The type for specifying program exits. Either an exit code or a function (should be) calling B00_std.Cmd.execv.

code c is Code c.

exec ?env ?cwd file argv is an Exec _. That has a call to Os.Cmd.execv with the corresponding arguments.

get_code e is the exit code of e. Raises Invalid_argument if e is Exec.

exit e exits according to e:

• If e is Code c, Stdlib.exit c is called and the function never returns.
• If e is Exec execv, execv is called. This can only return with an Error _. In that case log it and call the function again with an error code - this guarantees termination.

on_sigint ~hook f calls f () and returns its value. If SIGINT is signalled during that time hook is called followed by exit 130 – that is the exit code a SIGINT would produce.

on_sigint replaces an existing signal handler for Sys.sigint during time of the function call. It is restored when the function returns.

Note. Since Stdlib.exit is called Stdlib.at_exit functions are called if a SIGINT occurs during the call to f. This is not the case on an unhandled SIGINT.