Replace two characters using one sed command
echo "A=[A]" | sed s'/[]=]/ /g'
A [A
You can use the '-e' flag to execute multiple substitutes, for example:
# echo "A = [A]" | sed -e 's/=//' -e 's/]//'
A [A
It might be possible to match both '=' and ']' in a single substitute but even if it is, I don't think it'll provide much benefit over using '-e'.
It's probably easier to use tr to do something like this as it doesn't involve messing with REs
echo "A=[A]<-" | tr "]=" " "
A [A <-