Windows – How to Delete Duplicate Files with a Batch File

batchcommand linewindows

I have a program that automatically copies files to a directory, and if it creates a duplicate it will name it like so:

file with duplicate.xxx
file with duplicate - 1.xxx
file with duplicate - 2.xxx

I need a way to delete all the duplicates with a Windows batch file.

Something along the lines of:

FOR %f IN (C:\files\*.*) DO del "%f - 1"

However, that will not work because that would resolve to file with duplicate - 1.xxx - 1

Best Answer

If you want to delete all the files with a name that ends in - ?, then you were close.

Try this:

FOR %%f IN ("C:\files\* - ?.*") DO del "%%f"

You will need to double up the percent signs if you are running it from a batch file. And test with an echo instead of a del first.

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Windows – Batch delete: Access is denied

To force a del command to delete read-only files, add the /F flag.

Apparently, a read-only file cannot normally be deleted by a batch file, although it can still be deleted through Windows Explorer. To check if your file is read-only, you can right click on the file and select properties, or enter attrib <filename> at the command prompt. This will show a series of letters corresponding to different file attributes.

R = Read-only file
A = Archive file
S = System file
H = Hidden file

You can remove the read-only tag by unchecking the box in the properties window or running the command attrib <filename> -R.

Windows – Removing duplicate files through batch files or Windows 7

Here’s a script (a.k.a. a “batch file”) that will do it for you in case you don’t want to download a program from somewhere:

@echo off
setlocal enabledelayedexpansion
for /r %%F in (*.m4a) do (
    set mp3name=%%~dpnF.mp3
    if exist !mp3name! (
        fc/b %%F !mp3name! > nul
        if errorlevel 1 (
            echo Warning: %%F and !mp3name! both exist but are not identical.
        ) else (
            echo DEL %%F
        )
    )
)

Interpretation:

for %%letter in (wildcard) do some_command scans the current directory for files matching the wildcard and executes the command with the variable identified by the letter set to the filename.
for /r %%letter in ... is the same but recursive.
( … ) lets you specify a block of commands instead of just one.
As indicated above, %%F is the name of the M4A file that was found.
%%~dpnF is the drive letter, path, and (base) name parts of %%F –– i.e., all but the extension. To this we append an .mp3 extension; i.e., a filename that is the same as %%F except it has an .mp3 extension. Assign this name to the mp3name variable.
If this file exists, do the next six lines. (Note that we are again using ( … ) to specify a block of commands.)
fc/b %%F !mp3name! > nul –– fc is file compare. fc likes to compare text files, so we say fc/b to do a binary comparison. So fc/b %%F !mp3name! compares the two files. > nul means don’t display the results of the comparison on the screen; we only want the script to know the result of the comparison.
if errorlevel 1 means do the following command(s) only if the immediately preceding command “failed”. In the case of fc, “failure” means that the files were not identical, so we have the script tell you that Hey_Jude.mp3 and Hey_Jude.m4a both exist but are not identical.
Finally, DEL %%F means delete the file. (echo DEL %%F means display the delete command, but do not execute it.)

Setup:

In Windows Explorer, go to the root (top) of your music directory, do New Text file, and give it a name.
Double-click on it to open (edit) it in Notepad. Copy and paste the above script. Save and exit.
Back in Windows Explorer, rename the Text (.txt) file to have a .bat extension. Ignore the warning; click on “Yes”.
Start a Command Prompt. cd to the above directory. Type the name of the script (batch) file (you may type the .bat extension, but you probably don’t need to). Verify that the list of DEL commands it reports looks reasonable. If it does,
Go back in Windows Explorer, right-click on the .bat file, and select Edit.
In Notepad, change echo DEL to DEL. Save and exit.
Back in Command Prompt, run the command again.

Best Answer

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