Executing a shell command from Common Lisp

Question

How can i execute a shell (bash) command within a Common Lisp program and assign the output to a variable?

Answer 1

You can consider using Trivial-shell (url)

(trivial-shell:shell-command "echo foo")

shell-command returns output, so you can assign it to a variable.

In asdf.lisp file you can read:

;;;; We probably should move this functionality to its own system and deprecate

;;;; use of it from the asdf package. However, this would break unspecified

;;;; existing software, so until a clear alternative exists, we can't deprecate

;;;; it, and even after it's been deprecated, we will support it for a few

;;;; years so everyone has time to migrate away from it. -- fare 2009-12-01

Answer 2

ASDF provides a RUN-SHELL-COMMAND that works with many Common Lisp implementations including ABCL, Allegro CL, CLISP, Clozure CL, ECL, GCL, LispWorks, SBCL, CMU, XCL and SCL.

It takes a control string and a list of arguments like FORMAT, and synchronously executes the result using a Bourne-compatible shell. Capture output by binding an optional stream.

Answer 3

I tried out some answers but it was not straightforward. This is what worked easily:

(ql:quickload "external-program")
;; run shell command e.g. "ls -l" and capture the output into string *output*
(defparameter *output* 
              (with-output-to-string (out) 
                (external-program:run "ls" '("-l")  ; command with parameters as list of strings
                                      :output out)))
;; and after that, you can write functions to parse the output ...

This is from Edi Weitz's book Common Lisp Recipes which belongs to the shelve of any serious Lisp programmer, in my view...

Answer 4

In sbcl:

(sb-ext:run-program "/bin/sh" (list "-c" "whoami") :input nil :output *standard-output*)

It works fine for me:)

Answer 5

Some CL implementations have built-in functions for this purpose. For example, SBCL has sb-ext:run-program, and CCL has run-program.

Answer 6

Nowadays I would use uiop:run-program, where uiop stands for "universal input output" and is a compatibility layer provided by asdf3, formerly known as asdf/driver. As has been said asdf:run-shell-command is obsolete and uiop inherits many features of other libraries such as trivial-shell.

UIOP readme