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I'd like to run an interactive CLI program from within Clojure (e.g., vim) and be able to interact with it.

In bash and other programming languages, I can do that with

vim > `tty`

I tried to do the same in Clojure:

(require '[clojure.java.shell :as shell])
(shell/sh "vim > `tty`")

but it just opens vim without giving me tty.

Background: I'm developing a Clojure CLI tool which parses emails and lets a user edit the parsed data before saving them on the disk. It works the following way:

  1. Read a file with email content and parse it. Each email is stored as a separate file.
  2. Show a user the parsed data and let the user edit the data in vim. Internally I create a temporary file with the parsed data, but I don't mind doing it another way if that would solve my issue.
  3. After a user finished editing the parsed data (they might decide to keep it as it is) append the data to a file on a disk. So all parsed data are saved to the same file.
  4. Go to 1st step if there are any files with emails left.
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    For vim/clojure interaction, look up fireplace Commented Jun 11, 2019 at 15:55
  • @AlanThompson thanks for your suggestion! Unfortunately, it isn't what I'm looking for. I added more background information to my question. Commented Jun 12, 2019 at 9:49
  • Can you add more background? If I understand correctly your program generates some files; let users edit them; then process the edited data(?). If so, you could dump your data in some temporary file, then fire e.g. (or (System/getenv "EDITOR") "vim") on the file; then read the file in your program when the user has saved the file and closed their editor. This is how git commit works. Commented Jun 18, 2019 at 11:45
  • Sure. I added more information about the program. I hope that helps! The issue is that I can't fire vim or any other editor from within Clojure program while also letting a user interact with this editor. Commented Jun 18, 2019 at 15:27

1 Answer 1

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This code relies on Clojure Java interop to make use of Java's ProcessBuilder class.

(defn -main
[]
;use doseq instead of for because for is lazily evaluated
(doseq [i [1 2 3]]
;extract current directory from system variable
(let [file-name (str "test" i ".txt")
      working-directory (trim-newline (:out (sh "printenv" "PWD")))]
  (spit file-name "")

  ;this is where fun begins. We use ProcessBuilder to forward commands to terminal
  ;we pass a list of commands and their arguments to its constructor
  (let [process-builder (java.lang.ProcessBuilder. (list "vim" (str working-directory "/" file-name)))
  ;inherit is a configuration constant
        inherit (java.lang.ProcessBuilder$Redirect/INHERIT)]
  ;we configure input, output and error redirection
  (.redirectOutput process-builder inherit)
  (.redirectError process-builder inherit)
  (.redirectInput process-builder inherit)

  ;waitFor used to block execution until vim is closed
  (.waitFor (.start process-builder))
  )
  ;additional processing here
)
)
;not necessary but script tends to hang for around 30 seconds at end of its execution
;so this command is used to terminate it instantly
(System/exit 0)
)
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