as: o

 
 2.12 Name the Object File: '-o'
 ===============================
 
 There is always one object file output when you run 'as'.  By default it
 has the name 'a.out'.  You use this option (which takes exactly one
 filename) to give the object file a different name.
 
    Whatever the object file is called, 'as' overwrites any existing file
 of the same name.