Task 02 — Count unique IPv4 addresses

Write a script 02.sh that reads an access log and prints how many distinct client IPv4 addresses appear in the first field of each line.

Submit as

02.sh

Input

Source	Format
CLI	`./02.sh <access.log>` — path to a text log file
Log file	One request per line. First whitespace-separated field is the client IP (nginx/Apache combined log format). Example line:

192.168.1.1 - - [25/May/2026:09:00:01 +0000] "GET / HTTP/1.1" 200 612

| | Field 1 = 192.168.1.1. Blank lines, if any, should not break your script. |

Output

Stream	Format
stdout	Exactly one line: a non-negative integer (the unique IP count). No extra text, labels, or blank lines.
stderr	Not checked
Exit code	`0` on success

Example

Input file access.log:

192.168.1.1 - - [25/May/2026:09:00:01 +0000] "GET / HTTP/1.1" 200 612
10.0.0.5 - - [25/May/2026:09:00:02 +0000] "GET /api HTTP/1.1" 200 41
192.168.1.1 - - [25/May/2026:09:00:03 +0000] "GET / HTTP/1.1" 200 612
203.0.113.42 - - [25/May/2026:09:00:04 +0000] "POST /login HTTP/1.1" 302 0

stdout:

(Three unique IPs: 192.168.1.1, 10.0.0.5, 203.0.113.42.)

What the grader checks

Visible (4 pts) — public fixture log:

Exit code 0 (2 pt)
stdout is exactly 5 (2 pt). On failure: expected 5 vs got

Hidden (3 pts) — separate log you do not see. Pass/fail only.

Hints

awk '{print $1}' — first column only
sort -u then wc -l, or awk associative array