Graham Williams
2008-Dec-19 09:13 UTC
[R] Does file.info man page describe ctime corrrectly?
(R 2.8.0 on Debian GNU/Linux sid) ?file.info contains: mtime, ctime, atime: integer of class '"POSIXct"': file modification, creation and last access times. This implies that ctime is "file [...] creation [...] time" Has R implemented ctime differently to Unix? I understand, on Linux at least, that ctime is the last change time (not the creation time). See "man ls" which says: -c [...] ctime (time of last modification of file status information) [...] However, testing seems to indicate file.info is returning the change time, not creation time (I'm not sure we can actually determine creation time of a file on Linux). Perhaps just a file.info documentation slip? Regards, Graham
Prof Brian Ripley
2008-Dec-19 09:47 UTC
[R] Does file.info man page describe ctime corrrectly?
This really is a topic for R-devel ... see the posting guide. On Fri, 19 Dec 2008, Graham Williams wrote:> (R 2.8.0 on Debian GNU/Linux sid) > > ?file.info contains: > > mtime, ctime, atime: integer of class '"POSIXct"': file modification, > creation and last access times. > > This implies that ctime is "file [...] creation [...] time" > > Has R implemented ctime differently to Unix? > > I understand, on Linux at least, that ctime is the last change time > (not the creation time). See "man ls" which says: > > -c [...] ctime (time of last modification of file status > information) [...]'man stat' would be more definitive, and http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap04.html#tag_04_07 even more so (but only for POSIX-compliant OSes). As you will see, there is considerable room for interpretation even under POSIX.> However, testing seems to indicate file.info is returning the change > time, not creation time (I'm not sure we can actually determine > creation time of a file on Linux). > > Perhaps just a file.info documentation slip?Well, to call it 'last change' would indeed be a documentation slip. What it does depends on the OS and file system, but on Linux it is the last *status* change, which is often the creation time (modifying the file does not necessarily change the status). On Windows it *is* the creation time, and that means it is too on a SMB-mounted Windows file system on Linux. -- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595