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
       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.

       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-

util-linux                         July 2014                       UTMPDUMP(1)