Color-Coded URL Status Checker in Bash: Enhanced Script for Fast Web Health Monitoring

Introduction: check-urls.sh – Fast, Visual URL Status Checks in Bash

Monitoring the health of multiple URLs is a common DevOps and web operations task. But staring at a wall of status codes can be tedious. What if you could instantly spot issues with color-coded output, all from a simple Bash script?

This post walks you through an improved Bash script that:

• Reads URLs from a file
• Checks their HTTP status using curl with a configurable timeout
• Outputs results as status_code url, color-coded for instant readability

Body: Building a Smarter, More Readable URL Checker

check-urls.sh: The Enhanced Script

Below is the script. It’s concise, robust, and easy to integrate into any workflow.

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#!/bin/bash

# check-urls.sh: Color-coded HTTP status checker for URLs in a file

set -o nounset

URL_FILE="${1:-/tmp/urls2}"
TIMEOUT="${2:-5}"   # Default timeout in seconds

if ! command -v curl >/dev/null 2>&1; then
    echo "Error: curl is not installed." >&2
    exit 1
fi

if [[ ! -f "$URL_FILE" ]]; then
    echo "Error: File '$URL_FILE' not found." >&2
    exit 1
fi

# Color codes for output
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
RED='\033[0;31m'
GRAY='\033[1;30m'
NC='\033[0m' # Reset

while IFS= read -r line; do
    # Skip empty lines and comments
    [[ -z "$line" || "$line" =~ ^# ]] && continue

    # Fetch HTTP status code with timeout
    code=$(curl --max-time "$TIMEOUT" -s -o /dev/null -w "%{http_code}" "$line")

    # Choose color by status code
    if [[ "$code" =~ ^2[0-9][0-9]$ ]]; then
        color="$GREEN"
    elif [[ "$code" =~ ^3[0-9][0-9]$ ]]; then
        color="$YELLOW"
    elif [[ "$code" =~ ^4[0-9][0-9]$ || "$code" =~ ^5[0-9][0-9]$ ]]; then
        color="$RED"
    else
        color="$GRAY"
    fi

    # Output: status_code url
    echo -e "${color}${code} ${line}${NC}"
done < "$URL_FILE"

check-urls.sh: Usage and Customization

• Input file: By default, the script reads from /tmp/urls2. You can specify another file as the first argument.
• Timeout: The second argument sets the curl timeout (default: 5 seconds).
• Output: Each line shows the HTTP status code (colored) followed by the URL.

Example

Suppose urls.txt contains:

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https://google.com
https://httpstat.us/404
https://httpstat.us/500
# This is a comment
https://httpstat.us/301

Run:

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./check-urls.sh urls.txt 3

You’ll see:

• Green for 2xx (OK)
• Yellow for 3xx (redirects)
• Red for 4xx/5xx (errors)
• Gray for anything unexpected or unreachable

check-urls.sh: Why Color Matters

Color-coding status codes makes it trivial to spot issues in large lists:

• Green (2xx): All good
• Yellow (3xx): Redirects, worth checking
• Red (4xx/5xx): Broken or server errors, needs attention
• Gray: Timeouts, malformed responses, or unknown codes

This approach is especially useful in CI/CD pipelines, monitoring scripts, or manual audits.

Conclusion: Takeaways and Next Steps

A color-coded URL status checker in Bash is a simple yet powerful tool for web monitoring and troubleshooting. By leveraging curl with timeouts and ANSI color codes, you get fast, readable feedback on the health of your endpoints.