vm2.UlidTool 1.0.9

UlidTool - ULID Generator Command Line Tool

• Installation
• Quick Start
• What is a ULID?
• Command Line Options
• Output Formats
  • Format Abbreviation
• Examples
• Related Packages
• License

A CLI tool for generating ULIDs (Universally Unique Lexicographically Sortable Identifiers). The tool is based on the vm2.Ulid library and provides various output formats and options for generating ULIDs from the command line.

Installation

dotnet tool install -g vm2.UlidTool

Quick Start

# Generate a single ULID
ulid

# Generate multiple (5) ULIDs
ulid -n 5

# Generate 3 ULIDs in GUID-like format
ulid -n 3 -f guid

# Generate a single ULID with detailed information
ulid -f detailed

What is a ULID?

ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier that combines:

• 48-bit timestamp (millisecond precision)
• 80-bit randomness

Benefits over traditional GUIDs/UUIDs:

• ✅ Lexicographically sortable by creation time
• ✅ Compact - 26 characters vs 36 for GUIDs
• ✅ URL-safe - Uses Crockford's Base32 encoding
• ✅ Monotonic - Within the same millisecond, values increment
• ✅ Compatible - Can be converted to/from GUID

Command Line Options

ulid [options]

Options:
  -n, --number <number>  Number of ULIDs to generate (1-10000) [default: 1]
  -f, --format <format>  Output format [default: ulid]
  -h, --help             Show help information
  --version              Show version information

Output Formats

1. ULID (default)

   26-character Crockford's Base32 string, lexicographically sortable:

   ulid
   # 01K5ETWXTDG0ZK9PP9WMC6V4HY
   

2. GUID-like

   36-character hexadecimal GUID-like format:

   ulid -f guid
   # 01934b8e-c6d9-7f40-9a99-f1c66d8c568e
   

3. Detailed

   Multi-line display showing the two main string formats and the two components - timestamp and random bytes:

   ulid -f detailed
   # ULID: 01K5ETWXTDG0ZK9PP9WMC6V4HY
   # GUID: 01934b8e-c6d9-7f40-9a99-f1c66d8c568e
   #   Timestamp:    01K5ETWXTD       2024-01-15T10:30:45.123+00:00 (1705315845123)
   #   Random Bytes: G0ZK9PP9WMC6V4HY [ 0x7F, 0x40, 0x9A, 0x99, 0xF1, 0xC6, 0x6D, 0x8C, 0x56, 0x8E ]
   

Format Abbreviation

The --format option accepts any unique prefix (case-insensitive):

• u, ul, uli, ulid → ULID format
• g, gu, gui, guid → GUID format
• d, de, det, ... detailed → Detailed format

Examples

1. Generate test data

   # Generate 100 ULIDs for database seeding
   ulid -n 100 > test-ids.txt
   

2. Create GUID-compatible IDs

   # Generate ULIDs in GUID format for legacy systems
   ulid -n 10 -f g
   

3. Inspect ULID structure

   # Examine the components of a ULID
   ulid -f d
   

Related Packages

• vm2.Ulid - ULID library for .NET applications
• ULID Specification - Official ULID spec

License

MIT - See LICENSE