Command-line processing
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tools.cli is a command line argument parser for Clojure.

Releases and Dependency Information

Latest stable release: 0.2.2

Leiningen dependency information:

[org.clojure/tools.cli "0.2.2"]

Maven dependency information:


Example Usage

(use '[ :only [cli]])

(cli args
     ["-p" "--port" "Listen on this port" :parse-fn #(Integer. %)] 
     ["-h" "--host" "The hostname" :default "localhost"]
     ["-v" "--[no-]verbose" :default true]
     ["-l" "--log-directory" :default "/some/path"])

with args of:

["-p" "8080"
 "--log-directory" "/tmp"

will return a vector containing three elements:

a clojure map with the names picked out for you as keywords:

 {:port          8080
  :host          "localhost"
  :verbose       false
  :log-directory "/tmp"}

a vector of trailing arguments that are not options:


and a documentation string to use to provide help:


 Switches                    Default     Desc          
 --------                    -------     ----          
 -p, --port                              Listen on this port              
 -h, --host                  localhost   The hostname     
 -v, --no-verbose --verbose  true                      
 -l, --log-directory         /some/path"   


An option is specified by providing a vector of information:

Switches should be provided first, from least to most specific. The last switch you provide will be used as the name for the argument in the resulting hash-map. The following:

["-p" "--port"]

defines an argument with two possible switches, the name of which will be :port in the resulting hash-map.

Next is an optional doc string:

["-p" "--port" "The port to listen on"]

This will be printed in the 'Desc' column of the help banner.

Following that are optional parameters, provided in key-value pairs:

["-p" "--port" "The port to listen on" :default 8080 :parse-fn #(Integer. %)]

These should be self-explanatory. The defaults if not provided are as follows:

{:default  nil
 :parse-fn identity
 :flag     false}

Boolean Flags

Flags are indicated either through naming convention:

["-v" "--[no-]verbose" "Be chatty"]

(note the [no-] in the argument name).

Or you can explicitly mark them as flags:

["-v" "--verbose" "Be chatty" :flag true]

Either way, when providing them on the command line, using the name itself will set to true, and using the name prefixed with 'no-' will set the argument to false:

(cli ["-v"]
     ["-v" "--[no-]verbose"])

=> [{:verbose true}, ...]

(cli ["--no-verbose"]
     ["-v" "--[no-]verbose"])

=> [{:verbose false}, ...]

Note: there is no short-form to set the flag to false (-no-v will not work!).

Trailing Arguments

Any trailing arguments given to cli are returned as the second item in the resulting vector:

(cli ["--port" "9999" "some" "extra" "arguments"]
     ["--port" :parse-fn #(Integer. %)])

=> [{:port 9999}, ["some" "extra" "arguments"], ...]

This allows you to deal with parameters such as filenames which are commonly provided at the end of an argument list.

If you with to explicitly signal the end of arguments, you can use a double-hyphen:

(cli ["--port" "9999" "--" "some" "--extra" "arguments"]
     ["--port" :parse-fn #(Integer. %)])

=> [{:port 9999}, ["some" "--extra" "arguments"], ...]

This is useful when your extra arguments look like switches.


The third item in the resulting vector is a banner useful for providing help to the user:

(let [[options args banner] (cli ["--faux" "bar"]
                                 ["-h" "--help" "Show help" :default false :flag true]
                                 ["-f" "--faux" "The faux du fafa"])]
  (when (:help options)
    (println banner)
    (System/exit 0))
  (println options))

Developer Information

Change Log

  • Release 0.2.2 on 2012-08-09
    • Applying patch for TCLI-1 (do not include keys when no value provided by :default)
  • Release 0.2.1 on 2011-11-03
    • Removing the :required option. Hangover from when -h and --help were implemented by default, causes problems if you want help and dont provide a :required argument.
  • Release 0.2.0 on 2011-10-31
    • Remove calls to System/exit
    • Remove built-in help options
  • Release 0.1.0
    • Initial import of Clargon codebase


Copyright (c) Rich Hickey and contributors. All rights reserved.

The use and distribution terms for this software are covered by the Eclipse Public License 1.0 ( which can be found in the file epl.html at the root of this distribution. By using this software in any fashion, you are agreeing to be bound by the terms of this license. You must not remove this notice, or any other, from this software.