Learning AWK Programming

Using getline to output into a pipe

In this method, the output of a shell command can be piped into the getline using "command" | getline, which can be further used to generate output. The following examples illustrate how this method works:

$ vi getline_pipe.awkBEGIN   {        "date" | getline        print "Date is : ", $0         close("date")        print "====================="        print "DISK FREE SPACE INFO"        print "====================="        # using loop to print multiple lines        while (("df -h" | getline) > 0 )                print "Disk info : ", $0        close("df -h")}$ awk -f getline_pipe.awk 

The output of the execution of the preceding code is as follows:

Date is : Wed Mar 7 00:13:17 IST 2018=====================DISK FREE SPACE INFO=====================Disk info : Filesystem Size Used ...