Linux awk Command: Work with Columns

Printing columns

awk numbers the columns $1, $2, $3 and so on. $0 is the whole line. By default columns are separated by spaces.

awk '{print $1}' access.log

Prints the first column of each line. In a web server log this is the visitor's IP address.

awk '{print $1, $7}' access.log

Prints the IP address and the page that was requested.

awk -F, '{print $1}' names.csv

Uses a comma as the separator (-F,) and prints the first column of a CSV file.

awk -F: '{print $1, $7}' /etc/passwd

Lists each user account and its login shell.

Filtering rows

awk '$9 == 404' access.log

Shows only requests that returned a 404 Not Found error.

awk 'NR > 1' names.csv

Skips the first line. NR is the line number.

awk 'length > 80' notes.txt

Shows lines longer than 80 characters.

Adding things up

awk -F, 'NR > 1 {total += $3} END {print total}' names.csv

Adds up the third column, skipping the heading row, and prints the total at the end.

awk -F, 'NR > 1 {sum[$2] += $3} END {for (c in sum) print c, sum[c]}' names.csv

Adds up the amounts for each city.

awk 'END {print NR}' access.log

Counts the lines in a file.

Using awk with other commands

df -h | awk 'NR > 1 && $5+0 > 80 {print $6, $5}'

Lists any disks that are more than 80% full.

Quick reference