Question

In a linux command line

Give AWK commands for accomplishing each of the following: Print the 2nd last field (the field directly before the last field) of each line from a file named 'last.txt' Assume you have a file called 'names' that contains a list of people, one person per line. Also, assume that on each line the 3rd field on that line contains the age of the person. Some of the people do not have an age listed, and those lines only have 1 field. Print the total age for all the people that have an age (the sum of all of their ages). Print the total number of lines from a file named 'lines' Exchange the first and the third fields of every line, and then print the lines (you can print each line directly after the exchange). After printing all of the lines, print out the message "Done!". Assume the file name is 'switch txt'.

Answer 1

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Ans c)

Print the second last field of each line in the file:

awk -F '{print $(NF-1)}' lines

The sum of all ages:

awk 'if(length($3) > 0) {n += $3}; END{print n}' names

Total number of lines in the file:

In general, wc -l <filename> will give total number of lines in the file. If you want to do this using awk, use

awk '{print NR}' lines | tail -1

If you only want to use awk, do

awk 'BEGIN{i=0}{i++;}END{print i}' lines

swap first and third column:

awk -F, '{ print $3 "\\" $1 }' switch.txt

also can be done using sed command:

sed 's/^\(.*\),\(.*\)$/\3\\\1/g' switch.txt