st_atim Time when file data was last accessed. Changed
implicitly by syscalls such as read(2) and readv(2), and
explicitly by utimes(2).
st_mtim Time when file data was last modified. Changed
implicitly by syscalls such as truncate(2), write(2),
and writev(2), and explicitly by utimes(2). Also, any
syscall which modifies directory content changes the
st_mtim for the affected directory. For instance,
creat(2), mkdir(2), rename(2), link(2), and unlink(2).
st_ctim Time when file status was last changed (inode data
modification). Changed implicitly by any syscall that
affects file metadata, including st_mtim, such as
chflags(2), chmod(2), chown(2), truncate(2), utimes(2),
and write(2). Also, any syscall which modifies
directory content changes the st_ctim for the affected
directory. For instance, creat(2), mkdir(2), rename(2),
link(2), and unlink(2).