I regularly need some scripts for copying files to folders or remote servers, for creating folders, checking file existence, etc. The scripts should also be able to accept parameters. Often I try to write a bash script for these tasks, but it always takes much longer than expected. Similarly, on Windows, I do the same with batch/cmd-files, whose syntax is not much better to remember than bash.
I will not do this anymore, it is too cumbersome for me!
From now on, I will use a language I know very well: JavaScript!. Might sound strange but it is actually quite easy. I use
node.js as "interpreter" and call the OS functions via the
child_process or
fs modules. Esp. error checking is much more versatile now!
Combine that with
CoffeeScript, and take shell/batch-scripting tasks to the next level, including easy async. task execution with callbacks! Thanks to CoffeeScript, I get rid of the bad parts of JavaScript. Here is a simple copy script as example (replace the echo cmd with a copy command of your choice)
fs = require("fs")
exec = require("child_process").exec
files = process.argv.slice 2
target = files.pop()
stop_onerror = true
error_count = 0
copy_next = ->
if files.length == 0 then stop()
else
file = files.pop()
exec "echo copying #{file} to #{target}", (error, out) ->
console.log out.trim()
if error?
console.error "ERROR(#{error_count++})! copy of #{file} failed"
if error? && stop_onerror then stop() else copy_next()
stop = ->
if error_count > 0
console.log "Files copied (with #{error_count} errors)."
else
console.log "All files copied successfully."
usage = -> console.log '''
Usage (with node)
node script.js file1 file2 file3 ... target
Usage (with coffee)
coffee script.coffee file1 file2 file3 ... target
'''
if files.length > 0 && target? then fs.stat target, (error, fstat) ->
if error? then console.log "#{target} not found!"
else console.log "copying #{files} to #{target}"; copy_next()
else usage()
This basic script just mimics a normal copy command and is therefore rather useless. But it shows that you can easily combine node.js' file-system functions with operating system calls via
exec, and that it is really easy to add more features, such as automatic target-dir creation, file-renames, error logging, etc. Esp. such error checking and other conditional stuff is really cumbersome in plain bash/batch scripting.
Ciao,
Juve
