copy — Copy Files#

What it is#

copy is a built-in cmd.exe command that copies one or more files to a destination file or directory, and can also concatenate multiple source files into a single destination file. Present since MS-DOS 1.0, it handles simple flat-file copying well; for recursive tree copies, preserving attributes, or network paths, prefer xcopy or robocopy instead.

Availability#

copy is built into cmd.exe on every Windows version. PowerShell’s equivalent is Copy-Item (aliased cp, copy).

copy /?

Output:

Copies one or more files to another location.

COPY [/D] [/V] [/N] [/Y | /-Y] [/Z] [/L] [/A | /B ] source [/A | /B]
     [+ source [/A | /B] [+ ...]] [destination [/A | /B]]

Syntax#

The source can be a filename or wildcard; the destination can be a file name, a directory (trailing \ or existing folder name), or omitted to copy into the current directory.

copy [switches] source [destination]
copy source1 + source2 [destination]

Output: (shows count of files copied, or error)

Essential options#

Copying a single file#

The simplest form copies one file to another name or into a directory. If the destination is an existing directory, copy places the file inside it with the same name.

rem Copy to a new name in the same folder
copy report.docx report_backup.docx

Output:

        1 file(s) copied.

rem Copy into a directory (keeps original name)
copy report.docx C:\Backups\

Output:

        1 file(s) copied.

rem Copy to a different drive and folder
copy notes.txt D:\Archive\notes.txt

Output:

        1 file(s) copied.

Wildcard copies#

Wildcards * and ? let you copy groups of files matching a pattern. The destination must be a directory when copying multiple files; specifying a filename as destination with wildcards copies only the last matching file.

rem Copy all .txt files to an archive folder
copy *.txt C:\Archive\

Output:

        4 file(s) copied.

rem Copy files matching a partial name
copy report*.docx D:\Reports\

Output:

        3 file(s) copied.

Overwrite behaviour#

By default in an interactive session copy prompts before overwriting an existing file. Use /Y to suppress the prompt in scripts, or /-Y to force a prompt even when the COPYCMD environment variable would suppress it.

rem Silent overwrite — essential in batch scripts
copy /Y source.txt destination.txt

Output:

        1 file(s) copied.

rem Force prompt even if COPYCMD=/Y is set
copy /-Y source.txt destination.txt

Output:

Overwrite destination.txt? (Yes/No/All):

File concatenation#

Placing + between multiple sources merges them into a single destination file. This is copy’s unique feature absent in newer tools. ASCII mode (/A) stops reading each source at the first Ctrl+Z (ASCII 26) character; binary mode (/B) copies all bytes verbatim.

rem Concatenate three text files into one
copy header.txt + body.txt + footer.txt combined.txt

Output:

header.txt
body.txt
footer.txt
        1 file(s) copied.

rem Append one file to another (source and destination may overlap)
copy existing.txt + new_section.txt existing.txt

Output:

        1 file(s) copied.

rem Binary concatenation (no Ctrl+Z stripping)
copy /B part1.bin + part2.bin combined.bin

Output:

        1 file(s) copied.

Copying to CON, NUL, and other devices#

cmd.exe devices (CON, NUL, PRN, COM1, …) can be used as source or destination. CON is the console; copying to NUL discards output (useful for silencing command output).

rem Write console input to a file (Ctrl+Z then Enter to stop)
copy CON myfile.txt

Output:

(cursor waits for input; type lines, then Ctrl+Z + Enter)
        1 file(s) copied.

rem Send a file to the default printer
copy report.txt PRN

Output:

        1 file(s) copied.

Restartable mode for network copies#

/Z enables restartable mode: if the connection drops mid-copy the transfer can be resumed rather than starting over. This only applies when copying to or from network paths.

copy /Z \\myhost\share\bigfile.iso C:\Downloads\bigfile.iso

Output:

        1 file(s) copied.

Common pitfalls#

1. Wildcards with a filename destination copy only the last match — if the destination is output.txt and source is *.txt, only the final matching file ends up there. Use a directory destination for multi-file copies.
2. copy is not recursive — it will not descend into subdirectories; use xcopy /S or robocopy for trees.
3. Concatenation in ASCII mode may truncate binary data — /A is the default when combining files; always specify /B for binary concatenation.
4. Overwrite prompt suppressed by COPYCMD=/Y — if this environment variable is set, copy never prompts. Specify /-Y explicitly to get the prompt back.
5. Long paths (>260 chars) may fail — copy does not support extended-length paths (\\?\). Use robocopy for paths over the 260-character limit.

Real-world recipes#

Back up a config file before editing#

copy /Y app.config app.config.bak
notepad app.config

Output:

        1 file(s) copied.

Merge CSV exports into one file#

copy /B jan.csv + feb.csv + mar.csv Q1.csv

Output:

jan.csv
feb.csv
mar.csv
        1 file(s) copied.

Copy all files of a type to a backup folder silently in a scheduled task#

copy /Y C:\Logs\*.log C:\Backups\Logs\

Output:

        7 file(s) copied.

Create an empty file#

copy NUL placeholder.txt

Output:

        1 file(s) copied.

ASCII vs binary modes in depth#

/A and /B switches sit before or after a source/destination filename and apply to the closest preceding argument. The defaults are subtle: a single-file copy defaults to binary; a concatenation (+) defaults to ASCII for sources and binary for destination. ASCII mode stops reading at the first Ctrl+Z (0x1A) byte and appends a Ctrl+Z marker on write — which silently corrupts binary files. Always specify /B explicitly when copying anything that is not plain text.

rem Binary copy (default for single file)
copy /B installer.exe C:\Tools\installer.exe

Output:

        1 file(s) copied.

rem Demonstrating ASCII truncation — DON'T do this with binaries
copy /A binary.dat copy.dat
fc /B binary.dat copy.dat

Output:

        1 file(s) copied.
Comparing files binary.dat and COPY.DAT
00001A05: 1A FF

rem Per-argument switches: source binary, destination ASCII (rare)
copy source.txt /B + extra.txt destination.txt /A

Output:

source.txt
extra.txt
        1 file(s) copied.

Verification with /V#

/V reads back every copied file from the destination and compares it byte-for-byte to the source. It catches transient write errors that the filesystem accepts but later fails to read correctly. The cost is roughly 2x the copy time. Modern SSDs and NTFS journaling make /V largely redundant on local drives, but it remains useful for flaky USB sticks, optical media, and unreliable network shares.

copy /V important.docx D:\Backup\important.docx

Output:

        1 file(s) copied.

rem Verification failure surfaces as an error
copy /V flaky_file.bin E:\backup\flaky_file.bin

Output:

The data being verified does not match the file that was copied.

Restartable mode with /Z#

/Z enables a restartable transfer protocol designed for unreliable network links. If a copy is interrupted (network drop, transient share unavailability) /Z resumes from the last successful byte rather than starting over. The trade-off is significant per-block overhead, so reserve /Z for slow or unstable links — on a fast LAN or local copy it is pure overhead.

copy /Z \\myhost\share\bigfile.iso C:\Downloads\bigfile.iso

Output:

        1 file(s) copied.

Long path support and /B for size accuracy#

copy historically caps at MAX_PATH (260 characters) and does not honour LongPathsEnabled reliably. For multi-gigabyte files crossing the size cap on cmd.exe, switch to xcopy, robocopy, or PowerShell’s Copy-Item. The size in the 1 file(s) copied summary is accurate only when /B is used; ASCII mode reports the apparent text size.

File concatenation in depth#

The + operator is copy’s most distinctive feature. Multiple sources combine in order into a single destination. Sources may include wildcards: copy *.csv all.csv concatenates every matching file in the working directory (in directory-enumeration order, which is typically alphabetical on NTFS). Be aware: if the destination filename matches the wildcard, copy skips it to avoid infinite recursion — but only when it can detect the collision, which is not always.

rem Concatenate all CSVs in the folder
copy *.csv combined.csv

Output:

january.csv
february.csv
march.csv
        1 file(s) copied.

rem Concatenate with explicit binary mode for safety
copy /B part1.zip + part2.zip combined.zip

Output:

part1.zip
part2.zip
        1 file(s) copied.

rem Append in place — source and destination overlap
copy /B existing.log + new_entries.log existing.log

Output:

        1 file(s) copied.

COPYCMD environment variable#

The COPYCMD environment variable provides a default flag for copy, move, and xcopy. Setting COPYCMD=/Y suppresses overwrite prompts globally — which is convenient for scripts but dangerous in interactive sessions where you may want the safety prompt. Use /-Y on any individual command to force the prompt back on.

set COPYCMD=/Y
copy source.txt destination.txt
rem No prompt even if destination exists

Output:

        1 file(s) copied.

rem Force prompt despite COPYCMD=/Y
copy /-Y source.txt destination.txt

Output:

Overwrite destination.txt? (Yes/No/All):

PowerShell equivalents#

Copy-Item (aliases cp, copy, cpi) is the PowerShell native. It handles single files, wildcards, recursive trees (-Recurse), filters (-Filter, -Include, -Exclude), and produces typed objects. Unlike copy, it always preserves binary content correctly and natively supports long paths. PowerShell’s copy is not the cmd builtin — it is Copy-Item with PowerShell semantics, so /Y and /Z have no meaning there.

# Single file
Copy-Item report.docx report_backup.docx

Output: (none — silent success)

# Wildcard
Copy-Item *.txt C:\Archive\

Output: (none — silent success)

# Recursive directory copy with overwrite
Copy-Item C:\Projects\myapp C:\Backup\myapp -Recurse -Force

Output: (none — silent success)

# Copy with include/exclude filters
Copy-Item C:\Source\* C:\Dest\ -Recurse -Include '*.py','*.md' -Exclude '*.pyc'

Output: (none — silent success)

# Concatenate files (no native + operator; use Get-Content / Set-Content)
Get-Content header.txt, body.txt, footer.txt | Set-Content combined.txt

Output: (none — silent success)

# Binary concatenation
$bytes = foreach ($f in 'part1.bin','part2.bin') { [IO.File]::ReadAllBytes($f) }
[IO.File]::WriteAllBytes('combined.bin', ($bytes | ForEach-Object { $_ }))

Output: (none — silent success)

# Dry run with -WhatIf
Copy-Item C:\Source\* C:\Dest\ -Recurse -WhatIf

Output:

What if: Performing the operation "Copy File" on target "Item: C:\Source\a.txt Destination: C:\Dest\a.txt".

# Long path with literal path
Copy-Item -LiteralPath '\\?\C:\very\long\source\file.dat' -Destination 'D:\Backup\'

Output: (none — silent success)

CMD vs PowerShell vs bash comparison#

Common pitfalls (continued)#

6. ASCII mode truncates at Ctrl+Z — copy file.exe other.exe defaults to binary for single-file copies, but copy a + b out defaults to ASCII for sources. Always pass /B for non-text.
7. copy does not preserve timestamps when concatenating — the destination gets the current time. Use robocopy /COPY:DAT /DCOPY:T if timestamps matter.
8. No recursive flag — copy cannot descend into subdirectories. Reach for xcopy /S /E or robocopy /E for trees.
9. Wildcards with filename destination — copy *.txt out.txt writes only the last matched file to out.txt if the destination is treated as a file. Always end the destination with \ to force directory interpretation.
10. Sparse files and alternate data streams are not preserved — copy collapses NTFS sparse files into their physical representation and drops ADS. Use robocopy /COPY:DAT (or /B for backup mode) for those.
11. Junctions and symlinks — copy follows them and copies the target file or directory. Use xcopy /B or robocopy /SL to copy the link itself.
12. COPYCMD=/Y in user environment — a global COPYCMD=/Y removes the safety prompt everywhere. Audit set output if interactive copies silently overwrite.

Real-world recipes (continued)#

Combine log shards in chronological order#

rem Each shard sorts alphabetically by ISO date prefix
copy /B shard_2026*.log combined.log

Output:

shard_20260101.log
shard_20260102.log
...
        1 file(s) copied.

Daily snapshot of a config file with date stamp#

set STAMP=%DATE:~-4,4%%DATE:~-10,2%%DATE:~-7,2%
copy /Y app.config "C:\Backup\app.config.%STAMP%"

Output:

        1 file(s) copied.

Verify copy by hash comparison#

copy /Y bigfile.iso D:\bigfile.iso
for /F %a in ('certutil -hashfile bigfile.iso SHA256 ^| findstr /V ":"') do set H1=%a
for /F %a in ('certutil -hashfile D:\bigfile.iso SHA256 ^| findstr /V ":"') do set H2=%a
if "%H1%"=="%H2%" (echo Match) else (echo MISMATCH)

Output:

        1 file(s) copied.
Match

Bundle CSV exports into a single archive#

copy /B exports\*.csv consolidated.csv
echo Combined %ERRORLEVEL%

Output:

        7 file(s) copied.
Combined 0

PowerShell: copy preserving timestamps and ACLs#

Copy-Item C:\Source\* C:\Dest\ -Recurse -Force
Get-ChildItem C:\Source -Recurse | ForEach-Object {
    $dest = $_.FullName -replace [regex]::Escape('C:\Source'), 'C:\Dest'
    if (Test-Path $dest) {
        Get-Acl $_.FullName | Set-Acl -Path $dest
        (Get-Item $dest).LastWriteTime = $_.LastWriteTime
    }
}

Output: (none — silent success)

Create a sparse placeholder of an expected size#

copy NUL placeholder.dat
fsutil file setvaliddata placeholder.dat 1048576

Output:

        1 file(s) copied.
Valid data length is changed

Touch — bump a file’s modified time without changing content#

copy documents an idiomatic “touch” trick: concatenate the file with nothing (two trailing commas indicate the destination is intentionally omitted), and the file is rewritten with the current timestamp.

rem Update mtime on existing.log to now, leave content untouched
copy /B existing.log +,,

Output:

existing.log
        1 file(s) copied.

This is the cmd equivalent of touch -m existing.log on Linux. PowerShell’s version is (Get-Item existing.log).LastWriteTime = Get-Date.

Sources#

Microsoft Learn — copy command — Authoritative reference for /d /v /n /y /-y /z /a /b, the + concatenation operator and ASCII/binary mode interplay, the COPYCMD environment variable, device-name destinations (PRN, COMn), and the +,, timestamp-touch idiom.

See also#

• xcopy — recursive directory copy with attribute filtering; the historical step up from copy.
• robocopy — production-grade copy and sync with retry, mirror, and logging.
• move — copy-then-delete in one step.
• del — remove files; inverse of copy.
• fc — verify two files differ byte-by-byte; useful after copy.
• certutil -hashfile — verify content integrity post-copy.
• PowerShell Copy-Item, Start-BitsTransfer — modern alternatives with progress and resume.
• Linux cp, rsync — Unix equivalents.