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How can I get the command line arguments in (specifically in GNU, if there are any differences) Common Lisp?

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  • For next googlers: there's the mentioned CLON library, now also the simpler unix-opts, and a tutorial. Commented Jun 19, 2018 at 15:23

7 Answers 7

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28

http://cl-cookbook.sourceforge.net/os.html provides some insight

  (defun my-command-line ()
  (or 
   #+CLISP *args*
   #+SBCL *posix-argv*  
   #+LISPWORKS system:*line-arguments-list*
   #+CMU extensions:*command-line-words*
   nil))

is what you are looking for, I think.

(edit): see the newer Cookbook: https://lispcookbook.github.io/cl-cookbook/scripting.html

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4 Comments

(or FOO nil) is equivalent to FOO, is it not?
Yes, but when you have your FOO conditionally read, it's, possibly, good to have a fall-back. But, then, the value of (or) is, not entirely surprising, NIL (just as the value of (and) is T).
For some reason this doesn't work for clisp for me: *** - OR: variable *ARGS* has no value
@aragaer You might have been getting that error because the code you were trying to run was in its own package that doesn't have all the default symbols available. *args* is defined in ext. clisp -q -x '(defpackage :foo)' -x '(in-package :foo)' -x '*args*' gets that error, but if you change it to ext:*args* or import it or whatever, it should work.
20

I'm assuming that you are scripting with CLisp. You can create a file containing

#! /usr/local/bin/clisp
(format t "~&~S~&" *args*)

Make it executable by running 

$ chmod 755 <filename>

Running it gives

$ ./<filename>
NIL
$ ./<filename> a b c
("a" "b" "c")
$ ./<filename> "a b c" 1 2 3
("a b c" "1" "2" "3")
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3 Comments

the link in this post is no longer viable. :(
this is super cool. but how can i make data from the strings? my function is used to inputs like this (unique '(a b c c d d d e f)) and it doesn't work with strings :O .. i tried to (mapcar #'make-symbol args) but that doesn't seem to do the job
I had troubles using *args*. If you have to you might want to check the special variable name to use with your interpreter. For instance, *args* works for clisp, but if you use sbcl, *posix-argv* is apparently what you want.
4

Are you talking about Clisp or GCL? Seems like in GCL the command line arguments get passed in si::*command-args*.

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4

In SBCL,we can use sb-ext:*posix-argv* to get the argv from a Common Lisp script. sb-ext:*posix-argv* is a list holding all the arguments, the first member of the list is the script filename.

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2 Comments

I'm not sure this works anymore. I get the error message 'Symbol "POSIX-ARGV" not found in the SB-EXT package.'
should be sb-ext:*posix-argv*, in the old text, the *something* worked as a style. I'm sorry.
3

A portable way is uiop:command-line-arguments (available in ASDF3, shipped by default in all major implementations).

Libraries-wise, there is the mentioned Clon library that abstracts mechanisms for each implementation, and now also the simpler unix-opts, and a tutorial on the Cookbook.

(ql:quickload "unix-opts")

(opts:define-opts
    (:name :help
       :description "print this help text"
       :short #\h
       :long "help")
    (:name :nb
       :description "here we want a number argument"
       :short #\n
       :long "nb"
       :arg-parser #'parse-integer) ;; <- takes an argument
    (:name :info
       :description "info"
       :short #\i
       :long "info"))

Then actual parsing is done with (opts:get-opts), which returns two values: the options, and the remaining free arguments.

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2

As seen in https://stackoverflow.com/a/1021843/31615, each implementation has its own mechanism. The usual way to deal with this is to use a wrapper library that presents a unified interface to you.

Such a library can provide further assistance in not only reading things in, but also converting them and giving helpful output to the user. A quite complete package is CLON (not to be confused with CLON or CLON, sorry), the Command Line Options Nuker, which also brings extensive documentation. There are others, though, should your needs be more lightweight, for example, command-line-arguments and apply-argv.

The packages in quicklisp for these are named net.didierverna.clon, command-line-arguments, and apply-argv, respectively.

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0

Just go for it on SBCL (2.1.11.debian):

(defun main ()
    (let (
        (args sb-ext:*posix-argv*))

    (format t "args = ~a~%" args)))

(main)
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