On Thu, Jan 16, 2020 at 01:16:47PM +0100, Otto Moerbeek wrote: > On Thu, Jan 16, 2020 at 11:20:10AM +0000, gritzmann wrote: > > > Hi, > > > > How do I change the birth time of a file? `touch -acm -d "1980-01-01 > > 00:00:00" myfile` changes only the access, modify and change times. > > > > `stat myfile` returns `10 215746 -rw-r--r-- 1 me me 0 0 "Jan 1 00:00:00 > > 1980" "Jan 1 00:00:00 1980" "Jan 16 13:00:33 2020" 16384 0 0 myfile` > > > > Thanks! > > > > Sent with ProtonMail Secure Email. > > > > Change time != creation time. There is no such thing as creation time > in unix.
Not in Unix, but with UFS2 FreeBSD added birth time, which is documented everywhere--including in source code--as being synonymous with "creation time". OpenBSD added the st_birthtime field to struct stat in 2004, https://cvsweb.openbsd.org/src/sys/sys/stat.h?rev=1.14&content-type=text/x-cvsweb-markup https://github.com/openbsd/src/commit/cc2fc615c6e2dee87e5a3cd5a655a2ee5ef778c8 but as far as I can tell it's not set anywhere in the kernel. FWIW, birth time has been adopted by ext4, ZFS, AFS, HAMMER2, and possibly other file systems, but only the *BSDs seem to have added st_birthtime in struct stat. On Linux it's stx_btime in struct statx, and as best I can tell Solaris requires querying the A_CRTIME (creation time?) attribute using getattrat. None of this is particularly relevant to OpenBSD, and I don't mean to advocate, but after having done the leg work I feel like I should commit this to an archive for posterity... > The change time (c_time in struct stat) cannot be explicitly set by > any API and is maintained by the kernel. As far as I can tell from the FreeBSD man page for utimes and friends, this is likewise true for birth time.
