Built-in Variables
------------------

   `awk''s built-in variables are:

`ARGC'
     The number of command line arguments (not including options or the
     `awk' program itself).

`ARGIND'
     The index in `ARGV' of the current file being processed.  It is
     always true that `FILENAME == ARGV[ARGIND]'.

`ARGV'
     The array of command line arguments.  The array is indexed from 0
     to `ARGC' - 1.  Dynamically changing the contents of `ARGV' can
     control the files used for data.

`CONVFMT'
     The conversion format to use when converting numbers to strings.

`FIELDWIDTHS'
     A space separated list of numbers describing the fixed-width input
     data.

`ENVIRON'
     An array containing the values of the environment variables.  The
     array is indexed by variable name, each element being the value of
     that variable.  Thus, the environment variable `HOME' would be in
     `ENVIRON["HOME"]'.  Its value might be `/u/close'.

     Changing this array does not affect the environment seen by
     programs which `gawk' spawns via redirection or the `system'
     function.  (This may change in a future version of `gawk'.)

     Some operating systems do not have environment variables.  The
     array `ENVIRON' is empty when running on these systems.

`ERRNO'
     The system error message when an error occurs using `getline' or
     `close'.

`FILENAME'
     The name of the current input file.  If no files are specified on
     the command line, the value of `FILENAME' is `-'.

`FNR'
     The input record number in the current input file.

`FS'
     The input field separator, a blank by default.

`IGNORECASE'
     The case-sensitivity flag for regular expression operations.  If
     `IGNORECASE' has a nonzero value, then pattern matching in rules,
     field splitting with `FS', regular expression matching with `~'
     and `!~', and the `gsub', `index', `match', `split' and `sub'
     predefined functions all ignore case when doing regular expression
     operations.

`NF'
     The number of fields in the current input record.

`NR'
     The total number of input records seen so far.

`OFMT'
     The output format for numbers for the `print' statement, `"%.6g"'
     by default.

`OFS'
     The output field separator, a blank by default.

`ORS'
     The output record separator, by default a newline.

`RS'
     The input record separator, by default a newline.  `RS' is
     exceptional in that only the first character of its string value
     is used for separating records.  If `RS' is set to the null
     string, then records are separated by blank lines.  When `RS' is
     set to the null string, then the newline character always acts as
     a field separator, in addition to whatever value `FS' may have.

`RSTART'
     The index of the first character matched by `match'; 0 if no match.

`RLENGTH'
     The length of the string matched by `match'; -1 if no match.

`SUBSEP'
     The string used to separate multiple subscripts in array elements,
     by default `"\034"'.

   See Built-in Variables, for more information.