Hello, Windows Explorer is updating the CTIME time stamp of files even if the contents are not modified. While doing differential \ incremental tar archives under Cygwin, this becomes a problem as unmodified files are introduced to the tar archive. For example, opening and closing a MS Office document or opening and closing a text file with notepad updates CTIME. This happens even if the files are not modified.
Here is how to reproduce the issue : During a Cygwin session, let's create a simple text file : $ echo 123 > testfile.txt Administrator@orion ~ $ stat testfile.txt File: 'testfile.txt' Size: 4 Blocks: 1 IO Block: 65536 regular file Device: bc73cfd9h/3161706457d Inode: 4503599627418701 Links: 1 Access: (0644/-rw-r--r--) Uid: (197108/Administrator) Gid: (197121/ None) Access: 2016-05-26 23:34:14.437500000 +0300 Modify: 2016-05-26 23:34:14.437500000 +0300 Change: 2016-05-26 23:34:14.437500000 +0300 Birth: 2016-05-26 23:34:14.437500000 +0300 One minute later, opening and closing testfile.txt with notepad and checking the time stamps. The content of the text file is not modified : Administrator@orion ~ $ stat testfile.txt File: 'testfile.txt' Size: 4 Blocks: 1 IO Block: 65536 regular file Device: bc73cfd9h/3161706457d Inode: 4503599627418701 Links: 1 Access: (0644/-rw-r--r--) Uid: (197108/Administrator) Gid: (197121/ None) Access: 2016-05-26 23:35:36.953125000 +0300 Modify: 2016-05-26 23:34:14.437500000 +0300 Change: 2016-05-26 23:35:35.156250000 +0300 Birth: 2016-05-26 23:34:14.437500000 +0300 CTIME ( Change ) is updated. tar will add again this file to the next incremental \ differential archive because both CTIME and MTIME are checked by tar. Kindly, could it be possible to add a new option to tar to ignore CTIME on demand while creating incremental \ differential archives? The implementation of this option can be probably reflected to Cygwin and the problem can be solved.
