Conditional processing symbols allow you to control the execution of commands; allowing you to issue multiple commands from the same prompt and to govern program flow based on the results of a command. Using these in special ways allow you to extend the command prompt rules. These symbols may not be part of a file name. Note that filenames and extensions can be up to 256 characters long under Windows NT/2000/XP.
The conditional processing symbols are: " * : / \ ? < >
For a complete description of conditional symbols, use the system Help (Help and Support under Windows XP) using keyword: conditional. Extensions of the command processor, CMD.EXE over COMMAND.COM are described under Help and Support keyword: CMD. General commands are described under Help and Support keyword: commands. Under Windows XP after doing this, click the "Full text search matches" bar at the bottom of the results screen.
Therefore under Windows NT/2000/XP Command Prompt, the rules are slightly different than under Windows 9x or DOS. For example, one of these differences is that an Ampersand (&) is a special character under NT/2000/XP Command Prompt (or START/RUN) command lines. In particular, & is used to separate commands and so cannot simply appear as an option to a command.
For example, the command:
PKZIP -a -ex -& a:\Zipfile.zip c:\FilesToZip
works under all Windows 9x MS-DOS Prompt (or START/RUN) but would fail under Windows NT/2000/XP Command Prompt; in the latter case, preceed it with a caret (^). For example:
PKZIP -a -ex -^& a:\Zipfile.zip C:\FilesToZip
When writing Batch files this must be taken into consideration.
For example, to run the above DOS PKZIP command via a .BAT file that will run under Windows NT/2000/XP Command Prompt or any other Windows DOS (prompt), one could write the DOS Batch file:
@Echo off REM Environment variable OS is set for Windows NT. if NOT "%OS%" == "Windows_NT" GoTo NotNT Echo this is Windows NT PKZIP -a -ex -^& a:\ZipFile.ZIP C:\FilesToZip GoTo Next :NotNT Echo this is NOT Windows NT PKZIP -a -ex -& a:\ZipFile.ZIP C:\FilesToZip
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