{
    "mode": "man",
    "parameter": "utmpdump",
    "section": "1",
    "url": "https://www.chedong.com/phpMan.php/man/utmpdump/1/json",
    "generated": "2026-05-30T05:11:45Z",
    "synopsis": "utmpdump [options] filename",
    "sections": {
        "NAME": {
            "content": "utmpdump - dump UTMP and WTMP files in raw format\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "utmpdump [options] filename\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "utmpdump is a simple program to dump UTMP and WTMP files in raw format, so they can be\nexamined. utmpdump reads from stdin unless a filename is passed.\n",
            "subsections": []
        },
        "OPTIONS": {
            "content": "",
            "subsections": [
                {
                    "name": "-f --follow",
                    "content": "Output appended data as the file grows.\n",
                    "flag": "-f",
                    "long": "--follow"
                },
                {
                    "name": "-o --output",
                    "content": "Write command output to file instead of standard output.\n",
                    "flag": "-o",
                    "long": "--output"
                },
                {
                    "name": "-r --reverse",
                    "content": "Undump, write back edited login information into the utmp or wtmp files.\n",
                    "flag": "-r",
                    "long": "--reverse"
                },
                {
                    "name": "-V --version",
                    "content": "Display version information and exit.\n",
                    "flag": "-V",
                    "long": "--version"
                },
                {
                    "name": "-h --help",
                    "content": "Display help text and exit.\n",
                    "flag": "-h",
                    "long": "--help"
                }
            ]
        },
        "NOTES": {
            "content": "utmpdump can be useful in cases of corrupted utmp or wtmp entries. It can dump out utmp/wtmp\nto an ASCII file, which can then be edited to remove bogus entries, and reintegrated using:\n\nutmpdump -r < asciifile > wtmp\n\nBut be warned, utmpdump was written for debugging purposes only.\n",
            "subsections": [
                {
                    "name": "File formats",
                    "content": "Only the binary version of the utmp(5) is standardised. Textual dumps may become incompatible\nin future.\n\nThe version 2.28 was the last one that printed text output using ctime(3) timestamp format.\nNewer dumps use millisecond precision ISO-8601 timestamp format in UTC-0 timezone. Conversion\nfrom former timestamp format can be made to binary, although attempt to do so can lead the\ntimestamps to drift amount of timezone offset.\n"
                }
            ]
        },
        "BUGS": {
            "content": "You may not use the -r option, as the format for the utmp/wtmp files strongly depends on the\ninput format. This tool was not written for normal use, but for debugging only.\n",
            "subsections": []
        },
        "AUTHORS": {
            "content": "Michael Krapp\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "last(1), w(1), who(1), utmp(5)\n",
            "subsections": []
        },
        "REPORTING BUGS": {
            "content": "For bug reports, use the issue tracker at https://github.com/karelzak/util-linux/issues.\n",
            "subsections": []
        },
        "AVAILABILITY": {
            "content": "The utmpdump command is part of the util-linux package which can be downloaded from Linux\nKernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.\n\n\n\nutil-linux 2.37.2                            2021-06-02                                  UTMPDUMP(1)",
            "subsections": []
        }
    },
    "summary": "utmpdump - dump UTMP and WTMP files in raw format",
    "flags": [
        {
            "flag": "-f",
            "long": "--follow",
            "arg": null,
            "description": "Output appended data as the file grows."
        },
        {
            "flag": "-o",
            "long": "--output",
            "arg": null,
            "description": "Write command output to file instead of standard output."
        },
        {
            "flag": "-r",
            "long": "--reverse",
            "arg": null,
            "description": "Undump, write back edited login information into the utmp or wtmp files."
        },
        {
            "flag": "-V",
            "long": "--version",
            "arg": null,
            "description": "Display version information and exit."
        },
        {
            "flag": "-h",
            "long": "--help",
            "arg": null,
            "description": "Display help text and exit."
        }
    ],
    "examples": [],
    "see_also": [
        {
            "name": "last",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/last/1/json"
        },
        {
            "name": "w",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/w/1/json"
        },
        {
            "name": "who",
            "section": "1",
            "url": "https://www.chedong.com/phpMan.php/man/who/1/json"
        },
        {
            "name": "utmp",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/utmp/5/json"
        }
    ]
}