rwd

Warns if the process has been started with the wrong cwd

npm install rwd
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rwd

Warns if the process has been started with the wrong cwd

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rwd means real working directory.
Global modules don't need the rwd module.

Did you know why the people prefix __dirname before a path?

var fs = require ("fs");
fs.existsSync (__dirname + "/file");

It's because the process.cwd() function returns the shell's current working directory instead of the directory where lives the main script of your application.

Look at this example:

$ pwd
/home/user1
$ mkdir dir
$ cat > dir/app.js
console.log (process.cwd ());
$ node dir/app.js
/home/user1
$ cd dir && node app.js
/home/user1/dir

If you execute the main script with a relative path like the above example ($ node dir/app.js), very bad things could happen and it's nearly impossible to detect why your code is not working as expected. This is a feature found on all the programming languages because it's a thing related with the OS, not with the programming language itself.

$ node dir/app behaves different than $ cd dir && node app.

The following example illustrates a very ingenuous script, but depending on how you execute it, very dangerous things could happen:

//$ node dir/app.js
var fs = require ("fs");
if (fs.existsSync ("settings.json")){
    doSomethingUseful ();
}else{
    //Warning!!
    saveToDatabaseDefaultSettings ();
}

This can be easily fixed changing the cwd at runtime, but it's discouraged. The best way to ensure that the application is started correctly is to require the rwd module. I recommend to put it in the very first line of your main file:

//app.js
require ("rwd");

The module is automatically uncached.

Then, if you start the process with a relative path, eg: $ node dir/app.js, a message will be printed and the process will exit with code 1, something similar to this:

The process has been started this way:

  $ node dir/app.js

Better alternatives:

  $ cd dir && node app.js
  $ node <absolute_path>/dir/app.js

This way, you don't need to prefix the paths with __dirname because if the process doesn't finish this means that the cwd is the same as the directory of the main file.

Alternatives

For your convenience you can create a global variable similar to __dirname which can be used safely from any module (__dirname is local to the file). For example, you can run this snippet in the main file:

var path = require ("path");
global.__root = path.dirname (process.mainModule.filename);

Then, every time you need to use a relative path from the root, you can prefix it with __root:

var fs = require ("fs");
if (fs.existsSync (__root + "/settings.json")){
    doSomethingUseful ();
}
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