Unix-style command line options parser

License MIT Quicklisp

This is a minimalistic parser of command line options. The main advantage of this library is ability to concisely define command line options once and then use this definition for parsing and extraction of command line arguments, as well as printing description of command line options (you get --help for free). This way you don't need to repeat yourself. Also, unix-opts doesn't depend on anything and allows to precisely control behavior of the parser via Common Lisp restarts.

Inspired by Haskell's optparse-applicative and Python's argparse.


Copy files of this library in any place where ASDF can find them. Then you can use it in system definitions and ASDF will take care of the rest.

Via Quicklisp (recommended):

(ql:quickload "unix-opts")


option condition

Take a condition condition (unknown-option, missing-arg, or arg-parser-failed) and return string representing option in question.

raw-arg condition

Take a condition of type arg-parser-failed and return raw argument string.

define-opts &rest descriptions

Define command line options. Arguments of this macro must be plists containing various parameters. Here we enumerate all allowed parameters:

:name ? keyword that will be included in list returned by get-opts function if actual option is supplied by user.

:description ? description of the option (it will be used in describe function). This argument is optional, but it's recommended to supply it.

:short ? single character, short variant of the option. You may omit this argument if you supply :long variant of option.

:long ? string, long variant of option. You may omit this argument if you supply :short variant of option.

:arg-parser ? if actual option must take an argument, supply this argument, it must be a function that takes a string and parses it.

:meta-var ? if actual option requires an argument, this is how it will be printed in option description.


Return list of program's arguments, including command used to execute the program as first elements of the list.

get-opts &optional options

Parse command line options. If options is given, it should be a list to parse. If it's not given, the function will use argv function to get list of command line arguments. Return two values: list that contains keywords associated with command line options with define-opts macro, and list of free arguments. If some option requires an argument, you can use getf to test presence of the option and get its argument if the option is present.

The parser may signal various conditions, let's list them all specifying which restarts are available for every condition, and what kind of information the programmer can extract from the conditions.

unknown-option is thrown when parser encounters unknown (not previously defined with define-opts) option. Use option reader to get name of the option (string). Available restarts: use-value (substitute the option and try again), skip-option (ignore the option).

missing-arg is thrown when some option wants an argument, but there is no such argument given. Use option reader to get name of the option (string). Available restarts: use-value (supplied value will be used), skip-option (ignore the option).

arg-parser-failed is thrown when some option wants an argument, it's given but cannot be parsed by argument parser. Use option reader to get name of the option (string) and raw-arg to get raw string representing the argument before parsing. Available restarts: use-value (supplied value will be used), skip-option (ignore the option), reparse-arg (supplied string will be parsed instead).

describe &key prefix suffix usage-of args stream

Return string describing options of the program that were defined with define-opts macro previously. You can supply prefix and suffix arguments that will be printed before and after options respectively. If usage-of is supplied, it should be a string, name of the program for "Usage: " section. This section is only printed if this name is given. If your program takes arguments (apart from options), you can specify how to print them in "Usage: " section with args option (should be a string designator). Output goes to stream (default value is *standard-output*).


Go to example directory. Now, you can use example.lisp file to see if unix-opts is cool enough for you to use. SBCL users can use example.sh file. Here is some tests:

$ sh example.sh --help
example ? program to demonstrate unix-opts library

Usage: example.sh [-h|--help] [-v|--verbose] [-l|--level LEVEL]
                  [-o|--output FILE] [FREE-ARGS]

Available options:
  -h, --help               print this help text
  -v, --verbose            verbose output
  -l, --level LEVEL        the program will run on LEVEL level
  -o, --output FILE        redirect output to file FILE

so that's how it works?
free args:
$ sh example.sh -v file1.txt file2.txt
OK, running in verbose mode?
free args: file1.txt, file2.txt
$ sh example.sh --level 10 --output foo.txt bar.txt
I see you've supplied level option, you want 10 level!
I see you want to output the stuff to "foo.txt"!
free args: bar.txt
$ sh example.sh --level kitty foo.txt
fatal: cannot parse "kitty" as argument of "--level"
free args:
$ sh example.sh --hoola-boola noola.txt
warning: "--hoola-boola" option is unknown!
free args: noola.txt
$ sh example.sh -vgl=10
warning: "-g" option is unknown!
OK, running in verbose mode?
I see you've supplied level option, you want 10 level!
free args:

Take a look at example.lisp and you will see that the library is pretty sexy! Basically, we have defined all the options just like this:

  (:name :help
   :description "print this help text"
   :short #\h
   :long "help")
  (:name :verbose
   :description "verbose output"
   :short #\v
   :long "verbose")
  (:name :level
   :description "the program will run on LEVEL level"
   :short #\l
   :long "level"
   :arg-parser #'parse-integer
   :meta-var "LEVEL")
  (:name :output
   :description "redirect output to file FILE"
   :short #\o
   :long "output"
   :arg-parser #'identity
   :meta-var "FILE"))


Copyright ? 2015?2017 Mark Karpov

Distributed under MIT License.

Mark Karpov
command-line options parser, console, library, system programming