cmdliner-stdlib

The cmdliner-stdlib package is a collection of cmdliner terms that help control OCaml runtime parameters, usually configured through the OCAMLRUNPARAM environment variable. The package provides command-line options for controlling features like backtrace, hash table randomization, and garbage collector tuning.

Installation

You can install the package using opam:

opam install cmdliner-stdlib

Usage

You can use these command-line arguments to:

• enable/disable backtraces;
• enable/disable table randomization, for better security and prevent collision attacks; and
• control the OCaml garbage collector as described in detail in the GC control documentation.

open Cmdliner

let cmd = Cmd.v (Cmd.info "hello") (Cmdliner_stdlib.setup ())
let () = exit (Cmd.eval cmd)

You can then use command-line options to change parameters of the OCaml runtime. For instance, to enable backtraces and change the GC allocation policy to "first fit":

$ dune exec -- ./hello.exe --allocation-policy=first-fit --backtrace=true

You can disable some of these arguments. For instance, to disable GC control use:

   Cmdliner_stdlib.setup ~gc_control:None ()

Or to change the default allocation policy to be first-fit:

  let default = Gc.get () in
  let gc_control = Some { default with allocation_policy = 1 } in
  Cmdliner_stdlib.setup ~gc_control ()

Contributions

We welcome contributions, bug reports, and feature requests. Please visit our GitHub repository for more information.