AWK keyword
ARGCnumber of command-line arguments ARGVarray of command-line arguments FILENAMEname of current input file FNRrecord number in current file FSinput field separator (default= space and tab characters) NFnumber of fields in input line NRnumber of input lines read so far OFMToutput format for numbers (default=%.6) OFSoutput field separator (default=space) ORSoutput line separator (default=newline)..