function escapeStringPosix(str)
        {
            function escapeCharacter(x)
            {
                var code = x.charCodeAt(0);
                if (code < 256) {
                    // Add leading zero when needed to not care about the next character.
                    return code < 16 ? "\\x0" + code.toString(16) : "\\x" + code.toString(16);
                 }
                 code = code.toString(16);
                 return "\\u" + ("0000" + code).substr(code.length, 4);
             }

            if (/[^\x20-\x7E]|\'/.test(str)) {
                // Use ANSI-C quoting syntax.
                return "$\'" + str.replace(/\\/g, "\\\\")
                                  .replace(/\'/g, "\\\'")
                                  .replace(/\n/g, "\\n")
                                  .replace(/\r/g, "\\r")
                                  .replace(/[^\x20-\x7E]/g, escapeCharacter) + "'";
            } else {
                // Use single quote syntax.
                return "'" + str + "'";
            }
        }
@param {!WebInspector.NetworkRequest} request
@return {string}