login-utils/utmpdump.1

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  17 .TH UTMPDUMP 1 "July 2014" "util-linux" "User Commands"
  18 .SH NAME
  19 utmpdump \- dump UTMP and WTMP files in raw format
  20 .SH SYNOPSIS
  21 .BR utmpdump " [options]"
  22 .RI [ filename ]
  23 .SH DESCRIPTION
  24 .B utmpdump
  25 is a simple program to dump UTMP and WTMP files in raw format, so they
  26 can be examined.
  27 .B utmpdump
  28 reads from stdin unless a
  29 .I filename
  30 is passed.
  31 .SH OPTIONS
  32 .TP
  33 .BR \-f , " \-\-follow"
  34 Output appended data as the file grows.
  35 .TP
  36 .BR \-o , " \-\-output " \fIfile
  37 Write command output to \fIfile\fR instead of standard output.
  38 .TP
  39 .BR \-r , " \-\-reverse"
  40 Undump, write back edited login information into the utmp or wtmp files.
  41 .TP
  42 .BR \-V , " \-\-version"
  43 Display version information and exit.
  44 .TP
  45 .BR \-h , " \-\-help"
  46 Display help text and exit.
  47 .SH NOTES
  48 .B utmpdump
  49 can be useful in cases of corrupted utmp or wtmp entries.  It can dump
  50 out utmp/wtmp to an ASCII file, which can then be edited to remove
  51 bogus entries, and reintegrated using:
  52 .PP
  53 .RS
  54 .B utmpdump \-r < ascii_file > wtmp
  55 .RE
  56 .PP
  57 But be warned,
  58 .B utmpdump
  59 was written for debugging purposes only.
  60 .SS File formats
  61 .PP
  62 Only the binary version of the
  63 .BR utmp (5)
  64 is standardised.  Textual dumps may become incompatible in future.
  65 .PP
  66 The version 2.28 was the last one that printed text output using
  67 .BR ctime (3)
  68 timestamp format.  Newer dumps use millisecond precision ISO-8601 timestamp
  69 format in UTC-0 timezone.  Conversion from former timestamp format can be
  70 made to binary, although attempt to do so can lead the timestamps to drift
  71 amount of timezone offset.
  72 .SH BUGS
  73 You may
  74 .B not
  75 use the
  76 .B \-r
  77 option, as the format for the utmp/wtmp files strongly depends on the input
  78 format.  This tool was
  79 .B not
  80 written for normal use, but for debugging only.
  81 .SH AUTHORS
  82 Michael Krapp
  83 .SH SEE ALSO
  84 .BR last (1),
  85 .BR w (1),
  86 .BR who (1),
  87 .BR utmp (5)
  88 .SH AVAILABILITY
  89 The utmpdump command is part of the util-linux package and is available
  90 from
  91 .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
  92 Linux Kernel Archive
  93 .UE .