Way to append files efficiently using the DOS copy command

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Using the DOS copy command syntax to concatenate files:

copy file1.txt+file2.txt all.txt

I know I can do this…

copy file1.txt+file2.txt file1.txt

Is this efficient? Is it doing what I'm expecting? It works, but I want to know is it actually appending to file1.txt or is it copying file1.txt (bad), concatenating file2 and then renaming to file1.txt (which is not efficient)?

Best Answer

copy is copying file1.txt and file2.txt into memory, concatenating them then writing out to file1.txt. It's not copying to a new file then renaming that file so really there's not much extra disk I/O.

You can also use type.

type file2.txt >> file1.txt

The >> operator appends text. But that will, of course, not work for binary files.

Related Solutions

Batch file: Change names on files with certain extensions in multiple directories based on the directory name and copy into one directory

Ok, here's one. You might want to consider using something more flexible than a batch file; a simple C++ program would have been much easier. Batch does not play nice with the string manipulation necessary to extract the directory name.

@ECHO OFF

SETLOCAL EnableDelayedExpansion

SET _destination=%~1
SHIFT

SET _source=%~1
SHIFT

SET _cmdstring=dir /b /s

:LoopGetExt
    SET _cmdstring=%_cmdstring% "%_source%\*%~1"
    SHIFT
    IF NOT "%~1"=="" GOTO LoopGetExt
::End LoopGetExt

FOR /F "tokens=*" %%i IN ('%_cmdstring%') DO (
        SET _fullpath=%%i
        SET _splitpath=!_fullpath:\=^

!
        SET _filename=%%~ni%%~xi
        FOR /F "tokens=*" %%j IN ("!_splitpath!") DO (
            IF NOT "%%j"=="!_filename!" SET _dirname=%%j
        )

        ECHO "%%i" =^> "%_destination%\!_dirname!_!_filename!"
        COPY "%%i" "%_destination%\!_dirname!_!_filename!"
)

ENDLOCAL

At the moment nothing has been hardcoded: to use it, do this.

copyfiles.bat <destination> <source> <ext> [ext]

e.g.

copyfiles.bat "C:\Dest" "C:\Source" .txt .xml .csv .log

EDIT (as per request in first comment)

::copyfiles.bat <destination> <source> <ext> [ext]
::e.g.
::copyfiles.bat "C:\Dest" "C:\Source" .txt .xml .csv .log

@ECHO OFF

SETLOCAL EnableDelayedExpansion

SET _destination=%~1
SHIFT

SET _source=%~1
SHIFT

SET _cmdstring=dir /b /s

:LoopGetExt
    SET _cmdstring=%_cmdstring% "%_source%\*%~1"
    SHIFT
    IF NOT "%~1"=="" GOTO LoopGetExt
::End LoopGetExt

FOR /F "tokens=*" %%i IN ('%_cmdstring%') DO (
        SET _fullpath=%%i
        SET _splitpath=!_fullpath:\=^

!
        SET _filename=%%~ni
        FOR /F "tokens=1 delims=. " %%j IN ("!_splitpath!") DO (
            IF NOT "%%j"=="!_filename!" SET _dirname=%%j
        )

        ECHO "%%i" =^> "%_destination%\!_dirname!%%~xi"
        COPY "%%i" "%_destination%\!_dirname!%%~xi"
)

ENDLOCAL

Windows – way to copy with verification or just verify copied data

The program you've been looking for is xxcopy. I too had this desire to do a binary file compare when copying oh, a few hundred thousand files for forensic analysis. I didn't care it took a little longer, I didn't want to have to create a SFV or MD5 file and then run another program on the files afterward, I wanted something that did the DOS "fc" command on the fly.

http://xxcopy.com/xxtb_027.htm#tag_319

You want switch /V2

Have a good day.

Best Answer

Related Solutions

Batch file: Change names on files with certain extensions in multiple directories based on the directory name and copy into one directory

Windows – way to copy with verification or just verify copied data

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