|Purpose:||Search for and optionally delete or symlink duplicated files.|
|Format:||DEDUPE [ranges] [/= /A:[[-|+]rhsadecijopt /D /H /L /N[defjnstz] /P /Q /R /S[[+]n] /SHA1 /SHA256 /SHA384 /SHA512 /T /V /W[n]] filename directory [directory...]|
|filename||The filename to search for (* for everything)|
|directory||The directories (and optionally subdirectories) to search|
File Completion Syntax:
The default filename completion syntax is:  * [2*] dirs
DEDUPE searches one or more directories, assigns a hash value to files, and then compares the hash value to all the other files. On slow systems (and particularly in x86 Windows) this can take a while, so you should try to reduce the amount of searching & hashing by using ranges, and not try to dedupe an entire disk at one time.
DEDUPE assumes that the first file it finds for each hash is the original file.
Remove all the duplicate files from the E: drive:
dedupe /d /s /SHA256 * e:\
|/=||Display the DEDUPE command dialog to help you set the filename and command line options. The /= option can be anywhere on the line; additional options will set the appropriate fields in the command dialog.|
|/A:||Dedupe those files that have the specified attribute(s) set. See Attribute Switches for information on the attributes which can follow /A:. Do not use /A: with @file lists. See @file lists for details.|
You can specify /A:= to display a dialog to help you set individual attributes.
|/L||Convert duplicate files to symlinks of the first file. Note that to create symlinks, you must be in an elevated session.|
|d||Skip hidden directories (when used with /S)|
|e||Don't display errors|
|f||Don't display the bytes freed in the summary|
|j||Skip junctions (when used with /S)|
|s||Don't display the summary|
|t||Don't update the CD / CDD extended directory search database (JPSTREE.IDX)|
|z||Skip system directories (when used with /S)|
|/SHAx||Hash algorithm to use. The default is SHA256; you can optionally use SHA1 or SHA512. SHA1 is slightly faster but potentially insecure.|