utmpdump(1) 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.


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


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