POSIX Timezone Database Generator

A simple Python tool that generates POSIX timezone strings from system timezone data.

Overview

This tool reads binary timezone files from /usr/share/zoneinfo/ and extracts POSIX timezone strings, outputting them in either CSV or JSON format. It covers 469 timezone identifiers including all major regions worldwide.

Usage

# Generate CSV output
python gen-tz.py --csv

# Generate JSON output
python gen-tz.py --json

# Save to files
python gen-tz.py --csv > zones.csv
python gen-tz.py --json > zones.json

Output Format

CSV Format

"America/New_York","EST5EDT,M3.2.0,M11.1.0"
"Europe/London","GMT0BST,M3.5.0/1,M10.5.0"
"Asia/Tokyo","JST-9"

JSON Format

{
  "America/New_York": "EST5EDT,M3.2.0,M11.1.0",
  "Europe/London": "GMT0BST,M3.5.0/1,M10.5.0",
  "Asia/Tokyo": "JST-9"
}

POSIX Timezone String Format

The POSIX strings encode timezone rules including:

• Standard time abbreviation and UTC offset
• Daylight saving time rules (if applicable)
• DST transition dates using the format M<month>.<week>.<day>

Examples:

• GMT0 - Greenwich Mean Time, no DST
• EST5EDT,M3.2.0,M11.1.0 - Eastern Time with DST transitions
• JST-9 - Japan Standard Time, UTC+9, no DST

Requirements

• Python 3 (standard library only)
• System timezone data (/usr/share/zoneinfo/)
• No external dependencies

License

MIT License - See LICENSE file for details