Section: User Commands (1)
Updated: July 2014
utmpdump - dump UTMP and WTMP files in raw format
is a simple program to dump UTMP and WTMP files in raw format, so they
can be examined.
reads from stdin unless a
- -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.
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,
was written for debugging purposes only.
Only the binary version of the
is standardised. Textual dumps may become incompatible in future.
The version 2.28 was the last one that printed text output using
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.
option, as the format for the utmp/wtmp files strongly depends on the input
format. This tool was
written for normal use, but for debugging only.
The utmpdump command is part of the util-linux package and is available
Linux Kernel Archive