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Using a percent sign (%) in a batch file requires that two percent signs (%%) be specified.
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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.