B0 actions manual

This manual shows how to deal with B0 actions and how to create your own.


Basic operations on actions are provided by the b0 action command.

b0 action list  # List action

Running an action is

Action, tool or executable unit ?

XXX clarify terminology and formally define executable unit (or eschew the concept and only keep tool).

From the point of user interface there's not much difference between you all call them the same way which is:

b0 -- NAME ARG…

Actions may involve a build or not, invoking a tool described by a unit automatically builds it and runs the tool. The b0 list command lists both tools an actions (except the library actions for which you need --all. If you want to see specific listings

b0 list        # Actions, build units, build packs
b0 list --all  # Also include library actions
b0 action list # List only actions
b0 tool list   # List public tools and private tools in the root scopexs

Making your own action

Let's make a simple action a script at the root of your project:

Yaddada root vs scope

let run_script script _ env ~args =
  let cwd = B0_env.scope_dir env in
  let script = B0_env.in_scope_dir env script in
  Os.Exit.exec ~cwd script Cmd.(path script %% args)

let mycmd =
  B0_action.make "mycmd" ~doc:"Run mycmd" @@
  run_script ~/"scripts/mycmd"

Even though you should rewrite all these scripts as OCaml actions a direct short cut for the above boilerplate is provided. Use B0_action.exec_file:

let mycmd =
  B0_action.make "mycmd" ~doc:"Run mycmd" @@
  B0_action.exec_file ~/"scripts/mycmd"


Run a unit executable in an action

let myunit = …
let action
  let doc = "That's particular" in
  B0_action.make' "my-exec" ~units:[myunit] ~doc @@ fun _ env ~args ->
  let* cmd = B0_env.unit_cmd myunit in
  Os.Cmd.run cmd