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Cmdliner — Declarative definition of command line interfaces for OCaml


Cmdliner allows the declarative definition of command line interfaces for OCaml.

It provides a simple and compositional mechanism to convert command line arguments to OCaml values and pass them to your functions. The module automatically handles syntax errors, help messages and UNIX man page generation. It supports programs with single or multiple commands and respects most of the POSIX and GNU conventions.

Cmdliner has no dependencies and is distributed under the ISC license.

Home page:


Cmdliner can be installed with opam:

opam install cmdliner

If you don't use opam consult the opam file for build instructions.


The documentation and API reference is automatically generated by from the source interfaces. It can be consulted online or via odig doc cmdliner.

Sample programs

If you installed Cmdliner with opam sample programs are located in the directory opam config var cmdliner:doc. These programs define the command line of some classic programs.

In the distribution sample programs are located in the test directory of the distribution. They can be built and run with:

topkg build --tests true && topkg test