder on my Ubuntu 16.04:

a1.dat
b1.DAT

I want to rename b1.DAT to b1.dat so I would have following files as a result in the folder:

a1.dat
b1.dat

I tried (unsuccessfully):

$ rename *.DAT *.dat
Bareword "b1" not allowed while "strict subs" in use at (user-supplied code).
Bareword "DAT" not allowed while "strict subs" in use at (user-supplied code).

and

$ find . -iname "*.DAT" -exec rename DAT dat '{}' \;
Bareword "DAT" not allowed while "strict subs" in use at (user-supplied code).
Bareword "DAT" not allowed while "strict subs" in use at (user-supplied code).

Searching for this resulted in no meaningful solution...

I can use the following command successfully, and I'm quite confident with this command to make other combinations:

rename 's/\.htm/\.html/' *.htm

However I want to know more about it, especially about s in it. They say it is a Perl expression. I haven't learned Perl programming language, so I have no idea why there is such a 's/\.htm/\.html/' argument. Would you tell me what it is?? Thanks for reading.

my hard drive is located in /media/ronin_cunningham/408242E58242DED2 and I want to change the name 408242E58242DED2 to StorageDevice. How would I do this from the terminal?

Thanks.

Hi all i was asked to find the terminal command that will make a copy of a file lets call it program3.cpp and give to the copy the name homework6.cpp. After that you will have two files with different names, but identical contents.

I know how to copy the file but i cant figure out how to create a second identical file with a different name. All help is appreciated. Thanks!

I need to rename the following:

file_001_loremipsum.png
file_002_dolor.png
file_003_sit.png
file_004_amet.png
file_105_randomness.png

into

upl_loremipsum.png
upl_dolor.png
upl_sit.png
upl_amet.png
upl_randomness.png

How do I make it happen with just one simple line of terminal command?