gawk: Single Character Fields

 
 4.5.3 Making Each Character a Separate Field
 --------------------------------------------
 
 There are times when you may want to examine each character of a record
 separately.  This can be done in 'gawk' by simply assigning the null
 string ('""') to 'FS'.  (c.e.)  In this case, each individual character
 in the record becomes a separate field.  For example:
 
      $ echo a b | gawk 'BEGIN { FS = "" }
      >                  {
      >                      for (i = 1; i <= NF; i = i + 1)
      >                          print "Field", i, "is", $i
      >                  }'
      -| Field 1 is a
      -| Field 2 is
      -| Field 3 is b
 
    Traditionally, the behavior of 'FS' equal to '""' was not defined.
 In this case, most versions of Unix 'awk' simply treat the entire record
 as only having one field.  (d.c.)  In compatibility mode (See
 Options), if 'FS' is the null string, then 'gawk' also behaves this
 way.