Link Shell Extension (original) (raw)

Last Updated December 18 2022, Version 3.9.3.5

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Introduction

The NTFS file system supports a facility known as hard links (referred to herein as Hardlinks). Hardlinks provide the ability to keep a single copy of a file yet have it appear in multiple folders (directories). They can be created with the POSIX command ln included in the Windows Resource Kit, the fsutil command utility included in Windows or my command lineln.exe utility. Thus, using standard Windows facilities Hardlinks can only be created at the command prompt, which can be tedious, especially when Hardlinks to multiple files are required or when one only makes occasional use of Hardlinks.

Support for Junctions in standard Microsoft software offerings is even more limited than that offered for hardlinks.
Recently Winfile.exe was github-reborn by Microsoft, and I spent quite some time to make it hardlink and symbolic link aware. For easy tasks you might try Winfile

Link Shell Extension (LSE) provides for the creation ofHardlinks, Junctions,Volume Mountpoints, and Symbolic Links, (herein referred to collectively as Links) a folder cloning process that utilises Hardlinks or Symbolic Links and a copy process taking care of Junctions, Symbolic Links, and Hardlinks. LSE, as its name implies is implemented as a Shell extension and is accessed from Windows Explorer, or similar file/folder managers.
The extension allows the user to select one or many files or folders, then using the mouse, complete the creation of the required Links - Hardlinks, Junctions or Symbolic Links or in the case of folders to create Clones consisting of Hard or Symbolic Links. LSE is supported on all Windows versions that support NTFS, Windows7/8/10. Hardlinks, Junctions and Symbolic Links are NOT supported on FAT file systems, and nor is the Cloning and Smart Copy process supported on FAT file systems.

Within this document the terms action button and action (pop up) menu are used to refer what are often referred to as the right mouse button and the pop up menu that is displayed when that mouse button is pressed (often referred to as the context menu). Recognising that people swap the usage of their mouse buttons, Microsoft refer to the primary and secondary mouse buttons. We prefer to refer the mouse buttons as theSelect button and the Action button; and rather than terms such as Context Menu, Shell Menu, Right Mouse Menu we use the term Action menu.

Installation

The current user must have administrator privileges in order to install the software.

LSE is installed by executing the install program(HardLinkShellExt_$(platform).exe). Follow the instructions issued by the program, there are no mandatory inputs required during installation. It is possible to change the location into which LSE is installed, the default is

C:\Program Files\LinkShellExtension

Smartscreen pop-up
With Windows 10 the SmartScreen facility of Windows Defender might pop up and warn you:

Windows protected your PC Windows Defender SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk.

Please choose 'Install Anyway'. LSE is signed with a Standard Code Signing Certificate, but not with anEV Code Signing certificate, which would prevent Smartscreen from interferring.

Explorer Restart
During installation Explorer.exe has to be restarted to make Link Shell Extension active. This means that all pending operations with explorer.exe are interrupted but with the interactive install you can decide to postpone the explorer.exe restart. A dialog box will give you the choices during installation.

Installation Arguments

Some command line switches can be passed during install, so that a silent install via .bat file can be acchieved.

Silent install
/S pops up no prompts during install. If the /S switch is used, explorer.exe will be restarted after installation, to make Link Shell Extension active immediately.

Specify Language
/LANGUAGE passes the language in which LSE shows up. e.g.

HardLinkShellExt_$(platform).exe /S /Language=English Currently English, Chinese, Czech, French, German, Greek, Italian, Japanese, Korean, Polish, Portuguese, Russian, Slovak, Spanish, Swedish, Turkish and Ukrainian are available as valid parameters for the /Language switch.

Specify Directory
When using the silent install a directory can also be specified with the /D switch e.g.

HardLinkShellExt_$(platform).exe /S /Language=English /D=C:\Program Files\LSE

Uninstall
Link Shell Extension can also be uninstalled silently by issuing

$LSEInstallDir/uninst-HardLinkShellExt_$(platform).exe /S

If the /S switch is used during uninstall, explorer.exe will be restarted after uninstallation, to make Link Shell Extension inactive immediately.

No Check for VcRedist
On some Windows10 machines, there is no need to install the vcredist, or worse: VcRedist can not be installed, but is somehow already on the system. To overcome this the /noredist switch can be passed via command line. e.g.:

HardLinkShellExt_$(platform).exe /noredist

Chocolatey Installation

Link ShellExtension can also be installed via chocolatey by issuing

choco install linkshellextension

from a command prompt. Make sure you have chocolatey installed. The current user must have administrator privileges in order to install the software via choco

Winget Installation

LSE can also be installed via winget by issuing

winget install HermannSchinagl.LinkShellExtension

from a command prompt. Make sure you have winget installed.

Using Link Shell Extension

Pick Link Source causes the selected files to be "stored" as the source for the Hardlinks that you want to create.

To create the Hardlinks a destination folder must be chosen, by clicking the mouse action button on the destination folder a menu will pop up, which will include the entry - Drop HardLink

Choosing Drop HardLink will create the hardlinks in the selected destination folder.

Overlay Icons for Hardlinks
To help distinguish hardlinks folders from normal files, an overlay icon is implemented on hardlinks that shows a red arrow icon under the folder.

Overlay icons for Hardlinks can also be customized.

Cancel current Pick Link operation

When doing an Action button click in the destination folder background, in addition to the Drop HardLink option there is the possibility to Cancel Link Creation entry.

Popup Submenu

Since LSE supports Junction,Clones and Symbolic Links, when one or more folders are selected as the Source, they can be dropped in several ways.

To avoid crowding the popup menu, a submenu is provided that contains the different types of Links applicable to folders.

Drag and Drop Support

Creating Hardlinks via drag and drop is supported, after selecting one or more files you can drag them to the destination folder with the Action button held down; when it is released choose HardLink Here from the action menu to create the Hardlinks of the selected files in the destination folder.

Auto Rename

Files can be hard linked to the same folder as the source folder. Because two directory entries cannot have the same name, LSE uses '$filename - Hardlink.$ext' as the name of the the new link.

LSE uses the same hydraulics as explorer when it comes to multiple '$filename - Hardlink': It uses numbers to enumerate the multiple hardlinks of one file in the same directory, e.g.$filename - Hardlink (2).$ext.

The Auto Rename mechanism is also used when Junctions, Hardlink Clones, Symbolic Links, Symbolic Link Clones, Mountpoints or Smart Copies are created in the same directory.

Junction Support

Junctions provide for the creation of linkages among directories.

Junctions are created in the same way as Hardlinks, except that the Source Link is a folder rather than a file. Select a folder, click the right mouse button, choosePick Link Source from the action menu, navigate to the destination folder, click the action button, open the submenu Drop As ... and select Junction:

Junctions are marked with a small piece of chain below the folder icon.

Junctions can also be created via Drag and Drop when the selected folders are dragged with the action button pressed to a destination folder; when the right mouse button is released, select theDrop Here ... submenu and then Junction.

Overlay Icons for Junctions
To help distinguish junction folders from normal folders, an overlay icon is implemented on junctions that shows a small three link chain icon under the folder.

Overlay icons for junctions can also be customized.

Junctions can span network drives as long as the target is a mapped network drive. Unfortunately Junctions, which have a UNC Path as target, can be created with LSE, but even Windows7/8/10 seems to contain a bug, which prevents it from dereferencing a UNC Path in a junction, even if LSE correctly sets up the reparse info for UNC junctions. When a UNC target junction is double clicked in explorer the error ERROR_INVALID_REPARSE_DATA(4392), will show up and tell you that the info in the reparse point is illegal, even if it is not.

Elevation is needed in e.g. c:\Program Files for junctions beeing created in. This is why the famous UAC dialog must be acknowledged.
To be exact: Only the creation of directories needs elevation in such situations, but creating an empty directory is a vital part of creating a junction. The DeviceIoControl(), which does the real work in creating junctions would work without elevation.

Replacement Junction Symbolic Link Mountpoint

Link Shell Extension can change the target of an existing Junction, Symbolic Link or MountPoint either via Pick/Drop or Drag and Drop.

To use this feature simply select an existing directory as Link Source and drop it over an already existing Junction/Symbolic Link/Mountpoint. By selecting the 'Drop as ... Replacement Junction/Symbolic Link/MountPoint' from the action menu, the target of an already existing Junction/Symbolic Link/MountPoint is replaced by the newly picked target.

The same can be achieved via Drag an Drop for Symbolic Link Directories, Junctions and Mount Points, but not for Symbolic Link Files. Symbolic Link Files have to be repaired by the 'Pick Link Source', 'Drop as ... Replacement Symbolic Link' repair alternative.

When the backup mode is selected the ACLs of the Junction/Symbolic Link/MountPoint are preserved.

Copy Junction Symbolic Link Mountpoint

Link Shell Extension can copy an existing Junction, Symbolic Link or MountPoint either via Pick/Drop or Drag and Drop.

To use this feature simply select an existing Junction, Symbolic Link or MountPoint as Link Source and drop it over an already existing directory. By selecting the 'Drop as ... Junction/Symbolic Link/MountPoint Copy' from the action menu, the Junction/Symbolic Link/MountPoint is copied to the target and the relation is adjusted

The same can be achieved via Drag an Drop for Symbolic Link Directories, Junctions and Mount Points.

When the backup mode is selected the ACLs of the Junction/Symbolic Link/MountPoint are preserved.

Smart Copy

Smart Copy creates a copy of the directory structure from the source location to the destination, but it preserves the inner hardlink structure and inner junction/symbolic link relations of the source, and recreates this inner hardlink structure and inner junction/symbolic link relation at the destination location:

With hardlinks it behaves as follows:

By closely looking at the above picture one can find three different types of files:

With junctions or symbolic link directories the default behaviour during smartcopy is as follows:

By closely looking at the above picture one can find three different types of folders/junctions:

Windows7/8/10 support Symbolic Links, which behave as follows during Smart Copy:

By closely looking at the above picture one can find three different types of files/symbolic links:

Smart Copies are created in the same way as Junctions, select a folder, click the Action button, choose Pick Link Source from the action menu...

...navigate to the destination folder, press the action button, open the Drop As ... submenu and select Smart Copy:

Smart Copy is a must if e.g.. the whole content of a hard disk, which has lots of hardlinks/junctions/symbolic links, should be copied to another hard disk. During the Smart Copy operation empty folders get copied too and the date/time stamps of folders/junctions/symbolic links are also restored at the corresponding destination locations.

Because Smart Copy creates inner hardlinks/junctions/symbolic links, this feature is only available on NTFS volumes.

If Smart Copy takes longer than 250msec a progressbar shows the status of the smart copy operation.

Smart Copy also processes all available alternative NTFS streams of a file.

If items are already available in the destination, Smart Copy only copies when the Files/Symbolic/Junctions/MountPoints are newer than the already existing items.

When restoring Symbolic links LSE forks its helper LSEUacHelper.exe to forwards this operation to it, because the creation of symbolic links needs elevation, and thus brings up the famous UAC dialog.

LSE only issues its helper LSEUacHelper.exe if a symlink is among/below the selected folders, so it saves you from one UAC prompt if you don't have symlinks among your selection.

Smart Copy by default creates relative symbolic links during the Smart Copy operation.

Command LineThe Smart Copy functionality is also available via command line fromn.exe via the --copy command line switch.

Crop/Unroll/Splice Outer Junctions/ Symbolic Links

During SmartCopy, Smart Mirror, Delorean Copy and Clone so called Outer Junctions/Symlink directories may need processing. There are 3 different ways to deal with those Outer Junctions/Symlink directories:

Crop	Crop breaks links to Outer Junctions/Symlink directories in the destination. Crop also applies to Outer Symlink Files. In the above example Folder1 is copied to Destination/Folder1, but_Outer Junction/Symlink_ is not available in the destination, because Folder1/Outer Junction/Symlink pointed to Folder0/Outer Junction/Symlink Target, which is not below Folder1. The objective behind cropping Outer Junctions/Symlink Directories is to get a pure copy during Smart Copy, Smart Mirror, Delorean Copy and Clone without connections to the source. Enabling Crop for Outer Junction/Symbolic Links Crop can be selected via the configuration tool.
Unroll	Unroll follows Outer Junctions/Symlink Directories and rebuilds the content of Outer Junctions/Symlink Directories inside the hierarchy at the destination location. Unroll also applies to Outer Symlink Files, which means, that unroll causes the target of Outer Symlink Files to be copied to the destination location. In the above example Folder1 is copied to Destination/Folder1, and_Outer Junction/Symlink_ and all the files/directories below_Outer Junction/Symlink Target_ are copied to the folder Outer Junction/Symlink in the destination. The objective behind unrolling Outer Junctions/Symlink Directories is to get everything with which the source is connected and rebuild it as seperate copy in the destination. It resembles the 'hair of the elephant' pattern: Pull on a hair of an elephant, and get the whole elephant. Unroll is the default behaviour for Smart Copy, Smart Mirror, Delorean Copy and Clone. Advanced thoughts on Unrolling The picture above was just the simplest case, because Unroll does much more when it encounters complex situations. Think of an outer junctions/symbolic links, which itself contains junctions/symbolic links, which are inner with respect to the first outer junction symbolic link: In the above example Folder1 is copied to Destination/Folder1, and_Outer Junction/Symlink_ and is unrolled as expected, but since Junction/Symlink is an inner junction with respect to Outer Junction/Symlink Target, the junction/symlink relation is restored in the destination. This kind of nesting can be much more complex: In the above example Folder1 is copied to Destination/Folder1, and_Outer Junction/Symlink_ and is unrolled as expected, but then it starts to get fascinating, because we have two levels of outer junctions/symlinks which all have respective inner junctions/symlinks, and which are restored properly. Once you digged yourself through the above picture, you got it. It is not simple I know, but it is necessary to properly unroll. And complexity increases if symbolic link files are within unrolled outer junctions/symbolic links: In the above example Folder1 is copied to Destination/Folder1, and_Outer Junction/Symlink_ and is unrolled as expected, but it contains Inner Outer Symlink which points to Inner Outer Symlink Target and this is an inner junction/symbolic link with respect to Outer Junction/Symlink Target But worth mentioning is the Symbolic Link Outer Symlink, which would be a definitive outer symbolic link, but since its targets parent-directory Outer Junction/Symlink Target is unrolled,Outer Symlink becomes an inner symbolic link with respect to Folder1. File1 Symlink is also an outer symbolic link, but its target parent-directory_Folder2_ is not that lucky to get unrolled, so in the destination File1 Symlink is not a symbolic link any more, but a copy of the symbolic links' target. Nested Reparse Points are also an interesting use case, which the algorithm has to tackle with: In the above example Folder1 is copied to Destination, and_Junction/Symlink F0_ and is unrolled as expected, but it contains inner nested reparse points. Nested means Reparse Points pointing to Reparse Points The Unroll functionality also opens up the possibility to have circular Junction/Symbolic Link relations among a set of copied items: In the above example Folder1 is copied via the --unroll option to Destination/Folder1. Smart Copy/Smart Mirror and Delorean Copy operations can deal with the above shown circularities and break circularities by not following the affected Junction/Symbolic Link. Junctions/Symbolic Links can also point to FAT drives or other NTFS drives requiring as a prerequisite unique Disk-IDs on all disks, which are chained together via Junctions/Symbolic links: Hardlink siblings are found by matching the per NTFS volume uniqe file-id, but if more volumes are chained together it might happen that the same file-ids can be found on two different NTFS volumes. To address this all operations use the disk-id and the file-id to match hardlink siblings. Furthermore it is not allowed to have the disk-id 0xffff-ffff, because the algorithms use this as internal indicator of a FAT drive. The Unroll option also allows to point multpile junctions to the same target location, which causes the algorithms to traverse the same items many times: At the first glance multiple traversation of items looks simple, but for files this means that multiple traversed files are the same in the destination and are hardlinked together. So don't be confused when you see hardlinks, which have never ever been there before. Copying Junction/Symbolic Links from mapped network drives also needs extra care, because junctions on the remote machine relate with path references only valid on the remote machine to each other: The example in the above picture shows such a situation X:\Src\Foo\Junction/Symlink is a junction on a Remote Machine, which points to X:\Src\Foo\Folder. It is a valid Junction. X:\Src\Foo is sharded via \\RemoteMachine\MyShare, which still is no problem. \\RemoteMachine\MyShare mapped to T:\ on a local machine is fine, but the Junction T:\Junction/Symlink, if asked for its target, will still return X:\Src\Foo\Folder even on the Local Machine. One could expect that the target is T:\Folder, but it is not for Junctions. When SmartCopy/Mirror/Delorean comes across such a situation, it translates the Junction correctly when it is copied onto the Local Machines drive Y:\, so that the final Junction target points correctly to Y:\Dest\Bar\Folder
Splice	Splice reconnects Outer Junctions/Symlink directories in the destination to their original targets. In the above example Folder1 is copied to Destination/Folder1, and_Outer Junction/Symlink_ is available in the destination as junction, which points to the original location Outer Junction/Symlink Target. The objective behind splicing Outer Junctions/Symlink Directories to its original location is to get a copy during smartcopy, but to reuse Outer Junctions/Symlink Directories source locations. The Splice functionality is also useful, when mountpoints should be copied. Mountpoints are very similar to Junctions, but point to a path always starting with \\?\VolumeGuid{}. Enabling Splice for Outer Junction/Symbolic Links Splice can be selected via the configuration tool.

Multiple Source

Multpiple Source Locations can be specified for SmartCopy, Clone, and Delorean Copy. If there are junctions/symlinks between these source locations, they are handled as inner junctions/symbolic links, because all source locations are dealt like a common root.

In the above example Location1 and Location2 are copied to Destination.Location2/Junction20 is treated as inner junctions to Location1/Folder10 in the source, and that's why Destination/Junction20 points to Destination/Folder10 in the Destination.

The objective behind this is to treat all junctions/symlinks as inner junctions/symlins as long as they are in the set of source folders.

With LinkShell Extension this works as follows:

In the above example all content from Location 1 and Location 2 and pskill.exe are selected. Possible junctions/symbolic links in Location 1 pointing to Location 2 or vice versa are treated as inner junctions/symbolic links, because all selection is treated as a common root.

Smart Move

Smart Move enables folders with junctions and symbolic links beneath to be renamed. The junctions and symbolic links' targets are updated below that folder. Without Smart Move renaming of such folders would end in dead junctions and symbolic links.

With junctions or symbolic link directories it behaves as follows:

By closely looking at the above picture one can find three different types of folders/junctions:

The Smart Move functionality is integrated into Explorer seamlessly, so that you don't have to do anything special. Simply drag a folder in explorer to its destination location, or e.g. press F2 in Explorer to rename a directory and LSE will intercept this operation under the hood, takes care of junctions or symbolic links, and will update them.

Intercepting move and rename operation means, that LSE takes over control before rename/move, and recursivley searches the selected folder for junctions or symbolic links. But searching large amounts of files and folders takes time, so LSE will show a progress bar when searching takes longer than 250msec.

If symbolic links have to be updated LSE calls its UAC helper LSEUacHelper.exe.

If backup mode is enabled the UAC helper LSEUacHelper.exe is called anyway, because LSE needs to enumerate files in locations, where it might have no permissions.

Smart Move creates relative symbolic links during the Smart Move operation.

If a LocalizedResourceName is given via desktop.ini and the very folder is readonly, SmartMove will not work. This seems to be a bug in Shell Explorer ever since. ICopyHook::CopyCallback() is not called at all in this situation.

Enabling/Disabling Smart Move
Smart Move can be switched on/off via the configuration tool

Command Line The Smart Move functionality is also available via command line from ln.exe via the --move command line switch.

Clone

Clones are copies of a folder tree from a source location recreated at the destination location, however the files within the new folder tree are Hardlinks or Symbolic Links to the respective files in the source folder tree.

A folder tree might also contain Junctions or Symbolic Links. The clone process recreates inner junction/symbolic links at the destination location very similar as Smart Copy does.

Outer Junctions/Symbolic links are recreated with respect to the specifiedOuter Junction/Symbolic Link handling. e.g.

With Windows7/8/10 this cloning process is also available with Symbolic Links instead of Hardlinks.

Clones are created in the same way as e.g Junctions. Select a folder, click the Action button, choose Pick Link Source from the action menu...

...navigate to the destination folder, press the action button, open the Drop As ... submenu and select HardLink Clone:

... choose Symbolic Link Clone to create clones of existing tree structures.

HardLink and Symbolic Link Clones can also be created via Drag and Drop. Select a folder and drag with the action button depressed to a destination folder. When the action button is released open the Drop Here... submenu and select HardLink Clone or with Windows7/8/10 Symbolic Link Clone:

HardLink or Symbolic Link Clones are useful if you need to replicate a folder tree at a different location. The disk space required is minimal because the new structure consists entirely of NTFS directory entries with no real amount of actual data storage.

If both files and folders are selected as Source Links and dropped as aHardLink Clone then the selected files are dropped as Hardlinks alongside the HardLink Clones.

Because Clones use Hardlinks or Symbolic Links, they are only available within an NTFS volume. Hardlink Cloning can not replicate the folder structure from one disk volume to a different volume, because Hardlinks are limited to operation on a single volume. Symbolic Link Clones can be used to create volume spanning Clones.

When creating Clones, LSE forks its helper LSEUacHelper.exe to forwards this operation to it, if the folder tree contains symbolic links, because the creation of symbolic links needs elevation, and thus brings up thefamous UAC dialog.
LSE only issues its helper LSEUacHelper.exe if a symlink is among/below the selected folders, so it saves you from one UAC prompt if you don't have symlinks among your selection.

Limitations
Hardlink creation needs write access to the source hardlink sibling. This means Hardlink Clone will fail, and just generates an empty directory structure, if write access for the source files is not available. This is caused in the way Windows implements hardlinks, because the security information for a file and thus for all hardlink siblings is shared among all hardlink siblings.

Creating hardlink clones in such cases can be enabled, by granting write access for the source files to the user who will create a hardlink clone, or in a single user use-case to everyone.

Command Line The Clone functionality via Hardlinks or Symbolic Links is also available via command line from ln.exe via the --recursive command line switch.

Smart Mirror

Smart Mirror is very similar to Smart Copy and not only copies but synchronises the folder Source to Destination:

• Smart Mirror copies if the timestamp of items in the Destination is different from the Source.
• Delete files not anymore available in Source from Destination. Smart Mirror takes care of Hardlink Relations, Restores Inner Junctions or Inner Symbolic links or when issued unrolls or splices Outer Junctions or Outer Symbolic Links.

Smart Mirror is created in the same way as e.g Junctions. Select a folder, click the Action button, choose Pick Link Source from the action menu...

...navigate to the destination folder, press the action button, open the Drop As ... submenu and select Smart Mirror:

Smart Mirror is a little bit different with respect to Auto Rename, because it expects a already existing folder in the destination location, which has the same name as the source folder, so that it can do the mirror.

DeLorean Copy

DeLorean Copy is a way of creating incremental backups by using a combination of hardlink clone and Smart Copy.

The following picture gives an overview what DeLorean Copy is about

In general a DeLorean Copy has 3 principals: Source(t), InitialBackup and Backup(n).

With completion of this first round Backup1 contains the first lean and mean copy of Source only consisting of either hardlinks to InitialBackup, or of copied files if there was the need to copy them over from Source(t+1) because they were newer under Source(t+1).
The point is that all files in Backup1 are transparently accessible, but really little space is used, because not all files in the Source(t+1) changed, so that there was only the need to effectively copy over a few files from Source(t+1) to Backup1.
This can be repeated on and on. The second round would be using Source, Backup1 and Backup2 for DeLorean Copy:

DeLorean Copies are created in the same way as e.g Junctions. Select a folder, click the Action button, choose Pick Link Source from the action menu...

...navigate to the destination folder, press the action button, open the Drop As... submenu and select DeLorean Copy:

If a DeLorean Copy was dropped the first time onto a directory, the operations, which are described under phase 1 in the above descriptions, namely a Smart Copy, is performed. Link Shell Extension automatically generated the folder name for the destination by appending a timestamp.

Any successive drop of a directory onto the a destination directory initates Phase 2 and Phase 3 from the above description, namley it does the Hardlink Clone from the former backup onto the current backup and furthermore does mirror the source onto the current backup.

A directory holding many copies may look like this.

Limitations
It is little known, but NTFS has a limit to create a maximum of 1023 hardlinks to one file. For DeLorean Copy this means that it will display an error message if this limit is exceeded, because exceeding this limit means loss of data among the most recent backup sets:

The reason for exceeding this limit could either be, that there have been more than 1023 backup sets but no hardlinks within the Source, or there are hardlinks within the Source and less than 1023 backup sets.

The DeLorean Copy submenue will not appear if more than one folders are selected as source.

DeLorean Copy is long path safe which means it can handle more than 256 characters in pathes. This is important, because placing a copy with quite long path, but still below 256 characters path length, to destination locations might result in combined path length greater than 256 character. In such a situation no data loss must happen, which Delorean copy guaranties with beeing 'long path safe'. Please make sure that Explorer can not show you the result of such a copy, but the files are there. Alternative explorers like SpeedCommander can handle this.

Command Line DeLorean Copy functionality is also available via ln.exe

Backup Mode

Backup mode enables LSE to also copy ACLs and Encrypted Files from all directories, even the ones without access for the current users.

• LSE always forks its helper process LSEUacHelper.exe, and thus raises theUAC prompt for elevation and password verification. It applies to SmartCopy, SmartMirror, SmartClone, Delorean Copy, SmartMove and Replacement Junction/Symbolic Link/Mountpoint.LSE.exe thus copies
• Alternative Streams on files and folders
• EA Records on files and folders (rarely used)
• Reparse Info
• File Attributes
• Timestamps: Creation Time, Last Access Time, Last Write Time
• Sparse Files and Alternative Sparse Streams
• Encrypted files
• ACLs

Backup Mode is disabled by default, and can be turned on via the LSE configuration tool.

To perform backup operations a user must hold the SE_BACKUP_NAME and SE_RESTORE_NAME privileges. An out of the box Wndows configuration assigns the Backup-Operator and Administrator group these privileges, but additionally the above privileges can be assigned individually to certain users or groups.

Assigning privileges can be accomplished
By gpedit.msc

and navigating to
"Computer Configuration" ->"Windows settings" -> "Security Settings" -> "Local Policies" -> "User Rights Assignments" -> "Backup files and directories"
"Computer Configuration" ->"Windows settings" -> "Security Settings" -> "Local Policies" -> "User Rights Assignments" -> "Restore files and directories"

Without gpedit.msc
Download PolsEdit and add users or groups, who should be able to run backups, to the SE_BACKUP_NAME and SE_RESTORE_NAME privileges.

Volume Mount Point Support

Volume Mountpoints provides functionality to map complete local volumes onto arbitrary disk locations.

Volume Mountpoints are created in the same way as Hardlinks, except that the Source Link is a volume rather than a file. Select a local volume, click the right mouse button, choose Pick Link Source from the action menu, navigate to the destination folder, click the action button, open the submenu Drop As ... and select Volume Mountpoint:

Volume Mountpoints can also be created via Drag and Drop when the selected local volume is dragged with the action button pressed to a destination folder; when the right mouse button is released, select the Drop Here ... submenu and then Volume Mountpoint.

Mount Points can be deleted by using the Unmount Volume command from Explorer as usual.

To show the origin of a Volume Mountpoint, the reference column of a Volume MountPoint shows the volume which is mounted onto the selected path.

Make sure that only local volumes can be mounted but not mapped network drives.

The creation and deletion of Volume Mountpoints is bound to successful elevation, which means that the famous UAC dialog must be acknowledged.

Reference Count

As described in the backgrounders section NTFS maintains a reference count for each data stream object how many NTFS directory entries refer to that objects.

To show the reference counts, a column can be enabled in Explorers right pane by action clicking the Titles row of the details view.

After enabling the reference column the reference count is shown for each file.

Windows7/8/10: The column, which shows the reference count and the origin of the junction is not available, because the way Windows7/8/10 handles user defined columns has been completely revamped by Microsoft and all applications working with so called ColumnHandlers will not work.

Link Properties

Link Shell Extension also supports so called Explorer Property Sheets, which means that if a file or directory property in explorer is opened, Link Shell Extension adds its own tab to show the properties of a hardlink, junction, volume mountpoint or symbolic link.

This additional tab only shows up in the file or directory properties, if the file or directory is a hardlink, junction, volume mountpoint or symbolic link, otherwise this tab is not available.

Explore
For junctions, volume mountpoints or symbolic links this dialog also shows a 'Explore Target' button, which opens an explorer in the specified directory.

Edit
For Junctions, Symbolic Links or Mountpoints the target field can be edited, and after either pressing the Apply button or leaving the Link Property dialog with ok, the changes are applied to the Junction, Symbolic Link or Mountpoint.

If the Backup Mode is enabled, the ACL of the edited Junction, Symbolic Link or Mountpoint is preserved.

SymbolicLinks

LSE supports the creation of symbolic links.

Creating a Symbolic Link is essentially the same as the other Link creation processes. Action click on the selected file(s) and select Pick Link Source(s) from the action menu.

When the destination folder is action clicked the menu contains a Drop As ... submenu, to create a Symbolic Link select SymbolicLink from the submenu. Unlike Hardlinks Symbolic Links can span storage volumes.

If both files and folders are selected as the Source Links and dropped as a Symbolic Link Clone then the selected files are dropped as Symbolic Links alongside newly created Symbolic Link Clone folders.

Symbolic Links can also be created between directories.

Relative versus absolute symbolic link target pathnames
The target of a symbolic link can either be

• a fully qualified path starting at the root of a drive, e.g e:\data\cpp\myfile.txt
• or can be be specified relativeley, e.g ..\..\data\cpp\myfile.txt LSE by default tries to create relative target path names for symbolic links as long as this is possible, e.g the file and its target are on the same logical drive. Having relative symbolic link targets is much smarter especially when the target of links is in the same directory. If a symbolic link and its target are on different drives, LSE uses absolute pathnames.

The configuration tool can switch Link Shell Extension in either relative or absolute mode.

Overlay Icons for Symbolic Links
To help distinguish Symbolic Links from normal files/directories, an overlay icon is implemented on symbolic links that shows a light green arrow icon under the folder.

Overlay icons for Symbolic Links can also be customized.

Enumeration of Hardlinks

Simply select a hardlinked file and selectProperties from the action menu:

The Hardlink Enumeration functionality is also available via command line fromln.exe via the --enum or the --list command line switch.

UAC

Due to UAC some API calls need elevation to administrative level, and this elevation must be acknowledged via the below shown dialog box. So if you see the below box, and the program asking for elevation is LSEUacHelper.exe, it is Link Shell Extensions contribution to UAC and you must acknowledge it to get Symbolic Links created.

Change Symbolic Link Privilege

One way to come around the UAC prompt for the creation of Symbolic Links is to globally allow users to create Symbolic Links by changing the policy.

With gpedit.msc
Start gpedit.msc from the command line and grant/revoke specific users the permissions: Under "Computer Configuration" ->"Windows settings" -> "Security Settings" -> "Local Policies" -> "User Rights Assignments" -> "Create Symbolic Links".

Without gpedit.msc
Download PolsEdit and add users to SE_CREATE_SYMBOLIC_LINK_NAME.
Please make sure you log off and log on after changing policies, so that the changes become active.

Linkshell Extension can deal with the above granting of privileges, and if the Symblic Link Privilege is available avoids the UAC prompt.

Developer mode in Windows10
Another way to come around the UAC prompt would be toenable the developer mode, which is available since Windows10/14972.

Remote Capabilities

It is little known, but the SMB networking protocol supports operations to create remote Hardlinks, Junctions and Symbolic Links within SMB mapped network NTFS drives.

This feature is used by Link Shell Extension, to enable the creation of so called Remote Hardlinks, Remote Junctions, or Remote Symbolic Links. e.g.

• Map a network share
• Pick a file from that share
• Drop the file as Hardlink within the same share

A Hardlink has been created, which can be easily verified

Furthermore SMB1.0 also reports the reference count for Hardlinks and the junction origin for Junctions, which enables Link Shell Extension to show the properties dialog for remote files. Currently the reference count of a hardlink is reported via SMB1.0 in 90% correctly, so please be aware of this restriction.

LSE supports both, mapped network drives and UNC paths.

Mapped but not available network drives can in general be the reason for sloppy explorer startup performance. Delays of a few seconds can be experienced if explorer has to check all drive mappings, especially the ones which are not available. This gets worse, if LSE also checks the status of all drives.

To workaround this caveat the Remote Capabilities of Link Shell Extension can be switched on/off via the configuration tool.

Remote Hardlinks and the SMB version
There are differnet SMB Version implemented in different Windows versions which means different behaviour for hardlinks:

SMB1.0: Windows XP, Windows2000 ...
SMB2.0: Windows Vista ...
SMB2.1: Windows7/8, Windows Server 2008 R2 ...

SMB3.0: Windows10, Windows Server 2012 R2 ...

All of those version support the creation of hardlinks remotely, but since SMB2.0 one can not find out if a file on a remote drive is a hardlink or not.

This means, that e.g if you connect with your Windows XP machine to a SMB2.1 drive, which is provided by a Windows7/8/10 machine, you will not be able to see overlay icons for hardlinked files, but you will be able to create them remotley.

Removeable Media

LSE supports removable media, which have been formatted with NTFS, to create all kind of features it does for fixed drives too. The only limitation is that it intentionally won't work on removable media if they are mounted to drive A: or B:. The reason is that A: or B: are commonly used for floppy drives.

With removable media formatted to NTFS there is the slight chance that LSE reports 'Access denied' problems, when creating hardlinks or junctions. This is due to file object permissions on the removable NTFS drive, which have been created with a different computer on that removable media, thus causing this 'Access denied' messages. The solution here is to change the permission on that removable media as Administrator.

Very long Path

Explorer supports pathnames up to 256 characters, thus limiting all applications to that length for pathnames.

On the other hand NTFS supports pathnames with up to 32767 characters, so one might have already experienced pathnames, which are longer than 256 characters. To deal with that, LSE can handle Very Long Path up to 32767 characters with all operations.

Subst Handling

With the subst.exe command one can create driveletters, which point to a certain path on a NTFS volume. This means that two different driveletters in the end might resolve to locations on the same NTFS volume.
Link Shell Extension checks these situations when it comes to allow the creation of hardlinks, and as a consequence allows the creation of hardlinks among different logical drives if they resolve to the same NTFS volume.

ReFs Support

With Windows Server 2012 Microsoft introduced theReFS filesystem, which is the designated successor to NTFS. But the first implementation of ReFS can do nice things, but lacks a few important features from NTFS like the Hardlink support. Hardlinks are avaialble with ReFs3.5
Link Shell Extension supports ReFS so that one can create Symbolic Links, Mountpoints, Junctions on ReFS volumes. With ReFs version smaller than 3.5 it will throw an error message if a hardlink is about to be created on a ReFS volume. The impact on Link Shell Extension in detail is:

• ReFS drives as the destination of Delorean Copies will for sure fail, at least when creating the second backup in a Delorean set.
• SmartCopy/SmartMirror will fail as destination for hardlinks within the source.
• SmartMove will work. Since ReFS is expected to support the full set of NTFS functionality in a later release, Link Shell Extension has no checks implemented to tackle with the above constraints.

Third Party FileSystems

There are a lot of filesystems out by third party vendors nowadays, which support hardlinks, symlinks... In order to provide the LSE functionality on that drives, the supported filesystems can be configured:
Add your favourite filesystem name in a comma seperated list to

HKEY_LOCAL_MACHINE\SOFTWARE\LinkShellExtension\ThirdPartyFileSystems Changes to the known filesystems from the above registry key take efect after an explorer.exe restart.

If you don't know the name of the filesystem you might determine this by issuingln.exe from a command prompt.

ln --probefs x:

By default Btrfs is configured as a known third party filesystem.

Configuring your favourite filesystem to be recognized by LSE is on your own risk. Basically LSE would do all operations to the configured filesystems, which it does to NTFS. So make sure your filesystem supports the same primitives as NTFS does otherwise certain operations will fail.

Configuration

Link Shell Extension can be tweaked/configured to fit the different personal taste in some aspects. To ease this, Link Shell Extension has a companion called LSEConfig, which changes Link Shell Extension behaviour via a User Interface. Once started, LSEConfig will throw the famous UAC UAC dialog, because Link Shell Extensions settings are changed in the Windows registry.

Localisation
Link Shell Extension's UI and commands are available in a few languages. You can choose from

• English(default)
• Chinese
• Czech
• French
• German
• Greek
• Italian
• Japanese
• Korean
• Polish
• Portuguese Brazilian
• Russian
• Slovak
• Spanish
• Swedish
• Turkish
• Ukrainian Changing the UI Language of Link Shell Extension will need a restart of the explorer once Apply or Ok is pressed.

Smart Move
It might be useful to totally switch off Smart Move, if there are folders with really much folders. This can be acchieved by ticking the Smart Move checkbox.

Logging
All output of a LSE operation like SmartCopy, SmartMirror, or Delorean Copy is logged to the file %TEMP%\LinkShellExtension.log

Remote Capabilities
It might be useful to totally switch off Remote Capabilities, if there are lots of 'dead network drives' around. This can be acchieved by ticking the Remote Capabilities checkbox.

Outer Junction/Symbolic Link Handling
Decide whether Outer Junctions should be handled as Crop, be Unrolled, which is the default, or Spliced.

Symbolic Link Creation
By selecting either relative or absolute Link Shell Extension will create the target of Symbolic Links respective.

Copy Mode
By checking the Backup Link Shell Extension will run in Backup Mode.

Custom Overlay Icons

Link Shell Extension has built in overlay icons for junctions, hardlinks and symbolic links. Since icons are subject to individual taste, the icon used by Link Shell Extension can be specified.

Changing any settings related to overlay icons will ask for a restart of explorer when Apply or Ok is pressed.

Overlay Icon
Sometimes it might be useful to totally disable certain overlay icons from Link Shell Extension, which can be acchieved by ticking the checkbox for overlay icons.

Priority
Only one overlay icon can be shown with an icon, but many overlay handlers might apply to provide the overlay icon. To sort this out each overlay handler can specify a priority to explorer and explorer shows the overlay icon with highest priority.
High priority means lower number, with 0 as the highest priority

Custom Icon
By ticking the checkbox for custom icon the Browse... button gets enabled, and an icon can be selected. Keep in mind that custom icons are specific to each user.

General
Windows7/8/10 are a little bit special, because overlay icons for 256x256 must not be in the lower left corner of the icon, and must not be already smaller to perfectly 'overlay' an icon. 256x256 overlay icons must fill up the complete available icon, and also must not be resized.

Or in other words Windows7/8/10 takes any 256x256 icon and resizes it to 92x92, moves it to the left lower corner and overlays.

For all other resolutions smaller than 256x256, Windows7/8/10 you have to prepare an overlay icon in the lower left corner.

For my investigations the icon editor of choice capable of dealing with Windows7/8/10 icons wasRealWorld Icon Editor

Apply Changes
When you press OK or Apply on LSEConfigs dialog, settings will be taken over.

If changes were made to Link Shell Extensions language settings or settings related to overlay icons, you will be asked to confirm a restart of explorer.exe, so that your changes become effective. Restarting explorer.exe means, that e.g. any copy operation or other pending operation within explorer.exe is interrupted.

Backgrounders

Hardlinks are a feature common to many Unix based systems, but are not directly available with Windows. It is a feature, which must be supported by the file system of the operating system.

So what are Hardlinks? It is common to think of a file as being an association between a file name and a data object. Using Windows Explorer, the file system can be readily browsed, showing a 1:1 relationship between the_file name_ and the data object, but this 1:1 relationship does not hold for all file systems.

Some file systems, including UFS, XFS, and NTFS have a N:1 relationship between file name and the data object, hence there can be more than one directory entry for a file.

So, how does one create multiple entries for the same data object? In Unix there is a command line utility ln, which is used to create link entries for existing files, hence there are many file names, or so called Hardlinks, for the one data object.

For each HardLink created, the file system increments a reference count stored with the data object, i.e. it stores how many file names refer to the data object, this counter is maintained (by the file system) within the data object itself. When a file name referencing a data object is deleted, the data object’s reference count is decremented by one. The data object itself only gets deleted when the reference count is decremented to zero.

The reference count is the only way of determining whether there are multiple file name references to a data object, and it only informs of their number NOT there whereabouts.

Junctions are wormholes in the tree structure of a directed graph. By browsing a Junction a maybe far distant location in the file system is made available. Modifying, Creating, Renaming and Deleting files within a junction tree structure operates at the junction target, i.e. if you delete a file in a Junction it is deleted at the original location.

Symbolic Links are to files what Junctions are to folders in that they are both transparent and Symbolic. Transparency means that an application can access them just as they would any other file, Symbolism means that the data objects can reside on any available volume, i.e. they are not limited to a single volume like Hardlinks. Symbolic Links differ from Shortcuts in that they offer a transparent pathway to the desired data object, with a shortcut (.lnk), something has to read and interpret the content of the shortcut file and then open the file that it references (i.e. it is a two step process). When an application uses a symlink it gains immediate access to the data object referenced by the symlink (i.e. it is a one step process).

Limitations

• Supported platforms are NT4/W2K/WXP/W2K3/W2K3R2/W2K8/W2K8R2/W2K12/W2K12R2/WXP64/Vista/Vista/Windows7/8/10 in 32bit, 64bit or Itanium.
• Hardlinks can only be made on NTFS volumes, under the supported platforms.
• Hardlinks can only be made within one NTFS volumes, and can not span across NTFS volumes.
• Junctions can not be created on NTFS volumes with NT4.
• The Pick Link Source and Drop ... choices are only visible, if it’s possible to create Hardlinks/Junctions/Symbolic Links. E.G.: If you select a file on a FAT drive and press the action button, you wont see the Pick Link Source in the action menu, because FAT file systems, don't support Hardlinks/Junctions/Symbolic Links. This also happens, if you select source files on a network drive, or select a file as destination, etc.
• There is an OS limit of creating more than 1023 hardlinks per file. This is less known, but it is there.
• ReFs does not support hardlinks.

Frequently Asked Questions

• Q: On Windows7/8/10, the Save As... box shows symlinks with the white "shortcut" overlay, instead of the green symlink overlay.
  A: This happens if the processes shown during installation of Link Shell Extension were not closed. If you really run into this rare situation, a reboot will help.
• Q: However the value of the reference count is not updated when hardlinks are deleted. That is, when I add new hardlinks the value increases properly, but when I delete hardlinks, the value does not change. Is that a bug? Or there is a way of refreshing the Windows Explorer?
  A: Once a file is deleted in Explorer it is moved into Recycle Bin, but not really deleted. If you press Shift-Del for deleting a file instead of just pressing Del, the file really gets deleted and the reference count is decremented.
• Q: I could'nt make a successful hardlink for image or vector files - I mean, I was able to *make* the hardlink copy, but when I modified one file it didnt affect the other. I'm wondering do you know why this might be - could it be my otherwise quite normal computer (!) or could it be something to do with the hard link proccess ?
  A: You were able to make hardlinks successfully, but when you open a hardlinked file for edit, it depends on the editor associated to the file if the file either gets
  • opened, changed, the original deleted, and the new one saved ( ==> link broken )
  • opened, changed, and saved back ( ==> link alive )
• Q: When I deleted a source directory, its junction point is left behind in an non-operational state.
  Is there a way to prevent this? That is, for example, is it possible to automatically delete the junction points if the associated source is deleted? Or, is it possible to have a program prune such orphaned junctions afterwards?
  A: No sorry, Junctions are a one way relation, and if the targets disappears the junction points to an orphaned destination.
  If you have SmartMove enabled, at leastinner junctions/symbolic links are adapted
• Q: When I delete a symbolic link, which points to a zipped folder by pressing DEL, later on when I want to empty the recycle bin, explorer denies by showing me error message 0x80071128. What's wrong?
  A: Unfortunatley this is a bug in Explorer, and it only happens to symbolic links pointing to .zip files. The workaround is to move it manually out of recycle bin rename it, and then delete it once more.
• Q: I have created a symbolic link to an .exe and when I double click on it, I get the following error message:
  The specified path does not exist. Check the path and try again.
  A: Unfortunatley this is a bug in Explorer, and I don't have a clue how to come around this in explorer.
  If you start the symlink to an .exe from a command prompt it works fine, and even third party explorers like SpeedCommander can do this, but explorer seems to have a limitation
  Does anybody know the registry hack to enable this in explorer.exe? Drop me a line.
• Q: I double click on a symlink in explorer, which e.g. points to an .xls, and the explorer asks me to choose a program to open it.
  A: With KB3039066 Microsoft changed the behaviour of symlinks. Uninstall it and it will work again. See alsoSymbolic Link Type Changed
• Q: The overlay icons do not show up
  A: The number of different icon overlay handlers that the system can support is limited by the amount of space available for icon overlays in the system image list. There are currently 11 slots allotted with Windows 10 for icon overlays, some of which are reserved by the system.
  All is controlled by the alphabetical order of OverlayHandlers under
  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers If the OverlayHandlers for LinkShellExtension somehow slipped to a slot greater 15 under 32bit Windows or greater 11 with Windows 10, the LSE Overlay Icons won't show up.
  To manually boost the priority of LSE OverlayIcons, open the above registry location with regedit and prepend a blank

IconOverlayHardLink --> ' 'IconOverlayHardLink
IconOverlayJunction --> ' 'IconOverlayJunction
IconOverlaySymbolicLink --> ' 'IconOverlaySymbolicLink and either restart the explorer or log-off and log-on again. The point here is to change the alphabetical order by prepeding one blank. You might end up in a race to the top by adding more and mor blanks, since other OverlayHandlers such as DropBox' have already added a few blanks.

• Q: I'm trying to store Dropbox files only on removable storage instead of the internal 128gb of storage. My DropBox already contains lots of files. How do I accomplish redirecting the dropbox folder to the removeable storage?
  A:
  • Copy the whole dropbox folder from the internal storage under c:\users\[username]\dropbox to e.g x:\data\dropbox
  • Rename the dropbox folder c:\users\[username]\dropbox to e.g c:\users\[username]\dropbox_org
  • Pick Link Source x:\data\dropbox
  • In c:\users\[username] use Drop as and select Symbolic Link or Junction
  • If everything went fine finally delete c:\users\[username]\dropbox_org
• Q: When I create Symbolic links they appear in Explorer as 0 bytes. I cannot remember if this is expected or not?
  A: The resulting Symbolic Links show as 0 bytes in explorer.exe, that's expected.
• Q: I only changed the attribute of a file, even the timestamp and content are the same, but --delorean copies the file instead of linking to the old backupsets and just changing the attributes in the current backup set.
  A: The files in the backup sets of --delorean are hardlinked if they are the same. NTFS provides one set of timestamps and attributes for all hardlink-siblings of a file, so if a file needs different attributes in a backup, it has to be copied.
• Q: Broken Junctions (with non-existent targets) have their overlay icons displayed, but right clicking on them in Windows Explorer of Windows7 x64 SP1 and choosing "Properties" does not bring up the "Link Properties" tab. Consequently the information where the broken Junction is trying to point is not accessible and cannot be corrected manually.
  A: Unfortunatley this is an explorer problem, and LSE has no chance to intercept. Broken symlinks/juncitons can be easily repaired by the replacement junction/symbolic link feature
• Q: When I right click a symbolic link and go to properties, and click on Link properties, if the path contained inside is invalid, will give you the message "The name '(invalid path goes here)' specified in the Target box is not valid. Make sure the path and file name are correc.
  A: Unfortunatley this is an explorer problem, and LSE has no chance to intercept. Broken symlinks/juncitons can be easily repaired by the replacement junction/symbolic link feature

History

Status

The 3.9.3.x version is a stable version for the supported plattforms.

Acknowledgements

I wish to thank those who have contributed significantly to the development of Link Shell Extension. Those include:

Felix Kasza for the hardlink basics with NT4.
Nullsoft for the great lean and mean nsis installer
Jean-Pierre Bergamin for the drag and drop support samples.
Travis Illig suggested to add the overlay icons for junctions, which he uses in his Junction Shell Extension.
Mark Russinovich for tips onjunction
Philip Daniels for a technical writers documentation review
Daniel Thibault for the French localisation, and for a dozen of bug reports and feature requests.
Masatoshi Kimura for the symbolic link driver for WindowsXP.
Gerard Durand for the French translation of the documentation

Open Issues

• With Vista & Windows7 the column handler in explorer, providing the reference count, does not work, since Microsoft deprecated the interfaces with respect to this functionality.

License

• This program is provided as is. See license.txt from this distribution for legal issues.
• Link Shellextension uses tre as the regular expression machine. See the tre license.

Contact / Donations

Bug reports, or feature requests send toHermann Schinagl..
LSE is and will be freeware, but if LSE was really helpful for you and saved lots of your time please think of donations either via PayPal

or by flattring me

or by sending me a gift certificate from

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or by donating bitcoins:

bc1q4hvevwrmnwt7jg8vws0v8xajywhffl4gwca5av

Link Shellextension also has its page on Facebook, where you can find announcements for new releases, and you can discuss feature requests

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Link Shellextension broadcasts its release notes via RSS.

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