Command line parser

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Sébastien Gross


Sébastien Gross




Simple and easy to use modern command line argument parser for common lisp.


A typical command line consists of a program name, eventually options, sub-commands, sub-command options and a remaining.

A modern command line would look like:

./tool --verbose --chroot /path/to/dir server start --restart \
	--delay 10 instance1 instance2

A program get its argument by the mean of list (or a vector) of strings such as:

'("./tool" "--verbose" "--chroot" "/path/to/dir" "server" "start"
	"--restart" "--delay" "10" "instance1" "instance2")

It is up to the programmer's responsibility to parse and interpret the command line. We can split that command line into several parts:

  • The program name: ./tool. This is how the program is called.
  • Some global options: --verbose --chroot /path/to/dir. Each option can be a switch, such as --verbose, which is argument less, or can have one (or many) argument: /path/to/dir is an argument of the --chroot option.
  • A sub-command: server start. A sub command can be one or many verbs (or terms).
  • Some sub-command options: --restart --delay 10. This is the same as the global options but specific to the sub-command.
  • A rest: instance1 instance2 its the command line remains after parsing process.

CL-CLI usage

Basic usage

Think of a global option as a global variable as defined with DEFPARAMETER or DEFVAR. For example you would define *DEBUG*:

(defparameter *debug* nil "Run in debug mode")

Or in a more laconic way:

(defvar *debug*)

Now you only need to defined an option list suitable for CL-CLI:PARSE-CLI:

CL-USER> (defparameter *options*
'((*debug* nil "Run in debug mode" :alias ("-d"))
  (*dir* "/tmp" "Change to directory" :params ("DIR"))))

Now you can parse the command line:

CL-USER> (cl-cli:parse-cli '("./tool" "--dir" "/path/to/chroot" "--debug"
			      "server" "start" "--restart" "--delay" "3"
			      "instance1" "isntance2") *options*)
(T "/path/to/chroot")

The first two returned values are the variable list and their values suitable for PROGV. You can now bind these variables and execute code using the CL-CLI:WITH-ENVIRONMENT macro:

CL-USER> (multiple-value-bind (vars vals)
	     (cl-cli:parse-cli '("./tool" "--dir" "/path/to/chroot" "--debug"
				  "server" "start" "--restart" "--delay" "3"
				  "instance1" "isntance2") *options*)
	   (cl-cli:with-environment vars vals
				     (format t "dir: ~a, debug: ~a~%" *dir* *debug*)))
dir: /path/to/chroot, debug: T

The 3rd and 4th values are the sub-command to be run (if any, see below) and its arguments. The 5th value is the cli rest after parsing.

Advanced usage

A more advanced usage would use sub-commands. A sub-command defined by using CL-CLI:DEFCOMMAND which requires a dispatch verb list, an options list, a docstring and a body.

CL-USER> (cl-cli:defcommand
	     ("server" "start")
	     ((restart nil "restart instead of start")
	      (delay 2 "Second to wait" :params ("DELAY")))
	     "Start or restart server"
	   (when *debug*
	     (format t "Delay: ~a Restart: ~a~%" delay restart))
	   (format t "Server ~a in ~a~%"
		   (if restart "restarted" "started") *dir*)
   :VERBS ("server" "start")
   :OPTIONS ((RESTART NIL "restart instead of start")
             (DELAY 2 "Second to wait" :METAVARS ("DELAY")))
   :DOCSTRING "Start or restart server"

CL-CLI:DEFCOMMAND create the function and returns a CL-CLI:COMMAND structure:

CL-USER> (cl-cli:defcommand server-start
	     (:help "Start server"
	      :verbs ("server" "start")
	      :options ((restart :help "restart instead of start")
			(:name delay :default 2 :params ("DELAY") :help "Seconds to wait")))
  "Start or restart server"
  (when *debug*
    (format t "Delay: ~a Restart: ~a~%" delay restart))
  (format t "Server ~a in ~a~%" (if restart "restarted" "started") *dir*))
   :ARGS #<HASH-TABLE :TEST EQUAL :COUNT 2 {1006153A43}>
   :VERBS ("server" "start")
   :DOCSTRING "Start or restart server"
   :HELP "Start server")

A full working example would be something like:

CL-USER> (let ((options
	 (cl-cli:defoption '*debug* :default nil)
	 (cl-cli:defoption '*dir* :default "/tmp" :params '("DIR"))))
      (argv '("./tool" "--dir" "/path/to/chroot" "--debug"
	      "server" "start" "--restart" "--delay" "3"
	      "instance1" "isntance2"))
	(list (cl-cli:defcommand server-start
		  (:help "Start server"
		   :verbs ("server" "start")
		   :options ((restart
			      :help "restart instead of start")
			     (delay :default 2 :params '("DELAY")
			      :help "Seconds to wait")))
		"Start or restart server"
		(when *debug*
		  (format t "Delay: ~a Restart: ~a~%" delay restart))
		(format t "Server ~a in ~a~%"
			(if restart "restarted" "started") *dir*))
	      (cl-cli:defcommand server-stop
		  (:help "Stop server"
		   :verbs ("server" "stop")
		   :options ((:name delay :default 2 :params '("DELAY")
			      :help "Seconds to wait")))
		"Stop server"
		(when *debug*
		  (format t "Delay: ~a~%" delay))
		(format t "Server stopped in ~a~%" *dir*)))))
  (cl-cli:run (:argv argv :options options :sub-commands sub-commands)))

Delay: 3 Restart: T
Server restarted in /path/to/chroot


The options list

This is a list of options you pass to te parser. Each option is defined as:

(name default help &key long alias params type)
  • name: the option name, or variable to which the option is bound to.
  • default: The option default value.
  • help: a docstring that is used to display help.
  • long: the option long form generated against name. For example *foo-bar*: will result as --foo-bar.
  • alias: a list of option aliases. This is a good place to define shortcuts such as -f for --foo or -b for --bar.
  • params: a list of option parameters that define how many arguments the option requires. If params is nil no option is required. n the other hand if you need to defined a chroot diretory you can setup params to ("dir"). Thus --chroot requires one mandatory argument. The "dir" string is used in help display.
  • type: A type to which the option should be converted to.

The commands list

As for options, the command list defined all known commands the parser should be aware of. A command is created using the CL-CLI:DEFCOMMAND macro.

(defcommand verbs options positional docstring func)
  • verbs: A list of words that triggers the command.
  • options: a list of command options.
  • positional: a list of mandatory positional arguments (order maters). This is like an option but with no default value.
  • docstring: a string that is used to display help.
  • func: a function body that should handle the command.



parse-cli (argv &optional options commands)

Parse ARGV using OPTIONS both and COMMANDS directives.


  • options variables
  • options values
  • matched command dispatch function
  • dispatch function keyword arguments
  • the rest of the command line argument"


with-environment (vars vals &body body)

Run BODY after binding VARS to VALS.

The 2 first values of parse-cli can be used to feen with-environment.


run-command (argv &optional options commands)

Run parse-cli and execute the matched dispatch function.


help (options sub-commands &key prog-name version prolog epilog)

Display help screen.

  • prog-name: the program name.
  • version: the program version.
  • prolog: a text that should be displayed at the beging.
  • epilog: a text that should be diplayed at the end.


Author: Sébastien Gross <seb•ɑƬ•chezwam•ɖɵʈ•org> License: WTFPL, grab your copy here:

Dependencies (1)

  • split-sequence

Dependents (0)

    • GitHub
    • Quicklisp