A CGI script to manage a logbook for Gemini protocol servers, written in GNU AWK. It enables users to retrieve and display logbook entries from a text file based on a date specified in the URL. Think of it as a lightweight tool for serving date-specific logbook content over the Gemini protocol.

Features

• Date-Based Retrieval: Extracts a date from the URL's PATH_INFO (e.g., /YYYY-MM-DD) to fetch the corresponding logbook entry.
• Input Validation: Ensures the date is in YYYY-MM-DD format.
• Gemini Protocol Compliance: Outputs proper Gemini response headers and formats content in the Gemini text format.
• Entry Display: Shows the title and full content of the logbook entry matching the requested date.
• Fallback Behavior: If no entry matches the date, displays a list of all available logbook entries with clickable Gemini links.
• Link Generation: Automatically creates Gemini links for each logbook entry, enhancing navigation.
• Atom feed: atom.xml script creates an automated Atom feed for your logbook.

Logbook File Format

The script expects a logbook file in the following format:

#### YYYY-MM-DD Title
Entry content line 1
Entry content line 2

#### YYYY-MM-DD Another Title
Another entry content

Each entry begins with a line starting with #### , followed by the date in YYYY-MM-DD format, a space, and the entry's title.

The entry's content follows on subsequent lines until the next #### line or the end of the file.

It fetches the date, title and content of each entry, creating its own gemlog page.

How It Works

1) Date Extraction and Validation:

• Grabs the first 10 characters of PATH_INFO after the leading / (e.g., 2023-10-15 from /2023-10-15). PATH_INFO is an environment variable given by the server. Check your server's documentation (YMMV).
• Validates the date format and range; if invalid, redirects to /cgi-bin/logbook with a Gemini redirect response.

2) Logbook Processing:

• Reads the logbook file line by line.
• Collects all entry titles for potential listing.
• When an entry’s date matches the request, outputs a Gemini success header (20 text/gemini), a capsule header with a home link, the entry’s title as a level 3 heading (###), and its content.

3) No-Entry Fallback:

• If no match is found after processing the file, sends a success header and displays a message indicating no entry exists for the date.
• Lists all logbook entries with their dates and titles as Gemini links (e.g., => /YYYY-MM-DD Title).

Requirements

• GAWK, of course.
• Gemini server with CGI support. It must offer the URL info given after the script (check PATH_INFO variable).

Setup Instructions

1. Place the Script: Copy the script to your Gemini server’s CGI directory (e.g., /var/gemini/cgi-bin/).
2. Set the Logbook Path: Edit the script to include the absolute path to your logbook file.
3. Make Executable: Run chmod +x script to grant execute permissions.
4. Access It: Visit gemini://yourcapsule.com/cgi-bin/script/YYYY-MM-DD in a Gemini client, replacing YYYY-MM-DD with the desired date.

Security Note

As a CGI script, ensure it doesn’t expose security risks. This script only reads a predefined file and avoids executing user input, but always review CGI deployments for potential vulnerabilities.