{ "content": [ { "type": "text", "text": "# fsck.ext4 (info)\n\n## NAME\n\ne2fsck - check a Linux ext2/ext3/ext4 file system\n\n## SYNOPSIS\n\ne2fsck [ -pacnyrdfkvtDFV ] [ -b superblock ] [ -B blocksize ] [ -l|-L\nbadblocksfile ] [ -C fd ] [ -j external-journal ] [ -E extendedop-\ntions ] [ -z undofile ] device\n\n## DESCRIPTION\n\ne2fsck is used to check the ext2/ext3/ext4 family of file systems. For\next3 and ext4 file systems that use a journal, if the system has been\nshut down uncleanly without any errors, normally, after replaying the\ncommitted transactions in the journal, the file system should be\nmarked as clean. Hence, for file systems that use journaling, e2fsck\nwill normally replay the journal and exit, unless its superblock indi-\ncates that further checking is required.\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION**\n- **OPTIONS**\n- **EXIT CODE**\n- **SIGNALS**\n- **REPORTING BUGS**\n- **ENVIRONMENT**\n- **AUTHOR**\n- **SEE ALSO**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "fsck.ext4", "section": "", "mode": "info", "summary": "e2fsck - check a Linux ext2/ext3/ext4 file system", "synopsis": "e2fsck [ -pacnyrdfkvtDFV ] [ -b superblock ] [ -B blocksize ] [ -l|-L\nbadblocksfile ] [ -C fd ] [ -j external-journal ] [ -E extendedop-\ntions ] [ -z undofile ] device", "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [], "examples": [], "see_also": [ { "name": "e2fsck.conf", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/e2fsck.conf/5/json" }, { "name": "badblocks", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/badblocks/8/json" }, { "name": "dumpe2fs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/dumpe2fs/8/json" }, { "name": "debugfs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/debugfs/8/json" }, { "name": "e2image", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/e2image/8/json" }, { "name": "mke2fs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/mke2fs/8/json" }, { "name": "tune2fs", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/tune2fs/8/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 4, "subsections": [] }, { "name": "DESCRIPTION", "lines": 28, "subsections": [] }, { "name": "OPTIONS", "lines": 247, "subsections": [] }, { "name": "EXIT CODE", "lines": 12, "subsections": [] }, { "name": "SIGNALS", "lines": 11, "subsections": [] }, { "name": "REPORTING BUGS", "lines": 27, "subsections": [] }, { "name": "ENVIRONMENT", "lines": 4, "subsections": [] }, { "name": "AUTHOR", "lines": 2, "subsections": [] }, { "name": "SEE ALSO", "lines": 4, "subsections": [] } ], "sections": { "NAME": { "content": "e2fsck - check a Linux ext2/ext3/ext4 file system\n", "subsections": [] }, "SYNOPSIS": { "content": "e2fsck [ -pacnyrdfkvtDFV ] [ -b superblock ] [ -B blocksize ] [ -l|-L\nbadblocksfile ] [ -C fd ] [ -j external-journal ] [ -E extendedop-\ntions ] [ -z undofile ] device\n", "subsections": [] }, "DESCRIPTION": { "content": "e2fsck is used to check the ext2/ext3/ext4 family of file systems. For\next3 and ext4 file systems that use a journal, if the system has been\nshut down uncleanly without any errors, normally, after replaying the\ncommitted transactions in the journal, the file system should be\nmarked as clean. Hence, for file systems that use journaling, e2fsck\nwill normally replay the journal and exit, unless its superblock indi-\ncates that further checking is required.\n\ndevice is a block device (e.g., /dev/sdc1) or file containing the file\nsystem.\n\nNote that in general it is not safe to run e2fsck on mounted file sys-\ntems. The only exception is if the -n option is specified, and -c, -l,\nor -L options are not specified. However, even if it is safe to do\nso, the results printed by e2fsck are not valid if the file system is\nmounted. If e2fsck asks whether or not you should check a file system\nwhich is mounted, the only correct answer is ``no''. Only experts who\nreally know what they are doing should consider answering this question\nin any other way.\n\nIf e2fsck is run in interactive mode (meaning that none of -y, -n, or\n-p are specified), the program will ask the user to fix each problem\nfound in the file system. A response of 'y' will fix the error; 'n'\nwill leave the error unfixed; and 'a' will fix the problem and all sub-\nsequent problems; pressing Enter will proceed with the default re-\nsponse, which is printed before the question mark. Pressing Control-C\nterminates e2fsck immediately.\n", "subsections": [] }, "OPTIONS": { "content": "-a This option does the same thing as the -p option. It is pro-\nvided for backwards compatibility only; it is suggested that\npeople use -p option whenever possible.\n\n-b superblock\nInstead of using the normal superblock, use an alternative su-\nperblock specified by superblock. This option is normally used\nwhen the primary superblock has been corrupted. The location of\nbackup superblocks is dependent on the file system's blocksize,\nthe number of blocks per group, and features such as sparsesu-\nper.\n\nAdditional backup superblocks can be determined by using the\nmke2fs program using the -n option to print out where the su-\nperblocks exist, supposing mke2fs is supplied with arguments\nthat are consistent with the file system's layout (e.g. block-\nsize, blocks per group, sparsesuper, etc.).\n\nIf an alternative superblock is specified and the file system is\nnot opened read-only, e2fsck will make sure that the primary su-\nperblock is updated appropriately upon completion of the file\nsystem check.\n\n-B blocksize\nNormally, e2fsck will search for the superblock at various dif-\nferent block sizes in an attempt to find the appropriate block\nsize. This search can be fooled in some cases. This option\nforces e2fsck to only try locating the superblock at a particu-\nlar blocksize. If the superblock is not found, e2fsck will ter-\nminate with a fatal error.\n\n-c This option causes e2fsck to use badblocks(8) program to do a\nread-only scan of the device in order to find any bad blocks.\nIf any bad blocks are found, they are added to the bad block in-\node to prevent them from being allocated to a file or directory.\nIf this option is specified twice, then the bad block scan will\nbe done using a non-destructive read-write test.\n\n-C fd This option causes e2fsck to write completion information to the\nspecified file descriptor so that the progress of the file sys-\ntem check can be monitored. This option is typically used by\nprograms which are running e2fsck. If the file descriptor num-\nber is negative, then absolute value of the file descriptor will\nbe used, and the progress information will be suppressed ini-\ntially. It can later be enabled by sending the e2fsck process a\nSIGUSR1 signal. If the file descriptor specified is 0, e2fsck\nwill print a completion bar as it goes about its business. This\nrequires that e2fsck is running on a video console or terminal.\n\n-d Print debugging output (useless unless you are debugging\ne2fsck).\n\n-D Optimize directories in file system. This option causes e2fsck\nto try to optimize all directories, either by re-indexing them\nif the file system supports directory indexing, or by sorting\nand compressing directories for smaller directories, or for file\nsystems using traditional linear directories.\n\nEven without the -D option, e2fsck may sometimes optimize a few\ndirectories --- for example, if directory indexing is enabled\nand a directory is not indexed and would benefit from being in-\ndexed, or if the index structures are corrupted and need to be\nrebuilt. The -D option forces all directories in the file sys-\ntem to be optimized. This can sometimes make them a little\nsmaller and slightly faster to search, but in practice, you\nshould rarely need to use this option.\n\nThe -D option will detect directory entries with duplicate names\nin a single directory, which e2fsck normally does not enforce\nfor performance reasons.\n\n-E extendedoptions\nSet e2fsck extended options. Extended options are comma sepa-\nrated, and may take an argument using the equals ('=') sign.\nThe following options are supported:\n\neaver=extendedattributeversion\nSet the version of the extended attribute blocks\nwhich e2fsck will require while checking the file\nsystem. The version number may be 1 or 2. The de-\nfault extended attribute version format is 2.\n\njournalonly\nOnly replay the journal if required, but do not per-\nform any further checks or repairs.\n\nfragcheck\nDuring pass 1, print a detailed report of any dis-\ncontiguous blocks for files in the file system.\n\ndiscard\nAttempt to discard free blocks and unused inode\nblocks after the full file system check (discarding\nblocks is useful on solid state devices and sparse /\nthin-provisioned storage). Note that discard is done\nin pass 5 AFTER the file system has been fully\nchecked and only if it does not contain recognizable\nerrors. However there might be cases where e2fsck\ndoes not fully recognize a problem and hence in this\ncase this option may prevent you from further manual\ndata recovery.\n\nnodiscard\nDo not attempt to discard free blocks and unused in-\node blocks. This option is exactly the opposite of\ndiscard option. This is set as default.\n\nnooptimizeextents\nDo not offer to optimize the extent tree by elimi-\nnating unnecessary width or depth. This can also be\nenabled in the options section of /etc/e2fsck.conf.\n\noptimizeextents\nOffer to optimize the extent tree by eliminating un-\nnecessary width or depth. This is the default un-\nless otherwise specified in /etc/e2fsck.conf.\n\ninodecountfullmap\nTrade off using memory for speed when checking a\nfile system with a large number of hard-linked\nfiles. The amount of memory required is propor-\ntional to the number of inodes in the file system.\nFor large file systems, this can be gigabytes of\nmemory. (For example, a 40TB file system with 2.8\nbillion inodes will consume an additional 5.7 GB\nmemory if this optimization is enabled.) This opti-\nmization can also be enabled in the options section\nof /etc/e2fsck.conf.\n\nnoinodecountfullmap\nDisable the inodecountfullmap optimization. This\nis the default unless otherwise specified in\n/etc/e2fsck.conf.\n\nreadaheadkb\nUse this many KiB of memory to pre-fetch metadata in\nthe hopes of reducing e2fsck runtime. By default,\nthis is set to the size of two block groups' inode\ntables (typically 4MiB on a regular ext4 file sys-\ntem); if this amount is more than 1/50th of total\nphysical memory, readahead is disabled. Set this to\nzero to disable readahead entirely.\n\nbmap2extent\nConvert block-mapped files to extent-mapped files.\n\nfixesonly\nOnly fix damaged metadata; do not optimize htree di-\nrectories or compress extent trees. This option is\nincompatible with the -D and -E bmap2extent options.\n\ncheckencoding\nForce verification of encoded filenames in case-in-\nsensitive directories. This is the default mode if\nthe file system has the strict flag enabled.\n\nunshareblocks\nIf the file system has shared blocks, with the\nshared blocks read-only feature enabled, then this\nwill unshare all shared blocks and unset the read-\nonly feature bit. If there is not enough free space\nthen the operation will fail. If the file system\ndoes not have the read-only feature bit, but has\nshared blocks anyway, then this option will have no\neffect. Note when using this option, if there is no\nfree space to clone blocks, there is no prompt to\ndelete files and instead the operation will fail.\n\nNote that unshareblocks implies the \"-f\" option to\nensure that all passes are run. Additionally, if\n\"-n\" is also specified, e2fsck will simulate trying\nto allocate enough space to deduplicate. If this\nfails, the exit code will be non-zero.\n\n-f Force checking even if the file system seems clean.\n\n-F Flush the file system device's buffer caches before beginning.\nOnly really useful for doing e2fsck time trials.\n\n-j external-journal\nSet the pathname where the external-journal for this file system\ncan be found.\n\n-k When combined with the -c option, any existing bad blocks in the\nbad blocks list are preserved, and any new bad blocks found by\nrunning badblocks(8) will be added to the existing bad blocks\nlist.\n\n-l filename\nAdd the block numbers listed in the file specified by filename\nto the list of bad blocks. The format of this file is the same\nas the one generated by the badblocks(8) program. Note that the\nblock numbers are based on the blocksize of the file system.\nHence, badblocks(8) must be given the blocksize of the file sys-\ntem in order to obtain correct results. As a result, it is much\nsimpler and safer to use the -c option to e2fsck, since it will\nassure that the correct parameters are passed to the badblocks\nprogram.\n\n-L filename\nSet the bad blocks list to be the list of blocks specified by\nfilename. (This option is the same as the -l option, except the\nbad blocks list is cleared before the blocks listed in the file\nare added to the bad blocks list.)\n\n-n Open the file system read-only, and assume an answer of `no' to\nall questions. Allows e2fsck to be used non-interactively.\nThis option may not be specified at the same time as the -p or\n-y options.\n\n-p Automatically repair (\"preen\") the file system. This option\nwill cause e2fsck to automatically fix any file system problems\nthat can be safely fixed without human intervention. If e2fsck\ndiscovers a problem which may require the system administrator\nto take additional corrective action, e2fsck will print a de-\nscription of the problem and then exit with the value 4 logi-\ncally or'ed into the exit code. (See the EXIT CODE section.)\nThis option is normally used by the system's boot scripts. It\nmay not be specified at the same time as the -n or -y options.\n\n-r This option does nothing at all; it is provided only for back-\nwards compatibility.\n\n-t Print timing statistics for e2fsck. If this option is used\ntwice, additional timing statistics are printed on a pass by\npass basis.\n\n-v Verbose mode.\n\n-V Print version information and exit.\n\n-y Assume an answer of `yes' to all questions; allows e2fsck to be\nused non-interactively. This option may not be specified at the\nsame time as the -n or -p options.\n\n-z undofile\nBefore overwriting a file system block, write the old contents\nof the block to an undo file. This undo file can be used with\ne2undo(8) to restore the old contents of the file system should\nsomething go wrong. If the empty string is passed as the\nundofile argument, the undo file will be written to a file\nnamed e2fsck-device.e2undo in the directory specified via the\nE2FSPROGSUNDODIR environment variable.\n\nWARNING: The undo file cannot be used to recover from a power or\nsystem crash.\n", "subsections": [] }, "EXIT CODE": { "content": "The exit code returned by e2fsck is the sum of the following condi-\ntions:\n0 - No errors\n1 - File system errors corrected\n2 - File system errors corrected, system should\nbe rebooted\n4 - File system errors left uncorrected\n8 - Operational error\n16 - Usage or syntax error\n32 - E2fsck canceled by user request\n128 - Shared library error\n", "subsections": [] }, "SIGNALS": { "content": "The following signals have the following effect when sent to e2fsck.\n\nSIGUSR1\nThis signal causes e2fsck to start displaying a completion bar\nor emitting progress information. (See discussion of the -C op-\ntion.)\n\nSIGUSR2\nThis signal causes e2fsck to stop displaying a completion bar or\nemitting progress information.\n", "subsections": [] }, "REPORTING BUGS": { "content": "Almost any piece of software will have bugs. If you manage to find a\nfile system which causes e2fsck to crash, or which e2fsck is unable to\nrepair, please report it to the author.\n\nPlease include as much information as possible in your bug report.\nIdeally, include a complete transcript of the e2fsck run, so I can see\nexactly what error messages are displayed. (Make sure the messages\nprinted by e2fsck are in English; if your system has been configured so\nthat e2fsck's messages have been translated into another language,\nplease set the the LCALL environment variable to C so that the tran-\nscript of e2fsck's output will be useful to me.) If you have a\nwritable file system where the transcript can be stored, the script(1)\nprogram is a handy way to save the output of e2fsck to a file.\n\nIt is also useful to send the output of dumpe2fs(8). If a specific in-\node or inodes seems to be giving e2fsck trouble, try running the de-\nbugfs(8) command and send the output of the stat(1u) command run on the\nrelevant inode(s). If the inode is a directory, the debugfs dump com-\nmand will allow you to extract the contents of the directory inode,\nwhich can sent to me after being first run through uuencode(1). The\nmost useful data you can send to help reproduce the bug is a compressed\nraw image dump of the file system, generated using e2image(8). See the\ne2image(8) man page for more details.\n\nAlways include the full version string which e2fsck displays when it is\nrun, so I know which version you are running.\n", "subsections": [] }, "ENVIRONMENT": { "content": "E2FSCKCONFIG\nDetermines the location of the configuration file (see\ne2fsck.conf(5)).\n", "subsections": [] }, "AUTHOR": { "content": "This version of e2fsck was written by Theodore Ts'o .\n", "subsections": [] }, "SEE ALSO": { "content": "e2fsck.conf(5), badblocks(8), dumpe2fs(8), debugfs(8), e2image(8),\nmke2fs(8), tune2fs(8)\n\nE2fsprogs version 1.46.5 December 2021 E2FSCK(8)", "subsections": [] } } } }