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I realize this isn't strictly a programming question, but I have a file with the extension .bak, and the file starts with "TAPE". What program produced this?

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migrated from Dec 6 '09 at 6:20

This question came from our site for professional and enthusiast programmers.

The file is in Microsoft Tape Format (MTF). It can be a backup of a Microsoft SQL Server's database.

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I recently received a file that matches this description. Further investigation suggests it was produced by Microsoft SQL Server's backup command.

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The extension .bak is commonly used by multiple programs and persons to indicate a backup of some kind. Since multiple sources could create the backup the file extension is not enough to identify the contents.

You could try opening the file in notepad and checking for a Magic Number.

Sometimes it's a direct copy of a file (readme.txt -> readme.bak) In this case I prefer to append the .bak extension instead of removing the existing one (readme.txt.bak)

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One of many programs could have produced it. The file extension .bak means "backup". What directory is it in? That may be a clue.

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Probably this one here:

#include <stdio.h>
int main (void) {
    FILE *fh = fopen ("TAPExxx.bak", "w");
    if (fh != NULL)
        fclose (fh);
    return 0;

Seriously, it could be any program :-)

But, since this is not actually programming related, it belongs over on SU.

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