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To verify a copied file, compare the source and destination with Get-FileHash (SHA-256 by default) or run fc.exe /b for a byte-by-byte comparison. If you are still performing the copy with the classic copy command, add /v to check that each new file was written correctly. For folder transfers, keep and review a Robocopy log, then hash any files for which you need content-level proof. These checks answer different questions: a write verification checks the copy operation, a binary comparison checks two files directly, and matching hashes establish that the compared files have identical contents.
Choose the verification that matches your question
“Verified” can mean several things. Decide which result you need before choosing a command.
| Method | Best use | What it establishes | Important limitation |
|---|---|---|---|
copy /v |
Checking a file while the classic copy command writes it |
Windows verifies that the newly written file was recorded correctly. | It is slower and is not described as a later source-versus-destination hash comparison. |
Get-FileHash |
Checking one file or comparing source and destination files | Computes a cryptographic hash. Identical SHA-256 values indicate identical contents for the two files being compared. | You must calculate the hash on both copies and compare the values. |
fc.exe /b |
Directly comparing two files | Compares the files byte by byte and reports differences. | It compares two files directly; it does not create a reusable hash value. |
| Robocopy logging | Reviewing a directory transfer | Provides a transfer record that you can inspect after the job completes. | A successful log entry is not, by itself, a cryptographic comparison of every source and destination file. |
The commands documented by Microsoft apply to Windows 10 and Windows 11. The hash examples work in Windows PowerShell and PowerShell 7; the Microsoft page for PowerShell 7.5 documents SHA-256 as the default algorithm.
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Compare one copied file with SHA-256 in PowerShell
Hash comparison is the clearest general-purpose check when you already have a source file and a destination file. A hash is a value calculated from the file’s contents. Calculate it independently for both paths and compare the Hash properties.
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Calculate both hashes
- Open PowerShell. You do not need a paid utility for this check.
- Run the command for the original file:
Get-FileHash -LiteralPath 'C:sourcefile.ext'Then run it for the copy:
Get-FileHash -LiteralPath 'D:destinationfile.ext'Keep the paths quoted. Quoting prevents spaces in names such as C:Project Filesreport.pdf from being parsed as separate arguments. By default, Get-FileHash uses SHA-256. Each result includes the path, the algorithm, and a hexadecimal Hash value.
Interpret the result
- If the two SHA-256 values are identical, Microsoft describes that as indicating the files have exactly the same content.
- If the values differ, the files are not identical. Check that you selected the intended source and destination, then investigate the copy or the files themselves.
- A matching hash says nothing about file permissions, ownership, timestamps, or other metadata. Those properties must be checked separately when they matter.
You can make the comparison explicit instead of visually scanning two long hexadecimal strings:
$sourceHash = (Get-FileHash -LiteralPath 'C:sourcefile.ext').Hash
$destinationHash = (Get-FileHash -LiteralPath 'D:destinationfile.ext').Hash
if ($sourceHash -eq $destinationHash) {
'Match: file contents are identical'
} else {
'Difference: file contents do not match'
}This comparison uses the default SHA-256 algorithm on both sides. If you select another algorithm, select the same one for both files and record that choice with your verification result.
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Microsoft describes fc as a command that compares two files or sets of files and displays their differences. The /b switch requests binary comparison, so Windows examines the files byte by byte rather than treating them as text.
fc.exe /b "C:sourcefile.ext" "D:destinationfile.ext"Use the complete executable name, fc.exe, when running this from PowerShell. PowerShell has an fc alias, so typing only fc can invoke a different command. In Command Prompt, fc /b is sufficient, but spelling out fc.exe is unambiguous in either shell.
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Read the comparison outcome
- When the files match,
fc.exereports that no differences were found. - When they differ, the command identifies differences rather than silently treating the files as equal.
- If Windows reports that a file cannot be found or opened, correct the path, drive letter, permissions, or availability of the removable or network volume before interpreting the result.
fc.exe /b is useful when you want a direct comparison and do not need to store a digest. Hashes are more convenient when you need to record a short value, compare files at different times, or ask someone else to verify against an independently supplied value.
Verify writes during a classic copy operation
If you have not copied the file yet and are using the built-in copy command, the /v option asks Windows to verify that each new file was written correctly. Microsoft notes that this check slows the command because each sector recorded on disk is checked. Its documentation explains that although recording errors are rare, /v can be used for critical data.
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When /v is worth the extra time
- Use it when a write error would be costly and the transfer is small enough that the additional checking time is acceptable.
- Do not mistake its successful completion for proof that permissions, timestamps, or ownership were copied as intended.
- For a large directory job, consider a logged Robocopy transfer and targeted hash comparisons rather than assuming that a write check covers every later requirement.
Use Robocopy logs for directory transfers
Robocopy is intended for directory copy operations and supports logging. Microsoft recommends creating a log and reviewing it after the command completes. A simple logged invocation is:
robocopy "C:Source" "D:Destination" /LOG:"C:Logscopy.txt"Choose a log path that exists and that you can write to. The log gives you a record of what Robocopy attempted and reported, which is valuable when a job contains many files or runs unattended.
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What the log can and cannot prove
Read the log as a transfer record. It can show the operation’s reported results and help you locate skipped, copied, or failed items. The cited Microsoft documentation does not state that a successful log entry calculates cryptographic hashes for every source and destination file. Therefore, do not describe the log alone as proof that every file’s bytes match.
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Decide which metadata to copy
Robocopy lets you choose the categories of information copied with the /COPY flags. The documented categories are:
| Flag category | Information |
|---|---|
D |
File data |
A |
Attributes |
T |
Timestamps |
S |
NTFS access-control lists |
O |
Owner information |
U |
Auditing information |
Microsoft documents the default as data, attributes, and timestamps. A content match therefore does not establish that permissions, owner information, or auditing information also match. If metadata is part of your requirement, define the required /COPY categories before the transfer and verify those properties with appropriate Windows security and file-property tools afterward.
Hash an entire folder when every file matters
There is no single Robocopy log line that should be treated as a cryptographic proof for an entire tree. When you need content-level assurance for many files, apply the same two-file hash comparison repeatedly. The following PowerShell pattern checks every source file, reports missing destination files, and reports content differences. It does not report destination-only extras, and it does not compare metadata.
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$sourceRoot = (Resolve-Path 'C:Source').Path.TrimEnd('')
$destinationRoot = (Resolve-Path 'D:Destination').Path.TrimEnd('')
$differences = foreach ($sourceFile in Get-ChildItem -LiteralPath $sourceRoot -File -Recurse) {
$relative = $sourceFile.FullName.Substring($sourceRoot.Length).TrimStart('')
$destinationFile = Join-Path $destinationRoot $relative
if (-not (Test-Path -LiteralPath $destinationFile -PathType Leaf)) {
[pscustomobject]@{ Path = $relative; Status = 'Missing at destination' }
continue
}
$sourceHash = (Get-FileHash -LiteralPath $sourceFile.FullName).Hash
$destinationHash = (Get-FileHash -LiteralPath $destinationFile).Hash
if ($sourceHash -ne $destinationHash) {
[pscustomobject]@{ Path = $relative; Status = 'Content differs' }
}
}
$differences | Format-Table -AutoSizeAn empty output means that every source file examined had a destination file with the same SHA-256 value. It does not mean the destination contains no additional files, nor does it establish matching permissions or timestamps. If the source or destination includes junctions, reparse points, inaccessible files, or changing files, decide how those cases should be handled before relying on an automated result.
Select an algorithm that fits the risk
SHA-256 is the default for Get-FileHash in the Microsoft PowerShell 7.5 documentation and is the sensible default for ordinary integrity checks. Microsoft’s Windows PowerShell 5.1 documentation warns that MD5 and SHA-1 are no longer considered secure. Those older algorithms may be used for simple change validation, but they should not be used for files that need protection from attack or tampering.
A matching hash demonstrates matching content only relative to the algorithm and the two files you hashed. It does not authenticate who created a file or prove that an attacker did not replace both the file and the expected hash. For authenticity, obtain an expected hash or a digital signature through an independently trusted channel and compare against that value.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Understand the related verify command
Windows also has a verify command that controls whether cmd.exe verifies files written correctly to disk. Its documented forms are:
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verifyverify without an argument displays the current setting. This is a command-interpreter setting, whereas copy /v is an explicit option on a particular copy command. Neither replaces a post-copy source-versus-destination hash comparison when you need proof that two existing files contain the same bytes.
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Troubleshoot a failed or confusing verification
The command says the path does not exist
Confirm the drive letter, spelling, extension, and destination folder. Use -LiteralPath in PowerShell and keep the entire path inside quotes. A path containing brackets, wildcard characters, or spaces can otherwise be interpreted differently than you intended.
You receive access denied
Make sure your account can read both files and that the destination volume is mounted. A hash or binary comparison cannot inspect a file that the current process cannot open. If the file is protected, use an approved administrative procedure rather than weakening permissions permanently.
The hashes differ immediately after copying
Check that the source file was not still changing during the copy. Re-run the hash on the source and destination after applications have closed the source. Also check that you did not compare files with similar names in different folders, and inspect the copy log for skipped or failed items.
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Invoke fc.exe, not just fc, because the shorter name can resolve to PowerShell’s alias. Quote both file paths and include /b so the comparison is binary.
The check is taking a long time
Reading a file to hash or compare it requires processing its contents. The /v option also deliberately adds a write verification pass, so Microsoft documents it as slower. For a large transfer, retain a Robocopy log, then hash the files whose contents require the strongest assurance instead of assuming the log is a hash report.
The bytes match but the file still behaves differently
Content equality does not imply metadata equality. Review timestamps, attributes, NTFS access-control lists, owner information, and auditing information when the application depends on them. Revisit the Robocopy /COPY categories used for the transfer and verify the relevant properties separately.
A practical decision checklist
- Copy has not started: use
copy /vif you are using the classiccopycommand and want write verification during the operation. - One existing file: calculate SHA-256 with
Get-FileHashfor both paths and compare theHashvalues. - Need a direct binary result: run
fc.exe /bwith the source and destination paths. - Many files: run Robocopy with
/LOG, review the transfer record, and hash files or sets of files that require content-level proof. - Permissions or timestamps matter: treat those as separate metadata checks; a matching content hash does not cover them.
- Security-sensitive integrity: use SHA-256 or a stronger approved algorithm and compare with an independently trusted expected hash or signature. Do not rely on MD5 or SHA-1 for protection against tampering.
Record the result so it can be audited
For a repeatable process, save the source path, destination path, algorithm, hash values, date, and the command or script used. For a directory transfer, keep the Robocopy log alongside that record. Note whether you verified only file contents or also checked metadata. This prevents a later reader from mistaking a write check, a transfer log, and a cryptographic comparison as interchangeable results.
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