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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | NOTES | BUGS | AUTHOR | SEE ALSO | AVAILABILITY | COLOPHON |
UTMPDUMP(1) User Commands UTMPDUMP(1)
utmpdump - dump UTMP and WTMP files in raw format
utmpdump [options] [filename]
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.
-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.
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
The only 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.
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.
Michael Krapp
last(1), w(1), who(1), utmp(5)
The utmpdump command is part of the util-linux package and is
available from Linux Kernel Archive
⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found at
⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a
bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2017-07-05. If you discover any rendering problems in this HTML ver‐
sion of the page, or you believe there is a better or more up-to-date
source for the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original man‐
ual page), send a mail to man-pages@man7.org
util-linux July 2014 UTMPDUMP(1)
Pages that refer to this page: getutmp(3), utmp(5)