Q75634: Percent Signs Stripped from Batch File Text

Article: Q75634
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:3.x,4.x,5.x,6.0,6.2,6.21,6.22
Operating System(s): 
Keyword(s): 
Last Modified: 17-DEC-2000

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The information in this article applies to:

- Microsoft MS-DOS operating system versions 3.1, 3.2, 3.21, 3.3, 3.3a, 4.0, 4.01, 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
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SUMMARY
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Using a percent sign (%) in a batch file requires that two percent signs (%%) be
specified.

For example, the command to display "5%" from a batch file would be :

  ECHO 5%%

MORE INFORMATION
================

MS-DOS uses %1, %2, ... %9 as replaceable command line parameters. For example,
before executing the command ECHO %1, %1 will be replaced with the first
parameter passed to the batch file. %0 is replaced with the command used to
execute the batch file.

A single percent sign on a line is treated as a "nul" character in a batch file.
For example:

  ECHO %     is processed as ECHO
  ECHO a%b   is processed as ECHO ab

If a command contains two percent signs, MS-DOS will treat any characters between
them as an environment variable to be expanded. For example, if the SET command
shows that the current environment variables are

  COMSPEC=C:\COMMAND.COM
  PATH=C:\DOS
  PROMPT=$P$G
  B=C

then

  ECHO %PATH%     is processed as ECHO C:\DOS
  ECHO a%b%       is processed as ECHO aC
  ECHO a%b b%a    is processed as ECHO aa

If there are no characters between the two percent signs, one percent sign is
stripped off and the other will remain. This is why a FOR command that echos the
name of each file with a .COM extension would be

  FOR %V IN (*.COM) DO ECHO %V

but if the same command is placed in a batch file, the following is required:

  FOR %%V IN (*.COM) DO ECHO %%V

Reference(s):

"Microsoft MS-DOS Batch File Quick Reference," Microsoft Press.

Additional query words: 6.22 3.20 3.21 3.30 3.30a 4.00 4.01 4.01a 5.00 5.00a 6.00 6.20

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Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS321 kbMSDOS400 kbMSDOS320 kbMSDOS330a kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS310 kbMSDOS500 kbMSDOS330 kbMSDOS401 kbMSDOS500a
Version           : MS-DOS:3.x,4.x,5.x,6.0,6.2,6.21,6.22

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