Using pipes

…Unix operating systems use the idea of a pipe to…connect the output of one program to the input of another.…Which let's you string together small, general…purpose tools to perform various tasks without programming.…For example, back in the movie about associative arrays, I showed you…an AWK program to count the occurrences of each word in its input.…It was a program called wordusage.awk.…We'll take our dukeofyork.txt input.…And you see it produces a count of the…number of times each word was found in the input.…

It comes out in arbitrary order because we…used the for in loop to produce the output.…If we wanted to sort this output alphabetically, we don't…have to go back and add code to the program.…Instead, you can just pipe the output of AWK, do…the sort command which sorts its output alphabetically by default.…Another very common pipe is to add the more…command to display the output one screenful at a time.…So, here we see the beginning of the alphabetical output, followed by a…prompt indicating to press the space bar to see the rest of it.…