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 which results in faster startup times:

$ time clojure -e "(+ 1 2 3)"
6
clojure -e "(+ 1 2 3)"  3.29s user 0.32s system 99% cpu 3.638 total

$ time plk -e '(+ 1 2 3)'
6
plk -e '(+ 1 2 3)'  1.34s user 0.16s system 127% cpu 1.172 total

$ time bb '(+ 1 2 3)'
6
bb '(+ 1 2 3)'  0.01s user 0.01s system 37% cpu 0.046 total

It uses sci for interpreting Clojure. A trade-off is that sci implements only a subset of Clojure. Also, execution time may be slower than Clojure on the JVM or (self-hosted) ClojureScript for more CPU-intensive calculations like:

(last (take 1000000 (repeatedly #(+ 1 2 3))))

This would take 5 seconds using babashka, around half a second using self-hosted ClojureScript and around 200ms in Clojure on the JVM.

So the sweet spot for babashka is executing tasks from the command line where fast startup time is preferred, in the same space where you would use bash.

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 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, setProperty, 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

Enabling SSL

If you want to be able to use SSL to e.g. run (slurp "https://www.clojure.org") you will need to add the location where libsunec.so or libsunec.dylib is located to the java.library.path Java property. This library comes with most JVM installations, so you might already have it on your machine. It is usually located in <JAVA_HOME>/jre/lib or <JAVA_HOME>/jre/<platform>/lib. It is also bundled with GraalVM.

Example:

$ cat /tmp/https_get.clj
#!/usr/bin/env bb -f

(System/setProperty
 "java.library.path"
 "/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home/jre/lib")

(slurp (first *command-line-args*))

$ /tmp/https_get.clj https://www.google.com | bb '(subs *in* 0 50)'
"<!doctype html><html itemscope=\"\" itemtype=\"http:/"

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.

This repo contains a submodule, so you will have clone that too. If you're doing that for the first time:

$ git submodule update --init --recursive

and for subsequent updates:

$ git submodule update --recursive

To build this project, set $GRAALVM_HOME to the GraalVM distribution directory.

Then run:

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.