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.

AUTHOR

       Michael Krapp

SEE ALSO

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

AVAILABILITY

       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/⟩.