Created: 2011-07-15 11:41
Updated: 2019-02-23 04:21
License: mit


Shadowspawn is no longer under active development. I still run it every night on my machine, so it works fine, but I'm not planning on doing any additional coding on it. You are welcome to download and use it, and I still make an attempt to help people who are having problems with it.

You are welcome to fork the project. The license (MIT) is very permissive. Indeed, if you have any interest in taking over development, give me a shout: I'd be happy to redirect people to a more actively-maintained fork.

What Is ShadowSpawn?

ShadowSpawn is a tool for working with shadow copies. Shadow copies are read-only snapshots of your disk. Working with shadow copies instead of the actual files allows you to do things like work with in-use (locked) files.

ShadowSpawn works by making a shadow copy of your disk, making it available at a drive letter, then launching (spawning) another program that you specify.

Probably the most common way to use ShadowSpawn is to use Robocopy make a copy of files that are currently in use.

Installing ShadowSpawn

Most users can simply unzip the appropriate zip file from the download page. ShadowSpawn.exe can then just be run - there is no installer. However, ShadowSpawn uses the Visual C++ runtime, which may not be present on some machines. If ShadowSpawn does not work for you, run the vcredist executable available from the same download page.

Running ShadowSpawn

ShadowSpawn is a command-line tool: there is no GUI.

ShadowSpawn take three arguments:

  1. The directory that contains the files you want to snapshot.
  2. An available drive letter where the snapshot will become visible.
  3. A command to run.

Let's say that you wanted to use robocopy to copy files from the C:\foo directory to the C:\bar directory. You could do that with the following command:

shadowspawn C:\foo Q: robocopy Q:\ C:\bar /s

That would cause shadowspawn to

  1. Make a shadow copy of the C: drive.
  2. Mount the shadowed version of the C:\foo directory at Q:.
  3. Launch robocopy Q:\ C:\bar /s
  4. Wait for Robocopy to finish.
  5. Clean up the shadow copy and remove it from Q:

You can use any drive letter you want (it doesn't have to be Q:), but it does have to be a drive letter that's not currently being used for anything else.

You can run any command you want. So if you just wanted to use notepad to look at a shadow copy of C:\foo\blah.txt, you'd run

shadowspawn C:\foo Q: notepad Q:\blah.txt

Just remember that shadowspawn will remove the Q: drive as soon as the command you specify exits.

Relationship to HoboCopy

ShadowSpawn is derived from the same source code as HoboCopy and is intended to replace it. The evolution was driven by the fact that although the shadow copy part of HoboCopy works well enough, the copying part was nowhere near as robust as tools like RoboCopy. By providing a tool that just takes care of the shadow copy, ShadowSpawn allows users to work with locked and in-use files using any other tool, not just the limited copy features provided by HoboCopy.


ShadowSpawn is currently at version 0.1.0, which is meant to indicate that it is an initial version. While it largely consists of fairly mature code taken from HoboCopy, there are bound to be a few issues as early adopters identify opportunities for improvement.

Reporting Bugs and Requesting Features

Please report bugs and request features using either the project issue tracking system or the project mailing list at (website).



shadowspawn [ /verbosity=LEVEL ] <src> <drive:> <command> [ <arg> ... ]

Creates a shadow copy of <src>, mounts it at <drive:> and runs <command>.

/verbosity   - Specifies how much information ShadowSpawn will emit
               during execution. Legal values are: 0 - almost no
               information will be emitted. 1 - Only error information
               will be emitted. 2 - Errors and warnings will be
               emitted. 3 - Errors, warnings, and some status
               information will be emitted. 4 - Lots of diagnostic
               information will be emitted. The default level is 2.

<src>        - The directory to shadow copy (the source directory).
<drive:>     - Where to mount the shadow copy. Must be a single letter
               followed by a colon. E.g. 'X:'. The drive letter must be
               available (i.e. nothing else mounted there).
<command>    - A command to run. ShadowSpawn will ensure that <src> is
               mounted at <drive:> before starting <command>, and will
               wait for <command> to finish before unmounting <drive:>

Exit Status:

If there is an error while processing (e.g. ShadowSpawn fails to
create the shadow copy), ShadowSpawn exits with status 1.

If there is an error in usage (i.e. the user specifies an unknown
option), ShadowSpawn exits with status 2.

If everything else executes as expected and <command> exits with
status zero, ShadowSpawn also exits with status 0.

If everything else executes as expected and <command> exits with a
nonzero status code n, ShadowSpawn exits with status n logically OR'ed
with 32768 (0x8000). For example, robocopy exits with status 1 when
one or more files are Scopied. So, when executing

  shadowspawn C:\foo X: robocopy X:\ C:\path\to\backup /mir

the exit code of ShadowSpawn would be 32769 (0x8000 | 0x1).
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