Shell Programming and Scripting

Hi, I'm trying to do something like this: range= `expr `date '+%m'` - 1` and it does not work. How can I tell it to evaluate an expression within another expression evaluation? I was at first worried that `date '+%m'` would return a string but apparently expr does the math okay normally, so the problem is how to get it to evaluate an inner set of backticks within the outer set of backticks. Thanks.

Jeriryan,
Sometimes, it is best to simplify -- it is better for future enhancements
and maintenance:

Code:

mm=`date +'%m'`
range=`expr $mm - 1`
echo "range = "$range

Personally, I agree with Shell_Life - but there is a way to do it.

backslash the inner back ticks - like this:
echo `expr \`date '+%m'\` - 1`
6

With bash and ksh you can use the syntax $(...), which accepts imbrication, instead of `...`

Code:

range=$(expr $(date '+%m') - 1)

or

Code:

(( range=$(date '+%m') - 1 ))