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 ] ) ( 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
.
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 asstr
-
clojure.set
aliased asset
-
clojure.edn
aliased asedn
(onlyread-string
is available) -
clojure.java.shell
aliases asshell
(onlysh
is available)
From Java the following is available:
-
System
:exit
,getProperty
,getProperties
,getenv
Special vars:
-
*in*
: contains the input read from stdin -
*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
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.