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 Windows NT 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 Windows NT to copy data to the device in ASCII mode. In ASCII
mode, such special characters as those previously listed may cause Windows NT to
take special action during the copying process, such as
Using the default destination file
If you do not specify a destination file, Windows NT 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 Windows NT displays the following error message:
File cannot be copied onto itself
0 File(s) copied
Using the /v switch
If Windows NT 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 Windows NT 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.
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. 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+,,
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