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
39 program is an interactive file system debugger. It can be used to
40 examine and change the state of an ext2, ext3, or ext4 file system.
43 is the special file corresponding to the device containing the
44 file system (e.g /dev/hdXX).
48 Specifies that the file system should be opened in read-write mode.
49 Without this option, the file system is opened in read-only mode.
52 Disables metadata checksum verification. This should only be used if
53 you believe the metadata to be correct despite the complaints of
57 Specifies that the file system should be opened in catastrophic mode, in
58 which the inode and group bitmaps are not read initially. This can be
59 useful for filesystems with significant corruption, but because of this,
60 catastrophic mode forces the filesystem to be opened read-only.
65 represents an ext2 image file created by the
67 program. Since the ext2 image file only contains the superblock, block
68 group descriptor, block and inode allocation bitmaps, and
71 commands will not function properly.
73 no safety checks are in place, and
75 may fail in interesting ways if commands such as
77 etc. are tried without specifying the
83 is a debugging tool. It has rough edges!
85 .I -d data_source_device
88 option, specifies that
90 should be used when reading blocks not found in the ext2 image file.
91 This includes data, directory, and indirect blocks.
94 Forces the use of the given block size for the file system, rather than
95 detecting the correct block size as normal.
98 Causes the file system superblock to be read from the given block
99 number, instead of using the primary superblock (located at an offset of
100 1024 bytes from the beginning of the filesystem). If you specify the
102 option, you must also provide the blocksize of the filesystem via the
109 to read in commands from
111 and execute them. When
113 is finished executing those commands, it will exit.
118 to open the device using Direct I/O, bypassing the buffer cache. Note
119 that some Linux devices, notably device mapper as of this writing, do
120 not support Direct I/O.
125 to execute the single command
130 print the version number of
138 as an argument to specify an inode (as opposed to a pathname)
139 in the filesystem which is currently opened by
143 argument may be specified in two forms. The first form is an inode
144 number surrounded by angle brackets, e.g.,
146 The second form is a pathname; if the pathname is prefixed by a forward slash
147 ('/'), then it is interpreted relative to the root of the filesystem
148 which is currently opened by
150 If not, the pathname is
151 interpreted relative to the current working directory as maintained by
153 This may be modified by using the
161 This is a list of the commands which
166 Print the blocks used by the inode
170 .I bmap filespec logical_block
171 Print the physical block number corresponding to the logical block number
177 Dump the contents of the inode
182 Change the current working directory to
186 Change the root directory to be the directory
190 Close the currently open file system. If the
192 option is specified, write out any changes to the superblock and block
193 group descriptors to all of the backup superblocks, not just to the
197 Clear the contents of the inode
200 .I dirsearch filespec filename
206 .I dump [-p] filespec out_file
207 Dump the contents of the inode
213 option is given set the owner, group and permissions information on
219 Display the multiple-mount protection (mmp) field values.
221 .I dx_hash [-h hash_alg] [-s hash_seed] filename
222 Calculate the directory hash of
224 The hash algorithm specified with
226 may be "legacy" "half_md4" or "tea".
227 The hash seed specified with
229 must be in UUID format.
231 .I dump_extents [-n] [-l] filespec
232 Dump the the extent tree of the inode
238 to only display the interior nodes in the extent tree. The
242 to only display the leaf nodes in the extent tree.
244 (Please note that the length and range of blocks for the last extent in
245 an interior node is an estimate by the extents library functions, and is
246 not stored in filesystem data structures. Hence, the values displayed
247 may not necessarily by accurate and does not indicate a problem or
248 corruption in the file system.)
250 .I expand_dir filespec
254 .I feature [fs_feature] [-fs_feature] ...
255 Set or clear various filesystem features in the superblock. After setting
256 or clearing any filesystem features that were requested, print the current
257 state of the filesystem feature set.
259 .I filefrag [-dvr] filespec
260 Print the number of contiguous extents in
264 is a directory and the
266 option is not specified,
268 will print the number of contiguous extents for each file in
273 print a tabular listing of the contiguous extents in the
278 to do a recursive listing of the directory.
280 .I find_free_block [count [goal]]
283 free blocks, starting from
287 .I find_free_inode [dir [mode]]
288 Find a free inode and allocate it. If present,
290 specifies the inode number of the directory
291 which the inode is to be located. The second
294 specifies the permissions of the new inode. (If the directory bit is set
295 on the mode, the allocation routine will function differently.)
297 .I freeb block [count]
298 Mark the block number
301 If the optional argument
305 blocks starting at block number
307 will be marked as not allocated.
309 .I freefrag [-c chunk_kb ]
310 Report free space fragmentation on the currently open file system.
313 option is specified then the filefrag command will print how many free
316 can be found in the file system. The chunk size must be a power of two
317 and be larger than the file system block size.
319 .I freei filespec [num]
320 Free the inode specified by
324 is specified, also clear num-1 inodes after the specified inode.
327 Print a list of commands understood by
330 .I htree_dump filespec
331 Dump the hash-indexed directory
333 showing its tree structure.
336 Print a listing of the inodes which use the one or more blocks specified
340 Print the location of the inode data structure (in the inode table)
344 .I init_filesys device blocksize
345 Create an ext2 file system on
349 Note that this does not fully initialize all of the data structures;
352 program. This is just a call to the low-level library, which sets up
353 the superblock and block descriptors.
355 .I kill_file filespec
358 and its blocks. Note that this does not remove any directory
359 entries (if any) to this inode. See the
361 command if you wish to unlink a file.
364 Change the current working directory of the
368 on the native filesystem.
370 .I ln filespec dest_file
375 Note this does not adjust the inode reference counts.
377 .I logdump [-acs] [-b<block>] [-i<filespec>] [-f<journal_file>] [output_file]
378 Dump the contents of the ext3 journal. By default, the journal inode as
379 specified in the superblock. However, this can be overridden with the
381 option, which uses an inode specifier to specify the journal to be
382 used. A file containing journal data can be specified using the
386 option utilizes the backup information in the superblock to locate the
393 program to print the contents of all of the descriptor blocks.
398 to print all journal records that are refer to the specified block.
401 option will print out the contents of all of the data blocks selected by
408 .I ls [-l] [-c] [-d] [-p] filespec
409 Print a listing of the files in the directory
413 flag will list files using a more verbose format.
416 flag causes directory block checksums (if present) to be displayed.
419 flag will list deleted entries in the directory.
422 flag will list the files in a format which is more easily parsable by
423 scripts, as well as making it more clear when there are spaces or other
424 non-printing characters at the end of filenames.
426 .I modify_inode filespec
427 Modify the contents of the inode structure in the inode
433 .I mknod filespec [p|[[c|b] major minor]]
434 Create a special device file (a named pipe, character or block device).
435 If a character or block device is to be made, the
439 device numbers must be specified.
441 .I ncheck [-c] inode_num ...
442 Take the requested list of inode numbers, and print a listing of pathnames
445 flag will enable checking the file type information in the directory
446 entry to make sure it matches the inode's type.
448 .I open [-w] [-e] [-f] [-i] [-c] [-D] [-b blocksize] [-s superblock] device
449 Open a filesystem for editing. The
451 flag forces the filesystem to be opened even if there are some unknown
452 or incompatible filesystem features which would normally
453 prevent the filesystem from being opened. The
455 flag causes the filesystem to be opened in exclusive mode. The
456 .IR -b ", " -c ", " -i ", " -s ", " -w ", and " -D
457 options behave the same as the command-line options to
460 .I punch filespec start_blk [end_blk]
461 Delete the blocks in the inode ranging from
467 is omitted then this command will function as a truncate command; that
468 is, all of the blocks starting at
470 through to the end of the file will be deallocated.
473 Print the current working directory.
479 .I rdump directory destination
482 and all its contents (including regular files, symbolic links, and other
483 directories) into the named
485 which should be an existing directory on the native filesystem.
490 If this causes the inode pointed to by
492 to have no other references, deallocate the file. This command functions
493 as the unlink() system call.
500 .I setb block [count]
501 Mark the block number
504 If the optional argument
508 blocks starting at block number
510 will be marked as allocated.
512 .I set_block_group bgnum field value
513 Modify the block group descriptor specified by
515 so that the block group descriptor field
520 .I seti filespec [num]
523 as in use in the inode bitmap. If
525 is specified, also set num-1 inodes after the specified inode.
527 .I set_inode_field filespec field value
528 Modify the inode specified by
530 so that the inode field
534 The list of valid inode fields which can be set via this command
535 can be displayed by using the command:
536 .B set_inode_field -l
538 .I set_mmp_value field value
539 Modify the multiple-mount protection (mmp) data so that the
544 The list of valid mmp fields which can be set via this command
545 can be displayed by using the command:
548 .I set_super_value field value
549 Set the superblock field
553 The list of valid superblock fields which can be set via this command
554 can be displayed by using the command:
555 .B set_super_value -l
557 .I show_super_stats [-h]
558 List the contents of the super block and the block group descriptors. If the
560 flag is given, only print out the superblock contents.
563 Display the contents of the inode structure of the inode
566 .I testb block [count]
567 Test if the block number
569 is marked as allocated in the block bitmap.
570 If the optional argument
574 blocks starting at block number
581 is marked as allocated in the inode bitmap.
583 .I undel <inode num> [pathname]
584 Undelete the specified inode number (which must be surrounded by angle
585 brackets) so that it and its blocks are marked in use, and optionally
586 link the recovered inode to the specified pathname. The
588 command should always be run after using the
590 command to recover deleted files.
592 Note that if you are recovering a large number of deleted files, linking
593 the inode to a directory may require the directory to be expanded, which
594 could allocate a block that had been used by one of the
595 yet-to-be-undeleted files. So it is safer to undelete all of the
596 inodes without specifying a destination pathname, and then in a separate
597 pass, use the debugfs
599 command to link the inode to the destination pathname, or use
601 to check the filesystem and link all of the recovered inodes to the
602 lost+found directory.
605 Remove the link specified by
607 to an inode. Note this does not adjust the inode reference counts.
609 .I write source_file out_file
610 Create a file in the filesystem named
612 and copy the contents of
614 into the destination file.
615 .SH ENVIRONMENT VARIABLES
617 .B DEBUGFS_PAGER, PAGER
620 program always pipes the output of the some commands through a
621 pager program. These commands include:
622 .IR show_super_stats ,
624 .IR show_inode_info ,
625 .IR list_deleted_inodes ,
628 The specific pager can explicitly specified by the
630 environment variable, and if it is not set, by the
632 environment variable.
634 Note that since a pager is always used, the
636 pager is not particularly appropriate, since it clears the screen before
637 displaying the output of the command and clears the output the screen
638 when the pager is exited. Many users prefer to use the
640 pager for most purposes, which is why the
642 environment variable is available to override the more general
644 environment variable.
647 was written by Theodore Ts'o <tytso@mit.edu>.