Scenario: "Bologna": counting ELB 5xx errors

Level: Easy

Type: Do

Tags: bash  

Access: Email

Description: Operations handed you a classic AWS Elastic Load Balancer access log at /home/admin/elb.log. Each line is one request. Fields are space-separated; the quoted HTTP request starts at field 12, so the numeric fields before it are fixed-width columns.

Field 8 is the ELB status code and field 9 is the backend status code returned by the target instance. Count how many log lines have a backend status code in the 5xx range (500 through 599). Write that integer — digits only — to /home/admin/solution.txt. For example: echo 42 > ~/solution.txt

The log mixes successful responses, redirects, client errors, and server errors; only backend 5xx responses count toward your answer.

Root (sudo) Access: True

Test: The MD5 checksum of your answer file md5sum /home/admin/solution.txt is b73ce398c39f506af761d2277d853a92 (we also accept the correct count with a trailing newline in the file).

The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can see and execute.

Time to Solve: 15 minutes.