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 Specifies that the file system should be opened in catastrophic mode, in
53 which the inode and group bitmaps are not read initially. This can be
54 useful for filesystems with significant corruption, but because of this,
55 catastrophic mode forces the filesystem to be opened read-only.
60 represents an ext2 image file created by the
62 program. Since the ext2 image file only contains the superblock, block
63 group descriptor, block and inode allocation bitmaps, and
66 commands will not function properly.
68 no safety checks are in place, and
70 may fail in interesting ways if commands such as
72 etc. are tried without specifying the
78 is a debugging tool. It has rough edges!
80 .I -d data_source_device
83 option, specifies that
85 should be used when reading blocks not found in the ext2 image file.
86 This includes data, directory, and indirect blocks.
89 Forces the use of the given block size for the file system, rather than
90 detecting the correct block size as normal.
93 Causes the file system superblock to be read from the given block
94 number, instead of using the primary superblock (located at an offset of
95 1024 bytes from the beginning of the filesystem). If you specify the
97 option, you must also provide the blocksize of the filesystem via the
104 to read in commands from
106 and execute them. When
108 is finished executing those commands, it will exit.
113 to open the device using Direct I/O, bypassing the buffer cache. Note
114 that some Linux devices, notably device mapper as of this writing, do
115 not support Direct I/O.
120 to execute the single command
125 print the version number of
133 as an argument to specify an inode (as opposed to a pathname)
134 in the filesystem which is currently opened by
138 argument may be specified in two forms. The first form is an inode
139 number surrounded by angle brackets, e.g.,
141 The second form is a pathname; if the pathname is prefixed by a forward slash
142 ('/'), then it is interpreted relative to the root of the filesystem
143 which is currently opened by
145 If not, the pathname is
146 interpreted relative to the current working directory as maintained by
148 This may be modified by using the
156 This is a list of the commands which
161 Print the blocks used by the inode
165 .I bmap filespec logical_block
166 Print the physical block number corresponding to the logical block number
172 Dump the contents of the inode
177 Change the current working directory to
181 Change the root directory to be the directory
185 Close the currently open file system. If the
187 option is specified, write out any changes to the superblock and block
188 group descriptors to all of the backup superblocks, not just to the
192 Clear the contents of the inode
195 .I dirsearch filespec filename
201 .I dump [-p] filespec out_file
202 Dump the contents of the inode
208 option is given set the owner, group and permissions information on
214 Display the multiple-mount protection (mmp) field values.
216 .I dx_hash [-h hash_alg] [-s hash_seed] filename
217 Calculate the directory hash of
219 The hash algorithm specified with
221 may be "legacy" "half_md4" or "tea".
222 The hash seed specified with
224 must be in UUID format.
226 .I dump_extents [-n] [-l] filespec
227 Dump the the extent tree of the inode
233 to only display the interior nodes in the extent tree. The
237 to only display the leaf nodes in the extent tree.
239 (Please note that the length and range of blocks for the last extent in
240 an interior node is an estimate by the extents library functions, and is
241 not stored in filesystem data structures. Hence, the values displayed
242 may not necessarily by accurate and does not indicate a problem or
243 corruption in the file system.)
245 .I expand_dir filespec
249 .I feature [fs_feature] [-fs_feature] ...
250 Set or clear various filesystem features in the superblock. After setting
251 or clearing any filesystem features that were requested, print the current
252 state of the filesystem feature set.
254 .I filefrag [-dvr] filespec
255 Print the number of contiguous extents in
259 is a directory and the
261 option is not specified,
263 will print the number of contiguous extents for each file in
268 print a tabular listing of the contiguous extents in the
273 to do a recursive listing of the directory.
275 .I find_free_block [count [goal]]
278 free blocks, starting from
282 .I find_free_inode [dir [mode]]
283 Find a free inode and allocate it. If present,
285 specifies the inode number of the directory
286 which the inode is to be located. The second
289 specifies the permissions of the new inode. (If the directory bit is set
290 on the mode, the allocation routine will function differently.)
292 .I freeb block [count]
293 Mark the block number
296 If the optional argument
300 blocks starting at block number
302 will be marked as not allocated.
304 .I freefrag [-c chunk_kb ]
305 Report free space fragmentation on the currently open file system.
308 option is specified then the filefrag command will print how many free
311 can be found in the file system. The chunk size must be a power of two
312 and be larger than the file system block size.
315 Free the inode specified by
319 Print a list of commands understood by
322 .I htree_dump filespec
323 Dump the hash-indexed directory
325 showing its tree structure.
328 Print a listing of the inodes which use the one or more blocks specified
332 Print the location of the inode data structure (in the inode table)
336 .I init_filesys device blocksize
337 Create an ext2 file system on
341 Note that this does not fully initialize all of the data structures;
344 program. This is just a call to the low-level library, which sets up
345 the superblock and block descriptors.
347 .I kill_file filespec
350 and its blocks. Note that this does not remove any directory
351 entries (if any) to this inode. See the
353 command if you wish to unlink a file.
356 Change the current working directory of the
360 on the native filesystem.
362 .I ln filespec dest_file
367 Note this does not adjust the inode reference counts.
369 .I logdump [-acs] [-b<block>] [-i<filespec>] [-f<journal_file>] [output_file]
370 Dump the contents of the ext3 journal. By default, the journal inode as
371 specified in the superblock. However, this can be overridden with the
373 option, which uses an inode specifier to specify the journal to be
374 used. A file containing journal data can be specified using the
378 option utilizes the backup information in the superblock to locate the
385 program to print the contents of all of the descriptor blocks.
390 to print all journal records that are refer to the specified block.
393 option will print out the contents of all of the data blocks selected by
400 .I ls [-l] [-d] [-p] filespec
401 Print a listing of the files in the directory
405 flag will list files using a more verbose format.
408 flag will list deleted entries in the directory.
411 flag will list the files in a format which is more easily parsable by
412 scripts, as well as making it more clear when there are spaces or other
413 non-printing characters at the end of filenames.
415 .I modify_inode filespec
416 Modify the contents of the inode structure in the inode
422 .I mknod filespec [p|[[c|b] major minor]]
423 Create a special device file (a named pipe, character or block device).
424 If a character or block device is to be made, the
428 device numbers must be specified.
430 .I ncheck inode_num ...
431 Take the requested list of inode numbers, and print a listing of pathnames
434 .I open [-w] [-e] [-f] [-i] [-c] [-D] [-b blocksize] [-s superblock] device
435 Open a filesystem for editing. The
437 flag forces the filesystem to be opened even if there are some unknown
438 or incompatible filesystem features which would normally
439 prevent the filesystem from being opened. The
441 flag causes the filesystem to be opened in exclusive mode. The
442 .IR -b ", " -c ", " -i ", " -s ", " -w ", and " -D
443 options behave the same as the command-line options to
446 .I punch filespec start_blk [end_blk]
447 Delete the blocks in the inode ranging from
453 is omitted then this command will function as a truncate command; that
454 is, all of the blocks starting at
456 through to the end of the file will be deallocated.
459 Print the current working directory.
465 .I rdump directory destination
468 and all its contents (including regular files, symbolic links, and other
469 directories) into the named
471 which should be an existing directory on the native filesystem.
476 If this causes the inode pointed to by
478 to have no other references, deallocate the file. This command functions
479 as the unlink() system call.
486 .I setb block [count]
487 Mark the block number
490 If the optional argument
494 blocks starting at block number
496 will be marked as allocated.
498 .I set_block_group bgnum field value
499 Modify the block group descriptor specified by
501 so that the block group descriptor field
509 as in use in the inode bitmap.
511 .I set_inode_field filespec field value
512 Modify the inode specified by
514 so that the inode field
518 The list of valid inode fields which can be set via this command
519 can be displayed by using the command:
520 .B set_inode_field -l
522 .I set_mmp_value field value
523 Modify the multiple-mount protection (mmp) data so that the
528 The list of valid mmp fields which can be set via this command
529 can be displayed by using the command:
532 .I set_super_value field value
533 Set the superblock field
537 The list of valid superblock fields which can be set via this command
538 can be displayed by using the command:
539 .B set_super_value -l
541 .I show_super_stats [-h]
542 List the contents of the super block and the block group descriptors. If the
544 flag is given, only print out the superblock contents.
547 Display the contents of the inode structure of the inode
550 .I testb block [count]
551 Test if the block number
553 is marked as allocated in the block bitmap.
554 If the optional argument
558 blocks starting at block number
565 is marked as allocated in the inode bitmap.
567 .I undel <inode num> [pathname]
568 Undelete the specified inode number (which must be surrounded by angle
569 brackets) so that it and its blocks are marked in use, and optionally
570 link the recovered inode to the specified pathname. The
572 command should always be run after using the
574 command to recover deleted files.
576 Note that if you are recovering a large number of deleted files, linking
577 the inode to a directory may require the directory to be expanded, which
578 could allocate a block that had been used by one of the
579 yet-to-be-undeleted files. So it is safer to undelete all of the
580 inodes without specifying a destination pathname, and then in a separate
581 pass, use the debugfs
583 command to link the inode to the destination pathname, or use
585 to check the filesystem and link all of the recovered inodes to the
586 lost+found directory.
589 Remove the link specified by
591 to an inode. Note this does not adjust the inode reference counts.
593 .I write source_file out_file
594 Create a file in the filesystem named
596 and copy the contents of
598 into the destination file.
599 .SH ENVIRONMENT VARIABLES
601 .B DEBUGFS_PAGER, PAGER
604 program always pipes the output of the some commands through a
605 pager program. These commands include:
606 .IR show_super_stats ,
608 .IR show_inode_info ,
609 .IR list_deleted_inodes ,
612 The specific pager can explicitly specified by the
614 environment variable, and if it is not set, by the
616 environment variable.
618 Note that since a pager is always used, the
620 pager is not particularly appropriate, since it clears the screen before
621 displaying the output of the command and clears the output the screen
622 when the pager is exited. Many users prefer to use the
624 pager for most purposes, which is why the
626 environment variable is available to override the more general
628 environment variable.
631 was written by Theodore Ts'o <tytso@mit.edu>.