fs-admin

Perform file system operations with administrator privileges.

Installing

npm install fs-admin

Packaging (Linux only)

This library uses PolicyKit to escalate privileges when calling createWriteStream(path) on Linux. In particular, it will invoke pkexec dd of=path to stream the desired bytes into the specified location.

PolicyKit

Not all Linux distros may include PolicyKit as part of their standard installation. As such, it is recommended to make it an explicit dependency of your application package. The following is an example Debian control file that requires policykit-1 to be installed as part of my-application:

Package: my-application
Version: 1.0.0
Depends: policykit-1

Policies

When using this library as part of a Linux application, you may want to install a Policy as well. Although not mandatory, policy files allow customizing the behavior of pkexec by e.g., displaying a custom password prompt or retaining admin privileges for a short period of time:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE policyconfig PUBLIC
 "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/PolicyKit/1.0/policyconfig.dtd">
<policyconfig>
  <vendor>Your Application Name</vendor>
  <action id="my-application.pkexec.dd">
    <description gettext-domain="my-application">Admin privileges required</description>
    <message gettext-domain="my-application">Please enter your password to save this file</message>
    <annotate key="org.freedesktop.policykit.exec.path">/bin/dd</annotate>
    <annotate key="org.freedesktop.policykit.exec.allow_gui">true</annotate>
    <defaults>
      <allow_any>auth_admin_keep</allow_any>
      <allow_inactive>auth_admin_keep</allow_inactive>
      <allow_active>auth_admin_keep</allow_active>
    </defaults>
  </action>
</policyconfig>

Policy files should be installed in /usr/share/polkit-1/actions as part of your application's installation script.

For more information, you can find a complete example of requiring PolicyKit and distributing policy files in the Atom repository.