Create relative symlinks using absolute paths in Node.JS

Question

I have a projects with the following structure:

project-root
├── some-dir
│   ├── alice.json
│   ├── bob.json
│   └── dave.json
└── ...

I want to create symlinks like the following ones:

• foo -> alice.json

I chose to use the fs.symlink function:

fs.symlink(srcpath, dstpath[, type], callback)

Asynchronous symlink(2). No arguments other than a possible exception are given to the completion callback. The type argument can be set to 'dir', 'file', or 'junction' (default is 'file') and is only available on Windows (ignored on other platforms). Note that Windows junction points require the destination path to be absolute. When using 'junction', the destination argument will automatically be normalized to absolute path.

So, I did:

require("fs").symlink(
  projectRoot + "/some-dir/alice.json"
, projectRoot + "/some-dir/foo"
, function (err) { console.log(err || "Done."); }
);

This creates the foo symlink. However, since the paths are absolute the symlink uses absolute path as well.

How can I make the symlink path relative to a directory (in this case to some-dir)?

This will prevent errors when the parent directories are renamed or the project is moved on another machine.

The dirty alternative I see is using exec("ln -s alice.json foo", { cwd: pathToSomeDir }, callback);, but I would like to avoid that and use the NodeJS API.

So, how can I make relative symlinks using absolute paths in NodeJS?

Answer 1

Option 1: Use process.chdir() to change the current working directory of the process to projectRoot. Then, provide relative paths to fs.symlink().

Option 2: Use path.relative() or otherwise generate the relative path between your symlink and its target. Pass that relative path as the first argument to fs.symlink() while providing an absolute path for the second argument. For example:

var relativePath = path.relative('/some-dir', '/some-dir/alice.json');
fs.symlink(relativePath, '/some-dir/foo', callback);

Answer 2

const path = require('path');
const fs = require('fs');

// The actual symlink entity in the file system
const source = /* absolute path of source */;

// Where the symlink should point to
const absolute_target = /* absolute path of target */;

const target = path.relative(
    path.dirname(source),
    absolute_target
);

fs.symlink(
    target,   
    source,
    (err) => {

    }
);