2 .\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
3 .\" This file may be copied under the terms of the GNU Public License.
5 .TH DEBUGFS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
7 debugfs \- ext2/ext3/ext4 file system debugger
43 program is an interactive file system debugger. It can be used to
44 examine and change the state of an ext2, ext3, or ext4 file system.
47 is a block device (e.g., /dev/sdXX) or a file containing the file system.
51 Specifies that the file system should be opened in read-write mode.
52 Without this option, the file system is opened in read-only mode.
55 Disables metadata checksum verification. This should only be used if
56 you believe the metadata to be correct despite the complaints of
60 Specifies that the file system should be opened in catastrophic mode, in
61 which the inode and group bitmaps are not read initially. This can be
62 useful for filesystems with significant corruption, but because of this,
63 catastrophic mode forces the filesystem to be opened read-only.
68 represents an ext2 image file created by the
70 program. Since the ext2 image file only contains the superblock, block
71 group descriptor, block and inode allocation bitmaps, and
74 commands will not function properly.
76 no safety checks are in place, and
78 may fail in interesting ways if commands such as
80 etc. are tried without specifying the
86 is a debugging tool. It has rough edges!
88 .I -d data_source_device
91 option, specifies that
93 should be used when reading blocks not found in the ext2 image file.
94 This includes data, directory, and indirect blocks.
97 Forces the use of the given block size (in bytes) for the file system,
98 rather than detecting the correct block size automatically. (This
99 option is rarely needed; it is used primarily when the file system is
100 extremely badly damaged/corrupted.)
103 Causes the file system superblock to be read from the given block
104 number, instead of using the primary superblock (located at an offset of
105 1024 bytes from the beginning of the filesystem). If you specify the
107 option, you must also provide the blocksize of the filesystem via the
110 option is rarely needed; it is used primarily when the file system is
111 extremely badly damaged/corrupted.)
116 to read in commands from
118 and execute them. When
120 is finished executing those commands, it will exit.
125 to open the device using Direct I/O, bypassing the buffer cache. Note
126 that some Linux devices, notably device mapper as of this writing, do
127 not support Direct I/O.
132 to execute the single command
137 print the version number of
142 Before overwriting a file system block, write the old contents of the block to
143 an undo file. This undo file can be used with e2undo(8) to restore the old
144 contents of the file system should something go wrong. If the empty string is
145 passed as the undo_file argument, the undo file will be written to a file named
146 resize2fs-\fIdevice\fR.e2undo in the directory specified via the
147 \fIE2FSPROGS_UNDO_DIR\fR environment variable.
149 WARNING: The undo file cannot be used to recover from a power or system crash.
155 as an argument to specify an inode (as opposed to a pathname)
156 in the filesystem which is currently opened by
160 argument may be specified in two forms. The first form is an inode
161 number surrounded by angle brackets, e.g.,
163 The second form is a pathname; if the pathname is prefixed by a forward slash
164 ('/'), then it is interpreted relative to the root of the filesystem
165 which is currently opened by
167 If not, the pathname is
168 interpreted relative to the current working directory as maintained by
170 This may be modified by using the
178 This is a list of the commands which
182 .BI blocks " filespec"
183 Print the blocks used by the inode
187 .BI bmap " [ -a ] filespec logical_block [physical_block]"
188 Print or set the physical block number corresponding to the logical block number
194 flag is specified, try to allocate a block if necessary.
196 .BI block_dump " [-f filespec] block_num"
197 Dump the filesystem block given by
199 in hex and ASCII format to the console. If the
201 option is specified, the block number is relative to the start of the given
205 Dump the contents of the inode
210 Change the current working directory to
213 .BI chroot " filespec"
214 Change the root directory to be the directory
218 Close the currently open file system. If the
220 option is specified, write out any changes to the superblock and block
221 group descriptors to all of the backup superblocks, not just to the
225 Clear the contents of the inode
228 .BI copy_inode " source_inode destination_inode"
229 Copy the conents of the inode structure in
231 and use it to overwrite the inode structure at
232 .IR destination_inode .
234 .BI dirsearch " filespec filename"
241 Mark the filesystem as dirty, so that the superblocks will be written on exit.
243 .BI dump " [-p] filespec out_file"
244 Dump the contents of the inode
250 option is given set the owner, group and permissions information on
255 .BI dump_mmp " [mmp_block]"
256 Display the multiple-mount protection (mmp) field values. If
258 is specified then verify and dump the MMP values from the given block
259 number, otherwise use the
261 field in the superblock to locate and use the existing MMP block.
263 .BI dx_hash " [-h hash_alg] [-s hash_seed] filename"
264 Calculate the directory hash of
266 The hash algorithm specified with
269 .BR legacy , " half_md4" ", or " tea .
270 The hash seed specified with
272 must be in UUID format.
274 .BI dump_extents " [-n] [-l] filespec"
275 Dump the the extent tree of the inode
281 to only display the interior nodes in the extent tree. The
285 to only display the leaf nodes in the extent tree.
287 (Please note that the length and range of blocks for the last extent in
288 an interior node is an estimate by the extents library functions, and is
289 not stored in filesystem data structures. Hence, the values displayed
290 may not necessarily by accurate and does not indicate a problem or
291 corruption in the file system.)
293 .BI ea_get " [-f outfile] filespec attr_name"
294 Retrieve the value of the extended attribute
298 and write it either to stdout or to \fIoutfile\fR.
300 .BI ea_list " filespec
301 List the extended attributes associated with the file
305 .BI ea_set " [-f infile] filespec attr_name attr_value
306 Set the value of the extended attribute
312 or read it from \fIinfile\fR.
314 .BI ea_rm " filespec attr_names...
315 Remove the extended attribute
317 from the file \fIfilespec\fR.
319 .BI expand_dir " filespec"
323 .BI fallocate " filespec start_block [end_block]
324 Allocate and map uninitialized blocks into \fIfilespec\fR between
325 logical block \fIstart_block\fR and \fIend_block\fR, inclusive. If
326 \fIend_block\fR is not supplied, this function maps until it runs out
327 of free disk blocks or the maximum file size is reached. Existing
328 mappings are left alone.
330 .BI feature " [fs_feature] [-fs_feature] ..."
331 Set or clear various filesystem features in the superblock. After setting
332 or clearing any filesystem features that were requested, print the current
333 state of the filesystem feature set.
335 .BI filefrag " [-dvr] filespec"
336 Print the number of contiguous extents in
340 is a directory and the
342 option is not specified,
344 will print the number of contiguous extents for each file in
349 print a tabular listing of the contiguous extents in the
354 to do a recursive listing of the directory.
356 .BI find_free_block " [count [goal]]"
359 free blocks, starting from
361 and allocate it. Also available as
364 .BI find_free_inode " [dir [mode]]"
365 Find a free inode and allocate it. If present,
367 specifies the inode number of the directory
368 which the inode is to be located. The second
371 specifies the permissions of the new inode. (If the directory bit is set
372 on the mode, the allocation routine will function differently.) Also
376 .BI freeb " block [count]"
377 Mark the block number
380 If the optional argument
384 blocks starting at block number
386 will be marked as not allocated.
388 .BI freefrag " [-c chunk_kb]"
389 Report free space fragmentation on the currently open file system.
392 option is specified then the filefrag command will print how many free
395 can be found in the file system. The chunk size must be a power of two
396 and be larger than the file system block size.
398 .BI freei " filespec [num]"
399 Free the inode specified by
403 is specified, also clear num-1 inodes after the specified inode.
406 Print a list of commands understood by
409 .BI htree_dump " filespec"
410 Dump the hash-indexed directory
412 showing its tree structure.
414 .BI icheck " block ..."
415 Print a listing of the inodes which use the one or more blocks specified
418 .BI inode_dump " filespec"
419 Print the contents of the inode data structure in hex and ASCII format.
422 Print the location of the inode data structure (in the inode table)
426 .BI init_filesys " device blocksize"
427 Create an ext2 file system on
431 Note that this does not fully initialize all of the data structures;
434 program. This is just a call to the low-level library, which sets up
435 the superblock and block descriptors.
438 Close the open journal.
440 .BI journal_open " [-c] [-v ver] [-j ext_jnl]
441 Opens the journal for reading and writing. Journal checksumming can
442 be enabled by supplying \fI-c\fR; checksum formats 2 and 3 can be
443 selected with the \fI-v\fR option. An external journal can be loaded
447 Replay all transactions in the open journal.
449 .BI journal_write " [-b blocks] [-r revoke] [-c] file
450 Write a transaction to the open journal. The list of blocks to write
451 should be supplied as a comma-separated list in \fIblocks\fR; the
452 blocks themselves should be readable from \fIfile\fR. A list of
453 blocks to revoke can be supplied as a comma-separated list in
454 \fIrevoke\fR. By default, a commit record is written at the end; the
455 \fI-c\fR switch writes an uncommitted transaction.
457 .BI kill_file " filespec"
460 and its blocks. Note that this does not remove any directory
461 entries (if any) to this inode. See the
463 command if you wish to unlink a file.
466 Change the current working directory of the
470 on the native filesystem.
472 .BI ln " filespec dest_file"
475 which is a hard link to
477 Note this does not adjust the inode reference counts.
479 .BI logdump " [-acsO] [-b block] [-i filespec] [-f journal_file] [output_file]"
480 Dump the contents of the ext3 journal. By default, dump the journal inode as
481 specified in the superblock. However, this can be overridden with the
483 option, which dumps the journal from the internal inode given by
485 A regular file containing journal data can be specified using the
489 option utilizes the backup information in the superblock to locate the
496 program to print the contents of all of the descriptor blocks.
501 to print all journal records that are refer to the specified block.
504 option will print out the contents of all of the data blocks selected by
513 option causes logdump to display old (checkpointed) journal entries.
514 This can be used to try to track down journal problems even after the
515 journal has been replayed.
517 .BI ls " [-l] [-c] [-d] [-p] [-r] filespec"
518 Print a listing of the files in the directory
522 flag causes directory block checksums (if present) to be displayed.
525 flag will list deleted entries in the directory.
528 flag will list files using a more verbose format.
531 flag will list the files in a format which is more easily parsable by
532 scripts, as well as making it more clear when there are spaces or other
533 non-printing characters at the end of filenames.
536 flag will force the printing of the filename, even if it is encrypted.
538 .BI list_deleted_inodes " [limit]"
539 List deleted inodes, optionally limited to those deleted within
541 seconds ago. Also available as
544 This command was useful for recovering from accidental file deletions
545 for ext2 file systems. Unfortunately, it is not useful for this purpose
546 if the files were deleted using ext3 or ext4, since the inode's
547 data blocks are no longer available after the inode is released.
549 .BI modify_inode " filespec"
550 Modify the contents of the inode structure in the inode
555 .BI mkdir " filespec"
558 .BI mknod " filespec [p|[[c|b] major minor]]"
559 Create a special device file (a named pipe, character or block device).
560 If a character or block device is to be made, the
564 device numbers must be specified.
566 .BI ncheck " [-c] inode_num ..."
567 Take the requested list of inode numbers, and print a listing of pathnames
570 flag will enable checking the file type information in the directory
571 entry to make sure it matches the inode's type.
573 .BI open " [-weficD] [-b blocksize] [-s superblock] [-z undo_file] device"
574 Open a filesystem for editing. The
576 flag forces the filesystem to be opened even if there are some unknown
577 or incompatible filesystem features which would normally
578 prevent the filesystem from being opened. The
580 flag causes the filesystem to be opened in exclusive mode. The
581 .IR -b ", " -c ", " -i ", " -s ", " -w ", and " -D
582 options behave the same as the command-line options to
585 .BI punch " filespec start_blk [end_blk]"
586 Delete the blocks in the inode ranging from
592 is omitted then this command will function as a truncate command; that
593 is, all of the blocks starting at
595 through to the end of the file will be deallocated.
597 .BI symlink " filespec target"
598 Make a symbolic link.
601 Print the current working directory.
607 .BI rdump " directory[...] destination"
612 and all its contents (including regular files, symbolic links, and other
613 directories) into the named
615 which should be an existing directory on the native filesystem.
620 If this causes the inode pointed to by
622 to have no other references, deallocate the file. This command functions
623 as the unlink() system call.
626 .BI rmdir " filespec"
630 .BI setb " block [count]"
631 Mark the block number
634 If the optional argument
638 blocks starting at block number
640 will be marked as allocated.
642 .BI set_block_group " bgnum field value"
643 Modify the block group descriptor specified by
645 so that the block group descriptor field
652 .BI seti " filespec [num]"
655 as in use in the inode bitmap. If
657 is specified, also set num-1 inodes after the specified inode.
659 .BI set_inode_field " filespec field value"
660 Modify the inode specified by
662 so that the inode field
666 The list of valid inode fields which can be set via this command
667 can be displayed by using the command:
668 .B set_inode_field -l
672 .BI set_mmp_value " field value"
673 Modify the multiple-mount protection (MMP) data so that the MMP field
677 The list of valid MMP fields which can be set via this command
678 can be displayed by using the command:
683 .BI set_super_value " field value"
684 Set the superblock field
688 The list of valid superblock fields which can be set via this command
689 can be displayed by using the command:
690 .B set_super_value -l
694 .BI show_super_stats " [-h]"
695 List the contents of the super block and the block group descriptors. If the
697 flag is given, only print out the superblock contents. Also available as
701 Display the contents of the inode structure of the inode
704 .BI testb " block [count]"
705 Test if the block number
707 is marked as allocated in the block bitmap.
708 If the optional argument
712 blocks starting at block number
716 .BI testi " filespec"
719 is marked as allocated in the inode bitmap.
721 .BI undel " <inode_number> [pathname]"
722 Undelete the specified inode number (which must be surrounded by angle
723 brackets) so that it and its blocks are marked in use, and optionally
724 link the recovered inode to the specified pathname. The
726 command should always be run after using the
728 command to recover deleted files.
730 Note that if you are recovering a large number of deleted files, linking
731 the inode to a directory may require the directory to be expanded, which
732 could allocate a block that had been used by one of the
733 yet-to-be-undeleted files. So it is safer to undelete all of the
734 inodes without specifying a destination pathname, and then in a separate
735 pass, use the debugfs
737 command to link the inode to the destination pathname, or use
739 to check the filesystem and link all of the recovered inodes to the
740 lost+found directory.
742 .BI unlink " pathname"
743 Remove the link specified by
745 to an inode. Note this does not adjust the inode reference counts.
747 .BI write " source_file out_file"
750 into a newly-created file in the filesystem named
753 .BI zap_block " [-f filespec] [-o offset] [-l length] [-p pattern] block_num"
754 Overwrite the block specified by
756 with zero (NUL) bytes, or if
758 is given use the byte specified by
764 is relative to the start of the file given by
770 options limit the range of bytes to zap to the specified
774 relative to the start of the block.
776 .BI zap_block " [-f filespec] [-b bit] block_num"
777 Bit-flip portions of the physical
783 is a logical block relative to the start of
785 .SH ENVIRONMENT VARIABLES
787 .B DEBUGFS_PAGER, PAGER
790 program always pipes the output of the some commands through a
791 pager program. These commands include:
792 .IR show_super_stats " (" stats ),
793 .IR list_directory " (" ls ),
794 .IR show_inode_info " (" stat ),
795 .IR list_deleted_inodes " (" lsdel ),
798 The specific pager can explicitly specified by the
800 environment variable, and if it is not set, by the
802 environment variable.
804 Note that since a pager is always used, the
806 pager is not particularly appropriate, since it clears the screen before
807 displaying the output of the command and clears the output the screen
808 when the pager is exited. Many users prefer to use the
810 pager for most purposes, which is why the
812 environment variable is available to override the more general
814 environment variable.
817 was written by Theodore Ts'o <tytso@mit.edu>.