Question

I am making a program that automatically backs up files, stores up to a maximum of five of them, and has an option to restore any of the five files. When the files are backed up, it adds a date and time stamp in the format of YYYYMMDD_HHMMSS_filename.ext. In order to restore the file, it is necessary to first cut out the date stamp.
The method I am currently using to cut the date stamp off of the beginning of the file is as follows.

set VAR=%VAR:~16%
echo %VAR%

The problem being, if the backed up file is called “20120825_140343_file name.txt”, the above method will only return “file,” omitting anything after the space. The spaces in the file names need to be preserved for them to be recognized by the program using them.

tl;dr I need to cut the string 20120825_140343_file name.txt into just “file name.txt”, but my method just returns “file.”

If delimiters or something would help I could separate the date stamp and file name with a different character, I.E. 20120825_140343-file-name.txt

Answer 1

Your method, though inelegant and inflexible, should work. This tells me that you are not storing the entire filename in VAR. That is why %var:~16% only results in file, and not file name.txt. I assume that you assign VAR like this somewhere:

SET VAR=%1

You’ll need to either do this:

SET VAR=%1 %2

Or insert double-quotes around the file name when you call your batch file, and then set var like this to remove the quotes:

SET VAR=%~1

That should be enough to get your batch to work.

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But, to answer the question you actually asked, I’ll show you a method of extracting “file name.txt” from var that will work even if there are more or even less than 16 prefix characters.

Use the for /f statement, specify the 3rd token, with underscores as a delimiter. Here is a self-contained example. (To run from the command-line, change %%x to %x.

SET VAR=20120825_140343_file name.txt
for /f "tokens=3 delims=_" %%x in ("%VAR%") do set VAR=%%x
ECHO %VAR%

Just remember, this solution will NOT fix your problem if you do not fix your code to assure your VAR variable has the entire filename in it.