{
    "mode": "man",
    "parameter": "E4DEFRAG",
    "section": "8",
    "url": "https://www.chedong.com/phpMan.php/man/E4DEFRAG/8/json",
    "generated": "2026-10-06T09:46:23Z",
    "synopsis": "e4defrag [ -c ] [ -v ] target ...",
    "sections": {
        "NAME": {
            "content": "e4defrag - online defragmenter for ext4 file system\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "e4defrag [ -c ] [ -v ] target ...\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "e4defrag reduces fragmentation of extent based file. The file targeted by e4defrag is created\non  ext4  file  system  made with \"-O extent\" option (see mke2fs(8)).  The targeted file gets\nmore contiguous blocks and improves the file access speed.\n\ntarget is a regular file, a directory, or a device that is mounted as ext4 file  system.   If\ntarget  is a directory, e4defrag reduces fragmentation of all files in it. If target is a de‐\nvice, e4defrag gets the mount point of it and reduces fragmentation  of  all  files  in  this\nmount point.\n",
            "subsections": []
        },
        "OPTIONS": {
            "content": "",
            "subsections": [
                {
                    "name": "-c",
                    "content": "fragmentation score based on them. By seeing this score, we can determine  whether  we\nshould  execute  e4defrag to target.  When used with -v option, the current fragmenta‐\ntion count and the ideal fragmentation count are printed for each file.\n\nAlso this option outputs the average data size in one extent. If you  see  it,  you'll\nfind  the file has ideal extents or not. Note that the maximum extent size is 131072KB\nin ext4 file system (if block size is 4KB).\n\nIf this option is specified, target is never defragmented.\n",
                    "flag": "-c"
                },
                {
                    "name": "-v",
                    "content": "file.\n",
                    "flag": "-v"
                }
            ]
        },
        "NOTES": {
            "content": "e4defrag  does  not  support swap file, files in lost+found directory, and files allocated in\nindirect blocks. When target is a device or a mount point, e4defrag doesn't defragment  files\nin mount point of other device.\n\nIt  is  safe  to  run  e4defrag on a file while it is actively in use by another application.\nSince the contents of file blocks are copied using the page cache, this can result in a  per‐\nformance  slowdown  to  both e4defrag and the application due to contention over the system's\nmemory and disk bandwidth.\n\nIf the file system's free space is fragmented, or if there is insufficient free space  avail‐\nable, e4defrag may not be able to improve the file's fragmentation.\n\nNon-privileged  users can execute e4defrag to their own file, but the score is not printed if",
            "subsections": [
                {
                    "name": "-c",
                    "content": "",
                    "flag": "-c"
                }
            ]
        },
        "AUTHOR": {
            "content": "Written by Akira Fujita <a-fujita@rs.jp.nec.com> and Takashi Sato <t-sato@yk.jp.nec.com>.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "mke2fs(8), mount(8).\n\n\ne4defrag version 2.0                          May 2009                                   E4DEFRAG(8)",
            "subsections": []
        }
    },
    "summary": "e4defrag - online defragmenter for ext4 file system",
    "flags": [
        {
            "flag": "-c",
            "long": null,
            "arg": null,
            "description": "fragmentation score based on them. By seeing this score, we can determine whether we should execute e4defrag to target. When used with -v option, the current fragmenta‐ tion count and the ideal fragmentation count are printed for each file. Also this option outputs the average data size in one extent. If you see it, you'll find the file has ideal extents or not. Note that the maximum extent size is 131072KB in ext4 file system (if block size is 4KB). If this option is specified, target is never defragmented."
        },
        {
            "flag": "-v",
            "long": null,
            "arg": null,
            "description": "file."
        }
    ],
    "examples": [],
    "see_also": [
        {
            "name": "mke2fs",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/mke2fs/8/json"
        },
        {
            "name": "mount",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/mount/8/json"
        }
    ]
}