AWK Built-in Variables

The following tables lists some important AWK builtin variables:

Variable	Description
ARGC, ARGV	command-line arguments
FILENAME	name of the file that awk is currently reading.
FNR	current record number in the current file, incremented on new records read
NF	number of fields in the current input record
NR	number of input records processed since the beginning of the program’s execution
RLENGTH	length of the substring matched by the AWK’s match function
RS	input record separator (default: newline)
OFS	output field separator (default: blank)
ORS	output record separator (default: newline)
OFMT	output format for numbers (default: %.6g)
ENVIRON	array of environment variables; subscripts are names.