Shell Programming and Scripting

What's the difference between using [[]] and (()) ?

---------- Post updated at 04:31 AM ---------- Previous update was at 04:27 AM ----------

Not so, I have also coded equivalent scripts in csh as well that use bc instead. In addition I have a ksh directory containing ksh scripts that use the functionality of ksh. I might also have phyton ones too.

(()) are optimized for numeric operands. So, if you run the following:

Code:

x=1
[[ $x -eq 1 ]] && echo "true"

ksh will do 2 steps... first it will expand $x and get an expression like:

Code:

[[ 1 -eq 1 ]]

Then it will evaluate the expression.

If you use:

Code:

x=1
((x==1)) && echo "true"

ksh will simply evaluate the expression. At least that's my understanding... Also I personally find the code easier to read if numeric comparisons use (()) syntax.