MacOS X terminal date and variable problem

I had this bat file in win that worked fine

set day=%date:~0,2%
set month=%date:~3,2%
set year=%date:~6,4%
set filename=hello-%anno%_%mese%_%giorno%开发者_如何学编程-world.txt
my-program.exe --report-file=%filename%

I've passed on MACOS X and I'm trying to have the same work using a *.commad file but I can not pass the date variable in the file name argument:

my-program --report-file= date "+%Y_%m_%d"

doesn't work! And I need to add the words 'Hello' and 'word.txt' in the filename!

Tried to use set and $1 but couldn't hang it over

set date "+%Y_%m_%d"
echo $1

echoes date

Any help will be appreciated!

---

In order to use the output of the date program, you need to use command substitution. You can do this either by surrounding it with backticks or parenthesis with a leading dollar sign.

my-program −-report-file=`date "%Y_%m_%d"`

or

my-program --report-file=$(date "%Y_%m_%d")