Log Level Filter

#!/usr/bin/env bash
set -euo pipefail

wanted="${1:-INFO}"

logs=(
	"[INFO] server started"
	"[WARN] cache is almost full"
	"[ERROR] payment callback failed"
	"[INFO] request completed"
)

for line in "${logs[@]}"; do
	if [[ "$line" == "[$wanted]"* ]]; then
		printf '%s\n' "$line"
	fi
done