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.
314 .I freei filespec [num]
315 Free the inode specified by
319 is specified, also clear num-1 inodes after the specified inode.
322 Print a list of commands understood by
325 .I htree_dump filespec
326 Dump the hash-indexed directory
328 showing its tree structure.
331 Print a listing of the inodes which use the one or more blocks specified
335 Print the location of the inode data structure (in the inode table)
339 .I init_filesys device blocksize
340 Create an ext2 file system on
344 Note that this does not fully initialize all of the data structures;
347 program. This is just a call to the low-level library, which sets up
348 the superblock and block descriptors.
350 .I kill_file filespec
353 and its blocks. Note that this does not remove any directory
354 entries (if any) to this inode. See the
356 command if you wish to unlink a file.
359 Change the current working directory of the
363 on the native filesystem.
365 .I ln filespec dest_file
370 Note this does not adjust the inode reference counts.
372 .I logdump [-acs] [-b<block>] [-i<filespec>] [-f<journal_file>] [output_file]
373 Dump the contents of the ext3 journal. By default, the journal inode as
374 specified in the superblock. However, this can be overridden with the
376 option, which uses an inode specifier to specify the journal to be
377 used. A file containing journal data can be specified using the
381 option utilizes the backup information in the superblock to locate the
388 program to print the contents of all of the descriptor blocks.
393 to print all journal records that are refer to the specified block.
396 option will print out the contents of all of the data blocks selected by
403 .I ls [-l] [-d] [-p] filespec
404 Print a listing of the files in the directory
408 flag will list files using a more verbose format.
411 flag will list deleted entries in the directory.
414 flag will list the files in a format which is more easily parsable by
415 scripts, as well as making it more clear when there are spaces or other
416 non-printing characters at the end of filenames.
418 .I modify_inode filespec
419 Modify the contents of the inode structure in the inode
425 .I mknod filespec [p|[[c|b] major minor]]
426 Create a special device file (a named pipe, character or block device).
427 If a character or block device is to be made, the
431 device numbers must be specified.
433 .I ncheck [-c] inode_num ...
434 Take the requested list of inode numbers, and print a listing of pathnames
437 flag will enable checking the file type information in the directory
438 entry to make sure it matches the inode's type.
440 .I open [-w] [-e] [-f] [-i] [-c] [-D] [-b blocksize] [-s superblock] device
441 Open a filesystem for editing. The
443 flag forces the filesystem to be opened even if there are some unknown
444 or incompatible filesystem features which would normally
445 prevent the filesystem from being opened. The
447 flag causes the filesystem to be opened in exclusive mode. The
448 .IR -b ", " -c ", " -i ", " -s ", " -w ", and " -D
449 options behave the same as the command-line options to
452 .I punch filespec start_blk [end_blk]
453 Delete the blocks in the inode ranging from
459 is omitted then this command will function as a truncate command; that
460 is, all of the blocks starting at
462 through to the end of the file will be deallocated.
465 Print the current working directory.
471 .I rdump directory destination
474 and all its contents (including regular files, symbolic links, and other
475 directories) into the named
477 which should be an existing directory on the native filesystem.
482 If this causes the inode pointed to by
484 to have no other references, deallocate the file. This command functions
485 as the unlink() system call.
492 .I setb block [count]
493 Mark the block number
496 If the optional argument
500 blocks starting at block number
502 will be marked as allocated.
504 .I set_block_group bgnum field value
505 Modify the block group descriptor specified by
507 so that the block group descriptor field
512 .I seti filespec [num]
515 as in use in the inode bitmap. If
517 is specified, also set num-1 inodes after the specified inode.
519 .I set_inode_field filespec field value
520 Modify the inode specified by
522 so that the inode field
526 The list of valid inode fields which can be set via this command
527 can be displayed by using the command:
528 .B set_inode_field -l
530 .I set_mmp_value field value
531 Modify the multiple-mount protection (mmp) data so that the
536 The list of valid mmp fields which can be set via this command
537 can be displayed by using the command:
540 .I set_super_value field value
541 Set the superblock field
545 The list of valid superblock fields which can be set via this command
546 can be displayed by using the command:
547 .B set_super_value -l
549 .I show_super_stats [-h]
550 List the contents of the super block and the block group descriptors. If the
552 flag is given, only print out the superblock contents.
555 Display the contents of the inode structure of the inode
558 .I testb block [count]
559 Test if the block number
561 is marked as allocated in the block bitmap.
562 If the optional argument
566 blocks starting at block number
573 is marked as allocated in the inode bitmap.
575 .I undel <inode num> [pathname]
576 Undelete the specified inode number (which must be surrounded by angle
577 brackets) so that it and its blocks are marked in use, and optionally
578 link the recovered inode to the specified pathname. The
580 command should always be run after using the
582 command to recover deleted files.
584 Note that if you are recovering a large number of deleted files, linking
585 the inode to a directory may require the directory to be expanded, which
586 could allocate a block that had been used by one of the
587 yet-to-be-undeleted files. So it is safer to undelete all of the
588 inodes without specifying a destination pathname, and then in a separate
589 pass, use the debugfs
591 command to link the inode to the destination pathname, or use
593 to check the filesystem and link all of the recovered inodes to the
594 lost+found directory.
597 Remove the link specified by
599 to an inode. Note this does not adjust the inode reference counts.
601 .I write source_file out_file
602 Create a file in the filesystem named
604 and copy the contents of
606 into the destination file.
607 .SH ENVIRONMENT VARIABLES
609 .B DEBUGFS_PAGER, PAGER
612 program always pipes the output of the some commands through a
613 pager program. These commands include:
614 .IR show_super_stats ,
616 .IR show_inode_info ,
617 .IR list_deleted_inodes ,
620 The specific pager can explicitly specified by the
622 environment variable, and if it is not set, by the
624 environment variable.
626 Note that since a pager is always used, the
628 pager is not particularly appropriate, since it clears the screen before
629 displaying the output of the command and clears the output the screen
630 when the pager is exited. Many users prefer to use the
632 pager for most purposes, which is why the
634 environment variable is available to override the more general
636 environment variable.
639 was written by Theodore Ts'o <tytso@mit.edu>.