Regarding Compute reduce command

Dear all,
I am trying to compute the stresses generated on a specific group of atoms (say, Group1) in an NVT ensemble during the heating process.
I am looking for the average stress in the specified group, so I use the compute ave command. I am facing a problem with how to output this. Let’s say, the command reads,
compute cg1 Group1 reduce ave c_c_str_s[1]
Does this cg1 represent a scalar value, which is the average stress in the x direction for that specific group in the units of pressure*volume?
If yes, how can I output it? I tried equating c_cg1 using a variable command, but that did not help.
Please suggest if this representation is legitimate to compute the average stress in a specific group and, a way to retrieve this quantity.