[Openmcl-devel] where is shell output stored when launching an external program?

[Mark Cox]

Hi Clayton,

On Tue, Apr 17, 2012 at 11:00 AM, clayton stanley
<cstanley at cstanley.no-ip.biz> wrote:
> I am launching external processes with clozure common lisp. For better feedback/debugging, I would like to display the bash error string when I try to execute a nonexistent binary.

Can't this be solved using PROBE-FILE?

(defvar *path-to-program* nil)
(defun path-to-program ()
  (let ((v (probe-file (or *path-to-program*
			   (merge-pathnames (make-pathname :name "my-program"
							   :directory '(:relative "bin"))
					    (asdf:system-source-directory "my-system"))))))
    (unless v
      (error "PATH-TO-PROGRAM failed to find executable"))
    v))

(defun run-program (&rest args)
  (ccl:run-program (path-to-program) args))

Or substitute PROBE-FILE with a cross platform implementation of
FILE-EXISTS-AND-IS-EXECUTABLE-P?

Mark

>
> For example:
>
> ? (setf *t* (run-program "programDoesNotExist" '() :output t :error :output :wait nil))
> #<EXTERNAL-PROCESS (programDoesNotExist)[919] (RUNNING) #x302000E6471D>
>
> ? *t*
> #<EXTERNAL-PROCESS (programDoesNotExist)[919] (EXITED : 71) #x302000E6471D>
>
> ? (inspect *t*)
> [0]     #<EXTERNAL-PROCESS (programDoesNotExist)[919] (EXITED : 71) #x302000E6471D>
> [1]     Type: EXTERNAL-PROCESS
> [2]     Class: #<STRUCTURE-CLASS EXTERNAL-PROCESS>
> [3]     PID: 919
> [4]     %STATUS: :EXITED
> [5]     %EXIT-CODE: 71
> [6]     PTY: NIL
> [7]     INPUT: NIL
> [8]     OUTPUT: NIL
> [9]     ERROR: NIL
> [10]    STATUS-HOOK: NIL
> [11]    PLIST: NIL
> [12]    TOKEN: (0)
> [13]    CORE: NIL
> [14]    ARGS: ("programDoesNotExist")
> [15]    SIGNAL: #<SEMAPHORE #x302000E6483D>
> [16]    COMPLETED: #<SEMAPHORE #x302000E647BD>
> [17]    WATCHED-FDS: NIL
> [18]    WATCHED-STREAMS: NIL
> [19]    EXTERNAL-FORMAT: #<EXTERNAL-FORMAT NIL/:UNIX #x30200049FE9D>
> Inspect>
>
> Even with the inspector, I can't find the error information printed by the shell. I'm trying to recover this string in the lisp process:
>
> $ programDoesNotExist
> -bash: programDoesNotExist: command not found
>
> Any help would be greatly appreciated.
>
> Thanks,
> -Clayton
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