babashka

A sprinkle of Clojure for the command line.

Quickstart

$ bash <(curl -s https://raw.githubusercontent.com/borkdude/babashka/master/install)
$ bb '(vec (dedupe *in*))' <<< '[1 1 1 1 2]'
[1 2]

Rationale

If you're a bash expert, you probably don't need this. But for those of us who can use a bit of Clojure in their shell scripts, it may be useful.

Babashka runs as a binary and uses sci for interpreting Clojure, which results in faster startup times:

$ time clojure -e "(require '[clojure.java.shell :as shell])" ./download_html.clj
2.15s user 0.17s system 242% cpu 0.959 total

$ time bb -f ./download_html.clj
0.00s user 0.00s system 69% cpu 0.010 total

A trade-off is that sci implements only a subset of Clojure. If you need more, feel free to post an issue or check out other Clojure scripting projects.

Status

Experimental. Breaking changes are expected to happen at this phase.

Installation

Brew

Linux and macOS binaries are provided via brew.

Install:

brew install borkdude/brew/babashka

Upgrade:

brew upgrade babashka

Installer script

Install via the installer script:

$ bash <(curl -s https://raw.githubusercontent.com/borkdude/babashka/master/install)

By default this will install into /usr/local/bin. To change this, provide the directory name:

$ bash <(curl -s https://raw.githubusercontent.com/borkdude/babashka/master/install) /tmp

Download

You may also download a binary from Github.

Usage

bb [ --help ] | [ --version ] | ( [ -i ] [ -o ] | [ -io ] ) [ --stream ] ( expression | -f <file> )

Type bb --help to see a full explanation of the options.

The input is read as EDN by default. If the -i flag is provided, then the input is read as a string which is then split on newlines. The output is printed as EDN by default, unless the -o flag is provided, then the output is turned into shell-scripting friendly output. To combine -i and -o you can use -io. When using the --stream option the expression is executed for every line or EDN value from stdin.

The clojure.core functions are accessible without a namespace alias.

The following Clojure namespaces are required by default and only available through the aliases:

• clojure.string aliased as str
• clojure.set aliased as set
• clojure.edn aliased as edn (only read-string is available)
• clojure.java.shell aliases as shell (only sh is available)

From Java the following is available:

• System: exit, getProperty, getProperties, getenv

Special vars:

• *in*: contains the input read from stdin (EDN by default, multiple lines with the -i option)

• *command-line-args*: contain the command line args

Examples:

$ ls | bb -i '*in*'
["LICENSE" "README.md" "bb" "doc" "pom.xml" "project.clj" "reflection.json" "resources" "script" "src" "target" "test"]

$ ls | bb -i '(count *in*)'
12

$ bb '(vec (dedupe *in*))' <<< '[1 1 1 1 2]'
[1 2]

$ bb '(filterv :foo *in*)' <<< '[{:foo 1} {:bar 2}]'
[{:foo 1}]

$ bb '(#(+ %1 %2 %3) 1 2 *in*)' <<< 3
6

$ ls | bb -i '(filterv #(re-find #"reflection" %) *in*)'
["reflection.json"]

$ bb '(run! #(shell/sh "touch" (str "/tmp/test/" %)) (range 100))'
$ ls /tmp/test | bb -i '*in*'
["0" "1" "10" "11" "12" "13" "14" "15" "16" "17" "18" "19" "2" "20" "21" ...]

More examples can be found in the gallery.

Running a file

Scripts may be executed from a file using -f or --file:

bb -f download_html.clj

Using bb with a shebang also works:

#!/usr/bin/env bb -f

(defn get-url [url]
  (println "Fetching url:" url)
  (let [{:keys [:exit :err :out]} (shell/sh "curl" "-sS" url)]
    (if (zero? exit) out
      (do (println "ERROR:" err)
          (System/exit 1)))))

(defn write-html [file html]
  (println "Writing file:" file)
  (spit file html))

(let [[url file] *command-line-args*]
  (when (or (empty? url) (empty? file))
    (println "Usage: <url> <file>")
    (System/exit 1))
  (write-html file (get-url url)))

(System/exit 0)

$ ./download_html.clj
Usage: <url> <file>

$ ./download_html.clj https://www.clojure.org /tmp/clojure.org.html
Fetching url: https://www.clojure.org
Writing file: /tmp/clojure.org.html

Test

Test on the JVM:

script/test

Although this tool doesn't offer any benefit when running on the JVM, it is convenient for development.

Test the native version:

BABASHKA_TEST_ENV=native script/test

Build

You will need leiningen and GraalVM.

script/compile

Related projects

• planck
• joker
• closh
• lumo

Gallery

Here's a gallery of more useful examples. Do you have a useful example? PR welcome!

Shuffle the lines of a file

$ cat /tmp/test.txt
1 Hello
2 Clojure
3 Babashka
4 Goodbye

$ < /tmp/test.txt bb -io '(shuffle *in*)'
3 Babashka
2 Clojure
4 Goodbye
1 Hello

Fetch latest Github release tag

For converting JSON to EDN, see jet.

$ curl -s https://api.github.com/repos/borkdude/babashka/tags |
jet --from json --keywordize --to edn |
bb '(-> *in* first :name (subs 1))'
"0.0.4"

Get latest OS-specific download url from Github

$ curl -s https://api.github.com/repos/borkdude/babashka/releases |
jet --from json --keywordize |
bb '(-> *in* first :assets)' |
bb '(some #(re-find #".*linux.*" (:browser_download_url %)) *in*)'
"https://github.com/borkdude/babashka/releases/download/v0.0.4/babashka-0.0.4-linux-amd64.zip"

Support this project

Do you enjoy this project? Consider buying me a hot beverage.

License

Copyright © 2019 Michiel Borkent

Distributed under the EPL License, same as Clojure. See LICENSE.