title: can't change the content of variable in file using sed
body: <p>I have a file that has the variable in it like this :</p>
  <p>destination=/usr/src/test</p>
  <p>I want with the sed command, change the content of the destination variable to become like this :
  destination=/etc/app</p>
  <p>for this i used : <strong><em>sed -i 's/destination=.</em>/destination=/etc/app/' nameoffile</strong>*</p>
  <p>but I had this mistake : sed: -e expression #1, char 29: unknown option to `s'</p>
  <p>any solution !!</p>