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.
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 email@example.com. This page was obtained from the project's upstream Git repository ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on 2020-07-14. (At that time, the date of the most recent commit that was found in the repository was 2020-07-14.) If you discover any rendering problems in this HTML version 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 manual page), send a mail to firstname.lastname@example.org util-linux July 2014 UTMPDUMP(1)
Pages that refer to this page: getutmp(3), getutmpx(3), utmp(5), utmpx(5), wtmp(5)