Input isn't passed to the external program

[ekd123]

(external-program:run "cat" nil :input *standard-input*)

You see, no matter how I hit enter, cat won't print anything.
Is it a bug? How to work it around?

[sellout]

Which CL implementation are you using?

First, you are not telling the output to go anywhere. It’s also possible that you are not actually typing your input into wherever *standard-input* is coming from. Try

(external-program:run "cat" nil
                      :input (make-string-input-stream "foo")
                      :output *standard-output*)

Hopefully that will work. If it does, then try

(external-program:run "cat" nil
                      :input *standard-input*
                      :output *standard-output*)

If that doesn’t work, then the problem is that wherever you are typing is not connected to *standard-input*.

You could also try unwrapping the call to see how the underlying CL implementation behaves. EG, on CCL it would be:

(ccl:run-program "cat" nil
                 :input (make-string-input-stream "foo")
                 :output *standard-output*
                 :wait t)

If that has the same behavior as external-program:run, then the problem is likely in how you are using the function (or, less likely, in the CL implementation).

[ekd123]

Result: the 1st and the 3rd work, but the 2nd doesn't work. (I'm using SBCL)

(sb-ext:run-program "/usr/bin/cat" nil 
                    :input (make-string-input-stream "foo") 
                    :output *standard-output*)

prints "foo" as I expected.

(read-line *standard-input*)

reads one line as I expected.

but

(sb-ext:run-program "/usr/bin/cat" nil 
                    :input *standard-input* 
                    :output *standard-output* :wait t)

won't run.

[epipping]

sbcl \
  --eval '(require :external-program)' \
  --eval '(external-program:run "cat" nil :input (make-string-input-stream (format nil "foo~%")) :output *standard-output*)' \
  --quit

Prints foo and a newline for me, like it should.

echo foo | sbcl \
  --eval '(require :external-program)' \
  --eval '(external-program:run "cat" nil :input *standard-input* :output *standard-output*)' \
  --quit

Also prints foo and a newline for me, like it should.

I think there is no bug here.