UTMPDUMP(1)                     User Commands                    UTMPDUMP(1)

NAME         top

       utmpdump - dump UTMP and WTMP files in raw format

SYNOPSIS         top

       utmpdump [options] [filename]

DESCRIPTION         top

       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         top

       -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         top

       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.

BUGS         top

       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.

AUTHOR         top

       Michael Krapp

SEE ALSO         top

       last(1), w(1), who(1), utmp(5)

AVAILABILITY         top

       The utmpdump command is part of the util-linux package and is
       available from Linux Kernel Archive 

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
       ⟨⟩.  If you have a
       bug report for this manual page, send it to  This page was obtained from the
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       ⟨git://⟩ on
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util-linux                        July 2014                      UTMPDUMP(1)

Pages that refer to this page: getutmp(3)utmp(5)