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safely use rsync --archive --delete to backup a directory
#!/usr/bin/env bb
(ns backup-directory-dangerously
(:require [babashka.cli :as cli]
[babashka.fs :as fs]
[babashka.process :as p]
[clojure.java.io :as io]
[clojure.string :as str]))
(defn abort []
(println "Aborting backup")
(System/exit 1))
(defn confirm [prompt]
(print prompt "[y/N]: ")
(flush)
(when (not= "y" (-> (io/reader *in*) line-seq first))
(abort)))
(defn print-help [spec]
(println "backup-directory-dangerously <src> <dest>")
(println (cli/format-opts {:spec spec :order [:source :dest]})))
(def spec {:source {:desc "An existing directory to backup."
:ref "<path>"}
:dest {:desc "An existing directory or nonexistent path to backup to. If already existing, contents will be overwritten and lost forever."
:ref "<path>"}})
(when (= '("--help") *command-line-args*)
(print-help spec)
(System/exit 0))
(def cli-opts {:spec spec
:args->opts [:source :dest]
:require [:source :dest]
:restrict [:source :dest]
:validate {:source {:pred fs/directory?
:ex-msg #(str "Must be existing directory: "
(-> % :value fs/canonicalize))}
:dest {:pred #(or (fs/directory? %) (not (fs/exists? %)))
:ex-msg #(str "Must be existing directory or nonexistent path: "
(-> % :value fs/canonicalize))}}
:error-fn (fn [{:keys [_spec _type _cause msg _option]}]
(println "ERROR:" msg)
(println)
(print-help spec)
(System/exit 1))})
(def parsed-args (cli/parse-args *command-line-args* cli-opts))
(def source (-> parsed-args :opts :source fs/canonicalize str))
(def dest (-> parsed-args :opts :dest fs/canonicalize str))
(println "Source directory:" source)
(println "Destination directory:" dest)
(println)
(if (fs/directory? dest)
(do (println "Destination directory exists and has these contents:")
(-> (p/process ["ls" "-lahA" dest])
(p/process ["head"])
p/check
:out
slurp
println)
(confirm (str "Do you really want to overwrite " dest "?")))
(println "Destination directory does not exist and will be created"))
(def rsync-command ["rsync" "--archive" "--verbose" "--human-readable" "--progress" "--one-file-system" "--delete" (str source "/") dest])
(println)
(println (str/join " " rsync-command))
(println)
(confirm "Does this command look good?")
(p/check (p/process rsync-command {:out :inherit :err :inherit}))
(println)
(println "Backup completed sucessfully")
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