I've got a list of devices which I need to remove duplicates (keep only the first occurrence) while preserving order and matching a condition. In this case I'm looking for a specific string and then printing the field with the device name. Here is some example raw data from the sar application:
10:02:01 AM sdc 0.70 0.00 8.13 11.62 0.00 1.29 0.86 0.06
10:02:01 AM sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:02:01 AM sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Average: sdc 1.31 3.73 99.44 78.46 0.02 17.92 0.92 0.12
Average: sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Average: sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:05:01 AM sdc 2.70 0.00 39.92 14.79 0.02 5.95 0.31 0.08
10:05:01 AM sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:05:01 AM sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:06:01 AM sdc 0.83 0.00 10.00 12.00 0.00 0.78 0.56 0.05
11:04:01 AM sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
11:04:01 AM sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Average: sdc 0.70 2.55 8.62 15.91 0.00 1.31 0.78 0.05
Average: sda 0.12 0.95 0.00 7.99 0.00 0.60 0.60 0.01
Average: sdb 0.22 1.78 0.00 8.31 0.00 0.54 0.52 0.01
The following will give me the list of devices from lines containing the word "average" but it sorts the output:
sar -dp | awk '/Average/ {devices[$2]} END {for (device in devices) {print device}}'
sda
sdb
sdc
The following gives me exactly what I want (command from here):
sar -dp | awk '/Average/ {print $2}' | awk '!devices[$0]++'
sdc
sda
sdb
Maybe I'm missing something painfully obvious but I can't figure out how to do the same in one awk command, that is without piping the output of the first awk into the second awk.