getline

getline [var] [<file]
        or
command | getline [var]

Read next line of input. Original awk does not support the syntax to open multiple input streams. The first form reads input from file and the second form reads the output of command. Both forms read one line at a time, and each time the statement is executed it gets the next line of input. The line of input is assigned to $0 and it is parsed into fields, setting NF, NR and FNR. If var is specified, the result is assigned to var and the $0 is not changed. Thus, if the result is assigned to a variable, the current line does not change. It is actually a function and it returns 1 if it reads a record successfully, 0 if end-of-line is encountered, and -1 if for some reason it is otherwise unsuccessful. {N}