CurlCookies

ExportCurlCookies.js

var sys = require("system"), fs = require("fs");
if(sys.args.length < 2)
{
    console.log("ExportCurlCookies requires a parameter - cookie file name.");
    phantom.exit(1);
}

var Dest = sys.args[1];
var f = fs.open(Dest, {mode:"w"});

f.writeLine("# Netscape HTTP Cookie File");
f.writeLine("# http://curl.haxx.se/docs/http-cookies.html");
f.writeLine("# This file was generated by libcurl! Edit at your own risk.");
f.writeLine("");

var i, n = phantom.cookies.length;
for(i=0;i<n;i++)
{
    var Coo = phantom.cookies[i];
    f.writeLine(
        (Coo.httponly ? "#HttpOnly_" : "") + Coo.domain + "\t" +
        (Coo.domain.substr(0, 1) == "." ? "TRUE\t" : "FALSE\t") +
        Coo.path + "\t" +
        (Coo.secure ? "TRUE\t" : "FALSE\t") + 
        Coo.expiry.toString() + "\t" +
        Coo.name + "\t" +
        Coo.value
    );
}
f.close();
phantom.exit(0);

ImportCurlCookies.js

var sys = require("system"), fs = require("fs");
if(sys.args.length < 2)
{
    console.log("ImportCurlCookies requires a parameter - cookie file name.");
    phantom.exit(1);
}
var Src = sys.args[1];
if(!fs.isFile(Src))
{
    console.log("Source file " + Src + " not found.");
    phantom.exit(1);
}

Src = fs.read(Src, {mode:"r"}).split("\n");
var i, n = Src.length;
for(i=0;i<n;i++)
{
    var l = Src[i].trim();
    if(l.length && (l.substr(0, 1) != "#" || l.substr(0, 10) == "#HttpOnly_"))
    {
        var a = l.split("\t");
        var HttpOnly = a[0].substr(0, 10) == "#HttpOnly_";
        var Domain = HttpOnly ? a[0].substr(10) : a[0];
        if(Domain.substr(0, 1) != ".")
            Domain = "." + Domain;
        var Expires  = parseInt(a[4]) * 1000;
        if(!Expires)
            Expires = undefined;        
        if(phantom.addCookie(
            {
                name: a[5],
                value: a[6],
                domain: Domain,
                path: a[2],
                httponly: HttpOnly, 
                secure: a[3] == "TRUE",
                expires: Expires 
            }))
        {
            console.log("Added " + a[5] + "@" + Domain);
        }
        else
        {
            console.log("Error adding " + a[5] + "@" + Domain);
        }
    }
}

phantom.exit(0);

Translating cookie files from PhantomJS format to cURL format and back.

The command line for PhantomJS to cURL conversion goes:
phantomjs --cookies-file=src.txt ExportCurlCookies.js dest.txt
And the command line for other way would go:
phantomjs --cookies-file=dest.txt ImportCurlCookies.js src.txt

The export script overwrites the destination file completely, doesn't add to it. The import script merges the file contents with the existing cookies.

Tested against PhantomJS 1.9.8.