Command:   tr - translate character codes
Syntax:    tr [-cds] [string1] [string2]
Flags:     -c  Complement the set of characters in string1
           -d  Delete all characters specified in string1
           -s  Squeeze  all  runs  of  characters  in  string1  to   one
               character
Examples:  tr '[A-Z]' '[a-z]' <x >y      # Convert upper case  to  lower
                                      case
           tr -d '0123456789' <f1 >f2   # Delete all digits from f1

     Tr  performs  simple  character  translation.   When  no  flag   is
specified,  each  character  in string1 is mapped onto the corresponding
character in string2.