Characters with special meaning for the shell

The characters

   ;  &  ( )  |  ^  <  >  ~  %  { }
   $  #   '  "  \  @@  *  ?  [ ]  -  !
   Newline (a <Return>)
   Space   (a <Space>)
   Tab	   (a <Tab>)

are all shell metacharacters. To the shell, they represent something other than the character or symbol that they are.

You must quote any command argument or regular expression containing one or more of these, so that it is passed to the command unchanged.