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Copyright (C) 2010 Michael Krapp
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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= utmpdump(1)
:doctype: manpage
:man manual: User Commands
:man source: util-linux {release-version}
:page-layout: base
:command: utmpdump
== NAME
utmpdump - dump UTMP and WTMP files in raw format
== SYNOPSIS
*utmpdump* [options] _filename_
== DESCRIPTION
*utmpdump* is a simple program to dump UTMP and WTMP files in raw format, so they can be examined. *utmpdump* reads from stdin unless a _filename_ is passed.
== OPTIONS
*-f*, *--follow*::
Output appended data as the file grows.
*-o*, *--output* _file_::
Write command output to _file_ instead of standard output.
*-r*, *--reverse*::
Undump, write back edited login information into the utmp or wtmp files.
*-V*, *--version*::
Display version information and exit.
*-h*, *--help*::
Display help text and exit.
== NOTES
*utmpdump* can be useful in cases of corrupted utmp or wtmp entries. It can dump out utmp/wtmp to an ASCII file, which can then be edited to remove bogus entries, and reintegrated using:
____
*utmpdump -r < ascii_file > wtmp*
____
But be warned, *utmpdump* was written for debugging purposes only.
=== File formats
Only the binary version of the *utmp*(5) is standardised. Textual dumps may become incompatible in future.
The version 2.28 was the last one that printed text output using *ctime*(3) timestamp format. Newer dumps use millisecond precision ISO-8601 timestamp format in UTC-0 timezone. Conversion from former timestamp format can be made to binary, although attempt to do so can lead the timestamps to drift amount of timezone offset.
== BUGS
You may *not* use the *-r* option, as the format for the utmp/wtmp files strongly depends on the input format. This tool was *not* written for normal use, but for debugging only.
== AUTHORS
Michael Krapp
== SEE ALSO
*last*(1),
*w*(1),
*who*(1),
*utmp*(5)
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