How to derive current date and time and append at the end of each line that contains 'Hello'

Question

I have the following file party.txt that contains something like the following:

Hello Jacky
Hello Peter
Bye Johnson
Hello Willy
Bye Johnny
Hello Mar         


        

Answer 1

This solution should work with any awk:

awk '/Hello/ {cmd="(date +'%H:%M:%S')"; cmd | getline d; print d,$0; close(cmd)}' party.txt

The magic happens in close(cmd) statement. It forces awk to execute cmd each time, so, date would be actual one each time.

cmd | get line d reads output from cmd and saves it to d.