uuidgen

uuidgen is a command-line utility that generates Universally Unique Identifiers (UUIDs). It is distributed with many operating systems and software packages and is commonly used to create distinct identifiers for files, sessions, databases, and distributed systems.

A UUID is defined by RFC 4122 and is typically represented as 36 characters consisting of 32 hexadecimal digits separated by hyphens in the form 8-4-4-4-12. The most common output from uuidgen is a version 4 UUID, generated from random numbers; other versions (time-based v1, name-based v3/v5) exist, and some implementations allow selection of the version.

Usage and options: Running uuidgen prints a single UUID to standard output. Some implementations can generate multiple UUIDs in one invocation or support different formatting options; consult the local manual for precise capabilities and syntax.

Availability: On Linux and other Unix-like systems, uuidgen is usually provided by the uuid-runtime package or by util-linux’s libuuid. macOS includes it in the default toolset, and FreeBSD and other BSD variants provide it as part of their core utilities. Windows environments typically do not include a built-in uuidgen by default, but UUIDs can be obtained via the Windows API or through auxiliary tools and libraries.

See also: RFC 4122, Universally Unique Identifier, libuuid.