[Libguestfs] [PATCH 1/2] mllib: allow external_command to return [] on nonzero return value

[Richard W.M. Jones]

On Wed, Mar 18, 2015 at 05:20:06PM +0100, Maros Zatko wrote:
> This is useful for probing probing for cache files such as:
> external_command ?ignore_error:(Some true) ~prog "ls .cache/something.*"
> will return command output (matched files) on its success or empty list
> whenits exit code is other than 0 (there are no such files).

I would write this as:

  let files = Sys.readdir ".cache" inm
  let files = Array.to_list files in
  let files = List.filter (fun s -> string_prefix s "something.") in

  (*
  or if you just want to check existence of any something.* file:

  let file_exists = List.exists (fun s -> string_prefix s "something.") in
  *)

Rich.

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