PowerShell-HashCopy

This PowerShell module contains cmdlets for copying and comparing specific files between two paths, where those files have been determined to have changed via a computed hash value. This is useful if you need to sync specific file changes from one directory to another but cannot trust the modified date of the files to determine which files have been modified (for example, if the source files has been cloned from a source control system and as a result the modified dates had changed).

You should of course be confident that if there is a difference between two files, it is the copy you have specified as being in the source -Path that you want to use to overwrite the copy in the -Destination path. New files (files that exist in the source path but not in the destination) will also be copied across, including any directories in their paths that may be missing in the destination folder.

You can synchronise an entire directory tree by using the -Recurse parameter.

This module is cross-platform and works anywhere PowerShell runs, including Windows, Linux, and macOS (via PowerShell 7+ / PowerShell Core).

Installation

The module is published in the PSGallery, so if you have PowerShell 5 or newer can be installed by running:

Install-Module HashCopy -Scope CurrentUser

Cmdlets

A full list of cmdlets in this module is provided below for reference. Use Get-Help <cmdlet name> with these to learn more about their usage.

Cmdlet	Description
Copy-FileHash	Copies any files between two directory paths that are new or have changed based on computed hash value.
Compare-FileHash	Compares files from one location to another based on determining change via computed hash value.

Usage

Copy-FileHash

You can use the Copy-FileHash cmdlet to sync a single path by providing it with -Path and -Destination parameters:

Copy-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files

This will compute the hash for all files in each directory (and all sub-directories, due to -Recurse) via the Get-FileHash cmdlet and then will copy any changed and new files from the source path to the destination path.

As this module is cross-platform, the same cmdlet works identically on Linux or macOS using native paths:

Copy-FileHash -Path /home/user/Some/Files -Destination /mnt/backup/Some/Other/Files

You can include all the sub-folders of the source -Path by adding -Recurse:

Copy-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files -Recurse

You can specify a -LiteralPath instead of a Path if you want to avoid wildcard characters from being interpreted as such:

Copy-FileHash -LiteralPath C:\Some\Files -Destination D:\Some\Other\Files -Recurse

You can remove files from the Destination path that are not in the Source path by adding -Mirror:

Copy-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files -Mirror

You can have the destination file objects returned by adding -PassThru:

Copy-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files -Recurse -PassThru

You can Force the overwrite of read-only files in the Destination path by adding -Force:

Copy-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files -Force

You can specify the algorithm that Get-FileHash uses to create the Hash by using -Algorithm:

Copy-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files -Algorithm MD5

Valid -Algorithm values are: SHA1 | SHA256 | SHA384 | SHA512 | MACTripleDES | MD5 | RIPEMD160.

Compare-FileHash

If you'd like to check which files will be copied from a source path before actually using Copy-FileHash, you can use Compare-FileHash. This cmdlet outputs file objects for any new or modified file having performed the same comparison as the Copy- cmdlet (e.g via using Get-FileHash of the source and destination file to determine if they are different).

Check which files would be copied from one single directory to another:

Compare-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files

Check which files would be copied between one directory tree and another (including all sub-directories):

Compare-FileHash -Path C:\Some\Files -Destination D:\Some\Other\Files -Recurse

As with Copy-FileHash you can use -LiteralPath instead of -Path to have paths interpreted literally.

The same cmdlets work on Linux or macOS, for example comparing two directories on macOS:

Compare-FileHash -Path /Users/me/Some/Files -Destination /Volumes/Backup/Some/Other/Files -Recurse