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.
Output appended data as the file grows.
-o, --output file
Write command output to file instead of standard
Undump, write back edited login information into the utmp
or wtmp files.
Display version information and exit.
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 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.