Robust File and Folder Copy.
By default Robocopy will only copy a file if the source and destination have different time stamps or different file sizes.

## = New Option in Windows 8 and Windows 10.

Robocopy, for 'Robust File Copy', is a command-line directory and/or file replication command for Microsoft Windows. Robocopy functionally replaces Xcopy, with more options. Created by Kevin Allen 1 and first released as part of the Windows NT 4.0 Resource Kit, it has been a standard feature of Windows since Windows Vista and Windows Server.

Robocopy EXIT CODES

Robocopy /S /E /A+:H D: dir1 data E: backup data Mirror copy a directory. Below Robocopy command creates a replica of the source folder in the specified destination folder. Robocopy /MIR sourceFolder destinationFolder. This command also deletes any extra files that are present in the destination and are not present in source. Mar 13, 2021 Robocopy is a robust file copy command for the Windows command line. It allows users to copy files, directories, and even drives from one location to another.

By copying only the files that have changed, robocopy can be used to backup very large volumes.

If either the source or desination are a 'quoted long foldername' do not include a trailing backslash as this will be treated as an escape character, i.e. 'C:some path' will fail but 'C:some path' or 'C:some path.' or 'C:some path' will work.

If creating a progress logfile with /LOG , specify a destination directory that already exists, robocopy will create the file but will not create a log directory automatically.

Long FileNames

ROBOCOPY will accept UNC pathnames including long pathnames over 256 characters long. When copying a tree of multiple files and subfolders, if the destination folder has a longer name than the source folder, then it is likely some files will hit the 256 character limit.
Even when Robocopy successfully copies such files, other software may refuse to open them.

For compatibility with old software the User Profile folder contains a number of Junction Points, 'Application Data', 'My Documents', Recent, 'Send To' etc.
By default RoboCopy /S will follow a junction point in the source and copy the contents to a standard folder in the destination.

In the case of 'Application Data' on Windows 7 Documents and Settings%USER%Application Data is a junction point to Users%USER%AppDataRoaming, which in turn can contain the Application Data junction as a subdirectory.

In cases like this RoboCopy can create a recursive loop copying the folder into itself until the NTFS max folder name length of 32,767 characters is exceded. To avoid this use the /XJ or /XJD option.

Symbolic Links and Junctions

/sl Will copy symbolic links, this will copy a File Symbolic Link only, creating a new symbolic link at the destination.

For a Directory Symbolic Link, a Junction, or a Hard Link, RoboCopy will follow the source and copy the contents to a standard folder in the destination. For a backup program this is usually the desired behaviour.

To exclude Junction points from being copied you can use the options /XJ, /XJD, /XJF this will prevent the source files from being copied. The Junction Point itself will not be copied (either with or without these flags).

An NTFS junction point in the Destination will not be deleted by RoboCopy, if you select any options which delete from the destination (/purge, /mir) and the destination contains a junction, RoboCopy will blindly follow that junction and delete the contents.
The /XJ options do not affect this as they only exclude junctions from the source.

File Attributes [RASHCNETO]

These options accept any combination of the following letters, when several are specified, will match if any or all items match:

Multithreaded copying with /MT:n will improve performance until the network and file system latency become the limiting factor, /MT:4 is a good place to start testing.

To limit the network bandwidth used by robocopy, specify the Inter-Packet Gap parameter /IPG:n
This will send packets of 64 KB each followed by a delay of n Milliseconds.

Robocopy will fail to copy files that are locked by other users or applications, so limiting the number of retries with /R:0 will speed up copying by skipping any in-use files. The Windows Volume Shadow Copy service is the only Windows subsystem that can copy open files. Robocopy does not use the Volume Shadow Copy service, but it can backup a volume shadow that has already been created with VSHADOW or DISKSHADOW.

All versions of Robocopy will copy security information (ACLs) for directories, version XP010 will not copy file security changes unless the file itself has also changed, this greatly improves performance.

/REG Writes to the registry at HKCUSoftwareMicrosoftResKitRobocopy

/XX (exclude extra) If used in conjunction with /Purge or /Mir, the exclude extra switch will take precedence and prevent any files being deleted from the destination.

/B (backup mode) will allow Robocopy to override file and folder permission settings (ACLs).

To run ROBOCOPY under a non-administrator account will require SeBackupPrivilege (backup files privilege), to copy security information auditing privilege is also required, plus of course you need at least read access to the files and folders.

ERROR 5 (0x00000005) Changing File Attributes .. Access is denied
This error usually means that File/Folder permissions or Share permissions on either the source or the destination are preventing the copy, either change the permissions or run the command in backup mode with /B.

Robocopy 'Jobs' and the 'MOnitor source' option provide an alternative to setting up a Scheduled Task to run a batchfile with a Robocopy command.

Examples:

Simple copy of all files from one folder to another:

Copy all .jpg and .bmp files from one folder to another:

Robocopy Options

Copy files including subfolders (even empty ones /E)
If this command is run repeatedly it will skip any files already in the destination, however it is not a true mirror as any files deleted from the source will remain in the destination.

List files over 32 MBytes in size:

Robocopy Download

Move files over 14 days old: (note the MOVE option will fail if any files are open and locked.)

Backup a Server:
The script below copies data from FileServ1 to FileServ2, the destination holds a full mirror along with file security info. When run regularly to synchronize the source and destination, robocopy will only copy those files that have changed (change in time stamp or size).

Robocopy J Switch

@ECHO OFF
SETLOCAL

SET _source=FileServ1e$users

SET _dest=FileServ2e$BackupUsers

SET _what=/COPYALL /B /MIR
:: /COPYALL :: COPY ALL file info
:: /B :: copy files in Backup mode. Ausum systems software.
:: /MIR :: MIRror a directory tree
SET _options=/R:0 /W:0 /LOG:C:batchRoboLog.txt /NFL /NDL
:: /R:n :: number of Retries
:: /W:n :: Wait time between retries
:: /LOG :: Output log file
:: /NFL :: No file logging
:: /NDL :: No dir logging
ROBOCOPY %_source% %_dest% %_what% %_options%

Run two robocopy jobs at the same time with START /Min

Robocopy Switch List

Copy only permission changes (additions and removals) assuming we already have a copy of the data:
ROBOCOPY FileServerC$ SVR-Backupsc$Backups /E /Copy:S /IS /IT

Availability

Robocopy XP027 is a standard command in Windows 7 and above. Robocopy does not run on Windows 95, or NT 3.5. (Robocopy is a Unicode application). The Microsoft Robocopy GUI will install Robocopy XP026 to C:Windowssystem32, this version can can run on older OS's, and includes some features from XP027 (/BYTES) but has competely broken errorlevel handling.

Bugs

Robocopy Gui

Robocopy /MOVE or /PURGE can be used to delete empty folders by setting source and destination to the same folder, but this does not always deal with nested empty folders in a single pass. It will work if Windows Explorer is closed.

When copying files larger than 2 GB from some iSCSI/SAN volumes the copy operation may fill all available RAM and then stall out. This typically happens when the RAID virtual disk on the controller is set to write-through caching rather than write-back caching.
Copy utilities such as TeraCopy ($) and BITS will workaround this issue because they copy the file in larger blocks, however the cost of this is that copying smaller files may then be slower than using Robocopy. The /IPG option may help with this issue.

Version XP026 returns a success errorlevel even when it fails.

“One, a robot may not injure a human being, or through inaction, allow a human being to come to harm” - Isaac Asimov, Laws of Robotics from I. Robot, 1950

Related commands:

Robocopy EXIT CODES
Robocopy /MIR switch – Security changes added to Robocopy in Windows Vista.
Set-LastWrite - Reset Folder 'Last Modified' to the most recent file in the folder (PowerShell function).
DiskShadow - Copy open files (Shadow copies).
COPY - Copy one or more files to another location.
Robocopy GUI - Technet magazine (installs Robocopy XP026).
RichCopy free GUI copy utility - Ken Tamaru [MSFT].
DelTree - Delete subfolders and files / delete empty folders.
Convert KB/MB - Bits and Bytes, bandwidth calculations .
Q323275 - Copy Security info without copying files (/SECFIX or /COPY:S).
Equivalent PowerShell command: BITS cmdlets - Background Intelligent Transfer Service.
Equivalent bash command: rsync - Remote file copy (Synchronize file trees).