![]() The script empty.cmd will show if the folder is empty or not (this is not case sensitive). IF EXIST filename Will detect the existence of a file or a folder. To test for the existence of a variable use SET VariableName, or IF DEFINED VariableName Test the existence of files and folders IF DEFINED will return true if the variable contains any value (even if the value is just a space). IF NOT DEFINED _example ECHO Value Missing In the case of a variable that might be NULL - a null variable will remove the variable definition altogether, so testing for a NULL becomes: However with this pattern if %_myvar% does unexpectedly contain quotes, you will get IF ""C:\Some Path"" EQU "" those doubled quotes, while not officially documented as an escape will still mess up the comparison. If %_myvar% will never contain quotes, then you can use quotes in place of the brackets IF "%_myvar%" EQU "" If %_myvar% could contain empty quotes, "" then your comparison should become IF EQU When working with filenames/paths you should always surround them with quotes, if %_myvar% contains "C:\Some Path" then your comparison becomes IF EQU You can in fact use almost any character for this a '~' or curly brackets, or even the number 4, but square brackets tend to be chosen because they don’t have any special meaning. When comparing against a variable that may be empty, we include a pair of brackets so that if the variable does happen to be empty the IF command still has something to compare: IF EQU will return True. To test for the existence of a command line parameter - use empty brackets like this: If present such a variable will override and prevent the system variable %ERRORLEVEL% from being read by commands such as ECHO and IF. It is possible (though not a good idea) to create a string variable called %ERRORLEVEL% (user variable) To deliberately raise an ERRORLEVEL in a batch script use the EXIT /B command. This allows you to trap errors that can be negative numbers, you can also test for specific errors: IF %ERRORLEVEL% EQU 0 Echo No error found || Echo An error was found IF %ERRORLEVEL% EQU 0 (Echo No error found) ELSE (Echo An error was found) IF %ERRORLEVEL% EQU 0 Echo No error found IF %ERRORLEVEL% NEQ 0 Echo An error was found Using the %ERRORLEVEL% variable is a more logical method of checking Errorlevels: This is not very readable or user friendly and does not easily account for negative error numbers. IF NOT ERRORLEVEL 1 means if ERRORLEVEL is less than 1 (Zero or negative). ![]() IF ERRORLEVEL 1 will return TRUE whether the errorlevel is 1 or 5 or 64 IF ERRORLEVEL 0 will return TRUE whether the errorlevel is 0, 1 or 5 or 64 This 3 digit syntax is necessary because the > and = number I Do a case Insensitive string comparison. = Perform the command if the two strings are equal. NOT Perform the command if the condition is false. IF CMDEXTVERSION number command key item A text string or environment variable, for more complexĬomparisons, a variable can be modified usingįilename A file to test or a wildcard pattern. IF item1 compare-op item2 ( command) ELSE ( command) IF EXIST filename ( command) ELSE ( command) Just for the record, I did in fact read the "great Readme" file, wherein it invited people with further questions to participate in this forum.Conditionally perform a command. Perhaps someone with less of a penchant for sarcasm would like to clarify whether DosBox supports this sort of an operation, and if so, what sort of syntax is needed to distinguish parameters that are intended to be passed to the file to be run, from command line parameters that are intended for DosBox itself. So, I would like to rework the macro so that it calls DosBox, which would in turn run the external program, but I still need to pass the file referenced in the spread sheet as an argument to the invoked program. Works fine in Win98, but the external program that is being invoked won't run under more recent versions of Windows. That program is passed a file name argument obtained from the spreadsheet cell that has the focus when the macro is run. I have a spreadsheet that contains a macro which uses the Visual Basis shell() function to run an external program. Evidently I need to elaborate on what I'm trying to do. ![]()
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