Counting with awk

Beyond printing fields, awk can calculate. You can use variables, patterns, and special blocks like END to produce summaries.

Summing a column

awk '{sum += $2} END {print sum}' readings.txt

This adds up every value in column 2 and prints the total after all lines are processed. The END block runs once, after the last line.

Counting lines that match a pattern

awk '/error/ {count++} END {print count}' log.txt

The /error/ is a pattern: only lines containing "error" trigger the action. At the end, we print how many matched.

Combining pattern and calculation

awk '$3 > 100 {print $1, $3}' data.txt

This prints field 1 and 3 only for lines where field 3 is greater than 100. Awk patterns can be regex (/word/) or conditions ($2 == "alpha").

Mission: Cargo Weight Report

The station is approaching a gravity-assist manoeuvre and the pilot needs a full cargo mass report. The file cargo_weight.txt lists each item and its weight in column 2.

1. Add up every weight in column 2 and print the combined total.
2. Save that total into a new file called total-weight.txt.
3. List only the heavy items (those with a weight above 100), showing the name and the weight.
4. Create a folder called flight-deck and move total-weight.txt into it.

Expected result

flight-deck/total-weight.txt holds the combined weight of all cargo items (610).