## 11.4. Built-in Variables

Version | Variable | Description
--- | --- | ---
`awk` | `FILENAME` | Current filename
| `FS` | Field separator (a space)
| `NF` | Number of fields in current record
| `NR` | Number of the current record
| `OFMT` | Output format for numbers (`"%.6g"`) and for conversion to string
| `OFS` | Output field separator (a space)
| `ORS` | Output record separator (a newline)
| `RS` | Record separator (a newline)
| `$0` | Entire input record
| `$``n` | nth field in current record; fields are separated by `FS`
`nawk` | `ARGC` | Number of arguments on command line
| `ARGV` | An array containing the command-line arguments, indexed from 0 to `ARGC - 1`
| `CONVFMT` | String conversion format for numbers (`"%.6g"`) (POSIX)
| `ENVIRON` | An associative array of environment variables
| `FNR` | Like `NR`, but relative to the current file
| `RLENGTH` | Length of the string matched by `match()` function
| `RSTART` | First position in the string matched by `match()` function
| `SUBSEP` | Separator character for array subscripts (`"\034"`)
`gawk` | `ARGIND` | Index in `ARGV` of current input file
| `ERRNO` | A string indicating the error when a redirection fails for `getline` or if `close()` fails
| `FIELDWIDTHS` | A space-separated list of field widths to use for splitting up the record, instead of `FS`
| `IGNORECASE` | When true, all regular expression matches, string comparisons, and calls to `index()` s ignore case
| `RT` | The text matched by `RS`, which can be a regular expression in `gawk`

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