CODEWITHSUNDEEP
bashawk
ustun
ustun

Reputation: 7021

Looping in bash for preparing awk's input statement

I am trying to parse some nginx logs by date. I have written an awk oneliner to find all matching logs for a day, like:

awk '/05\/May\/2012/ { print $0;}' /var/log/nginx/access.log

What I want to do is to loop over some days and months using bash. Here is what I have got

#!/bin/bash

for h in 2012
do
    for i in Apr May
    do
        for j in 01 02 03 04 05
        do
            echo "/${j}\/${i}\/${h}/"
            search_string="'/${j}\/${i}\/${h}/ { print \$0;}'"
            echo $search_string;
            awk $search_string /var/log/nginx/access.log  
            echo "${h} ${i} ${j} done" 
        done
    done
done

However, this fails on awk line with:

 awk: 1: unexpected character '''

It seems like I need to escape some variables, but I haven't found a solution so far.

Upvotes: 0

Views: 222

Answers (3)

Dennis Williamson
Dennis Williamson

Reputation: 359895

Here is your entire script in one AWK script:

awk 'BEGIN {
         years = "2012"
         months = "Apr|May"
         days = "01|02|03|04|05"
     }
     $0 ~ days "/" months "/" years {
         print
     }' /var/log/nginx/access.log

If you need the start and done markers, those can be added.

Upvotes: 3

dogbane
dogbane

Reputation: 274532

It's better to use awk's variable assignment feature to pass the shell variable into awk. Then use ~ to match the pattern. For example:

search_string="$j/$i/$h"
awk -v pattern="${search_string}" '$0 ~ pattern {print $0}' /var/log/nginx/access.log

This is the recommended method specified in the awk manual.

Upvotes: 6

kev
kev

Reputation: 161614

Single quotes are not needed. Double quotes are needed.

search_string="/${j}\/${i}\/${h}/ { print \$0;}"
awk "$search_string" /var/log/nginx/access.log

Upvotes: 2

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