Command Substitution:

This is a shell technique for grabbing the output of 
one command and using it in another command.

Suppose this command produces the date stamp we are after: 

              /bin/date -R|tr -d ','|awk '{print $1,$2,$3}'

and we want to put that datestamp string into another variable.

Start out with this structure:  

             $(  )
and          $(     )
just         $(         )
sneak        $(             )
up           $(                 )
quietly      $(                    )
on           $(                       )
the          $(                          )
command      $(                             )
and          $(                                )
enclose      $(                                   )
it           $(                                      )
with         $(                                         )
the          $(                                            )
brackets     $(/bin/date -R|tr -d ','|awk '{print $1,$2,$3}')


voila!   day=$(/bin/date -R|tr -d ','|awk '{print $1,$2,$3}' )