Shell Programming and Scripting

Hi
I am trying to do the substitution using the 'sed' editor. In the line below
I am trying to substitute all instances of XXX by the value of the variable PX

sed 's/XXX/${PX}/g' ${TEMPLETE} > ${TEMPLETE}.${PX}

The problem is that 'sed' editor takes ${PX} literary (without retrieving the value) and does the substitution. Is there any way to do it using 'sed' ?
May be somebody knows another approach to this ? Thanks a lot for help
-A

The single quotes prevent the substitution of any shell variables in the sed script. Use double quotes instead.

Code:

sed "s/XXX/${PX}/g" ${TEMPLETE} > ${TEMPLETE}.${PX}

If PX contains any special characters (in particular, slash) you will need to escape or work around those somehow.

Also look into the correct spelling of "template". Furthermore, see UNIX Shell Quote

Thanks