COPY--Notes
 
Setting the COPYCMD environment variable
 
You can set the COPYCMD environment variable to specify whether you want the
COPY, MOVE, and XCOPY commands to prompt you for confirmation before
overwriting a file, whether issued from the command prompt or a batch file.
 
To force the COPY, MOVE, and XCOPY commands to prompt you before overwriting
in all cases, set the COPYCMD environment variable /-Y. To force these
commands to overwrite in all cases without prompting you, set the COPYCMD
environment variable to /Y.
 
Typing any of these commands with the /Y or /-Y switch overrides all
defaults and the current setting of the COPYCMD environment variable.
 
Copying to and from devices
 
You can substitute a device name for one or more occurrences of source or
for destination.
 
Using or omitting the /B switch when copying to a device
 
When destination is a device (for example, COM1 or LPT1), the /B switch
causes MS-DOS to copy data to the device in binary mode. In binary mode, all
characters (including such special characters as CTRL+C, CTRL+S, CTRL+Z, and
carriage return) are copied to the device as data. Whereas, omission of the
/B switch causes MS-DOS to copy data to the device in ASCII mode. In ASCII
mode, such special characters as those previously listed may cause MS-DOS to
take special action during the copying process.
 
Using the default destination file
 
If you do not specify a destination file, MS-DOS creates a copy with the
same name, creation date, and creation time as the original file, placing
the new copy in the current directory on the current drive. If the source
file is on the current drive and in the current directory and you do not
specify a different drive or directory for the destination file, the COPY
command stops and MS-DOS displays the following error message:
 
    File cannot be copied onto itself
    0 File(s) copied
 
Using the /V switch
 
If MS-DOS cannot verify a write operation, it displays an error message.
Although recording errors rarely occur with the COPY command, the /V switch
lets you verify that critical data has been correctly recorded. The /V
switch also slows down the COPY command, because MS-DOS must check each
sector recorded on the disk.
 
Using the /A and /B switches
 
The effect of an /A or /B switch depends upon its position on the command
line. When the /A or /B switch follows the source filename, COPY performs as
shown in the following list:
 
/A
    Treats the file as an ASCII (text) file and copies data that precedes
    the first end-of-file character. COPY does not copy the first
    end-of-file character or the remainder of the file.
 
/B
    Copies the entire file, including any end-of-file character.
 
When the /A or /B switch follows the destination filename, COPY performs as
shown in the following list:
 
/A
    Adds an end-of-file character as the last character of the file.
 
/B
    Does not add an end-of-file character.
 
Combining files with the COPY command
 
If you specify more than one source, separating entries with a plus sign
(+), COPY combines the files, creating a single file. If you use wildcards
in source but specify a single filename in destination, COPY combines all
files matching the filename in source and creates a single file with the
filename specified in destination.
 
In either case, COPY assumes the combined files are ASCII files unless you
specify the /B switch. (Do not combine non-ASCII files without specifying
the /B switch; doing so can result in truncated files, since most binary
files contain CTRL+Z characters which cause COPY to behave as if it has
reached the end of the file.)
 
If the name of the destination file is the same as the name of one of the
files being copied (except the first file), the original contents of the
destination file are lost. When this happens, COPY displays the following
message:
 
    Content of destination lost before copy
 
Copying files in subdirectories
 
To copy all of a directory's files and subdirectories, you should use the
XCOPY command.
 
Copying zero-length files
 
COPY does not copy files that are 0 bytes long; instead, it deletes such
files. Use XCOPY to copy these files.
 
Changing the time and date of a file
 
If you want to assign the current time and date to a file without modifying
the file, use a command in the following format. The commas indicate the
omission of the destination parameter.
 
    copy /b source+,,