shell-scripts.md

Shell Scripts

Venice allows you to write shell scripts without a hassle. The 'io' functions are pretty powerful when dealing with files. You're not going to miss Unix tools like 'awk, 'sed'.

The REPL let's you interactively run and test commands.

Noticeable Functions

System functions

• os−type, os−type?
• os−arch, os−name, os−version
• system-env
• current−time−millis
• sleep
• host−name, host−address

File I/O

• io/file
• io/file−parent, io/file−name
• io/file−path, io/file−absolute−path, io/file−canonical−path
• io/mkdir, io/mkdirs
• io/slurp, io/slurp−lines, io/spit
• io/copy−file, io/move−file
• io/delete−file, io/delete−file−tree
• io/list−files, io/list−files−glob, io/list−file−tree
• io/exists−file?, io/exists−dir?, io/file−can−read?, io/file−can−write?, io/file−can−execute?
• io/temp−file, io/tmp−dir, io/user−dir, io/user−home−dir
• ...

Zip/Gzip

• io/zip, io/zip−file
• io/zip−list, io/zip−list−entry−names
• io/zip−append, io/zip−remove
• io/unzip, io/unzip−to−dir
• io/unzip−first, io/unzip−all
• io/gzip, io/gzip−to−stream
• io/ungzip, io/ungzip−to−stream

Web download

• io/download
• io/internet−avail?

Executing shell commands

The sh function is the swiss army knife to deal with the native processes of the underlying operating system (see the Venice cheatsheet for details).

(sh "kill" "-9" 56789 :throw-ex true)

;; printing 
(println (sh "ls" "-l"))
(sh "ls" "-l" :out-fn println :err-fn println)

;; run background process
(println (sh "/bin/sh" "-c" "sleep 30 >/dev/null 2>&1 &")) 
(println (sh "/bin/sh" "-c" "nohup sleep 30 >/dev/null 2>&1 &"))

;; working directory
(println (with-sh-dir "/tmp" (sh "ls" "-l") (sh "pwd")))
(println (sh "pwd" :dir "/tmp"))

;; list files in a directory with a glob pattern
(->> (io/list-files-glob "." "*.png")
     (docoll println))

Shell Extension Module

The Shell Extension Module offers OS agnostic functions to manage processes or open files with the platform specific application.

Utils

• shell/open
• shell/open-macos-app
• shell/diff

Processes

• shell/alive?
• shell/process-handle
• shell/process-info
• shell/current-process
• shell/pid
• shell/processes
• shell/parent-process
• shell/descendant-processes
• shell/kill, shell/kill-forcibly
• shell/wait-for-process-exit

For details see: The Shell Extension Module

Example

A larger example that zips Tomcat log files

;; -------------------------------------------------------------------------------
;; Zips the last month's Tomcat log files
;;
;; > java -jar venice-1.10.11.jar -file zip-tomcat-logs.venice ./logs
;; -------------------------------------------------------------------------------
(do
   (defn tomcat-log-file-filter [prefix year month]
     (let [regex (str/format "%s[.]%d-%02d-[0-9][0-9][.]log" prefix year month)]
       (fn [f] (match? (io/file-name f) regex))))

   (defn tomcat-log-file-zip [prefix dir year month]
     (io/file dir (str/format "%s.%d-%02d.zip" prefix year month)))

   (defn zip-files [dir zip files]
     (with-sh-throw
        (with-sh-dir dir
           (apply sh (concat ["zip" (:name zip)] (map #(:name %) files))))))

   (defn zip-tomcat-logs [prefix dir year month]
     (try
        (let [zip (tomcat-log-file-zip prefix dir year month)
              filter (tomcat-log-file-filter prefix year month)
              logs (io/list-files dir filter)]
           (printf "Compacting %s ...\n" prefix)
           (printf "   Found %d log files\n" (count logs))
           (when-not (empty? logs)
              (zip-files dir zip logs)
              (printf "   Zipped to %s\n" (:name zip))
              (apply io/delete-file logs)
              (printf "   Removed %d files\n" (count logs))))
        (catch :com.github.jlangch.venice.ShellException ex
           (printf "Error compacting %s: %s" prefix (:message ex)))))

   (defn first-day-of-month [offset]
     (-> (time/local-date) 
         (time/first-day-of-month) 
         (time/plus :month offset)))

   (let [dir (io/file (nth *ARGV* 2))
         date (first-day-of-month -1)
         year (time/year date)
         month (time/month date)]
      (if (io/exists-dir? dir)
         (do
            (printf "Compacting %d-%02d logs from '%s' ...\n" year month dir)
            (zip-tomcat-logs "localhost_access_log" dir year month)
            (zip-tomcat-logs "host-manager" dir year month)
            (zip-tomcat-logs "manager" dir year month)
            (zip-tomcat-logs "localhost" dir year month)
            (zip-tomcat-logs "catalina" dir year month)
            (println "Done."))
         (printf "Error: The Tomcat log dir '%s' does not exist" dir))))