67 lines
2.4 KiB
Plaintext
67 lines
2.4 KiB
Plaintext
@c This is part of the paxutils manual.
|
|
@c Copyright (C) 2005 Free Software Foundation, Inc.
|
|
@c Written by Sergey Poznyakoff
|
|
@c This file is distributed under GFDL 1.1 or any later version
|
|
@c published by the Free Software Foundation.
|
|
|
|
A @dfn{snapshot file} (or @dfn{directory file}) is created during
|
|
incremental backups (@pxref{Incremental Dumps}). It
|
|
contains the status of the file system at the time of the dump and is
|
|
used to determine which files were modified since the last backup.
|
|
|
|
@GNUTAR{} version @value{VERSION} supports two snapshot file
|
|
formats. The first format, called @dfn{format 0}, is the one used by
|
|
@GNUTAR{} versions up to 1.15.1. The second format, called @dfn{format
|
|
1} is an extended version of this format, that contains more metadata
|
|
and allows for further extensions.
|
|
|
|
@samp{Format 0} snapshot file begins with a line containing a
|
|
decimal number that represents the UNIX timestamp of the beginning of
|
|
the last archivation. This line is followed by directory metadata
|
|
descriptions, one per line. Each description has the following format:
|
|
|
|
@smallexample
|
|
[@var{nfs}]@var{dev} @var{inode} @var{name}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where optional @var{nfs} is a single plus character (@samp{+}) if this
|
|
directory is located on an NFS-mounted partition, @var{dev} and
|
|
@var{inode} are the device and inode numbers of the directory, and
|
|
@var{name} is the directory name.
|
|
|
|
@samp{Format 1} snapshot file begins with a line specifying the
|
|
format of the file. This line has the following structure:
|
|
|
|
@smallexample
|
|
@samp{GNU tar-}@var{tar-version}@samp{-}@var{incr-format-version}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{tar-version} is the version of @GNUTAR{} implementation
|
|
that created this snapshot, and @var{incr-format-version} is the
|
|
version number of the snapshot format (in this case @samp{1}).
|
|
|
|
The following line contains two decimal numbers, representing the
|
|
time of the last backup. First number is the number of seconds, the
|
|
second one is the number of nanoseconds, since the beginning of the
|
|
epoch.
|
|
|
|
Following lines contain directory metadata, one line per
|
|
directory. The line format is:
|
|
|
|
@smallexample
|
|
[@var{nfs}]@var{mtime-sec} @var{mtime-nsec} @var{dev} @var{inode} @var{name}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{mtime-sec} and @var{mtime-nsec} represent the last
|
|
modification time of this directory with nanosecond precision;
|
|
@var{nfs}, @var{dev}, @var{inode} and @var{name} have the same meaning
|
|
as with @samp{format 0}.
|
|
|
|
|
|
@c End of snapshot.texi
|
|
|
|
|