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
160 .I bmap filespec logical_block
161 Print the physical block number corresponding to the logical block number
167 Dump the contents of the inode
172 Change the current working directory to
176 Change the root directory to be the directory
180 Close the currently open file system. If the
182 option is specified, write out any changes to the superblock and block
183 group descriptors to all of the backup superblocks, not just to the
187 Clear the contents of the inode
190 .I dump [-p] filespec out_file
191 Dump the contents of the inode
197 option is given set the owner, group and permissions information on
202 .I dump_extents [-n] [-l] filespec
203 Dump the the extent tree of the inode
209 to only display the interior nodes in the extent tree. The
213 to only display the leaf nodes in the extent tree.
215 (Please note that the length and range of blocks for the last extent in
216 an interior node is an estimate by the extents library functions, and is
217 not stored in filesystem data structures. Hence, the values displayed
218 may not necessarily by accurate and does not indicate a problem or
219 corruption in the file system.)
221 .I expand_dir filespec
225 .I feature [fs_feature] [-fs_feature] ...
226 Set or clear various filesystem features in the superblock. After setting
227 or clearing any filesystem features that were requested, print the current
228 state of the filesystem feature set.
230 .I find_free_block [count [goal]]
233 free blocks, starting from
237 .I find_free_inode [dir [mode]]
238 Find a free inode and allocate it. If present,
240 specifies the inode number of the directory
241 which the inode is to be located. The second
244 specifies the permissions of the new inode. (If the directory bit is set
245 on the mode, the allocation routine will function differently.)
247 .I freeb block [count]
248 Mark the block number
251 If the optional argument
255 blocks starting at block number
257 will be marked as not allocated.
260 Free the inode specified by
264 Print a list of commands understood by
268 Print a listing of the inodes which use the one or more blocks specified
272 Print the location of the inode data structure (in the inode table)
276 .I init_filesys device blocksize
277 Create an ext2 file system on
281 Note that this does not fully initialize all of the data structures;
284 program. This is just a call to the low-level library, which sets up
285 the superblock and block descriptors.
287 .I kill_file filespec
290 and its blocks. Note that this does not remove any directory
291 entries (if any) to this inode. See the
293 command if you wish to unlink a file.
296 Change the current working directory of the
300 on the native filesystem.
302 .I ln filespec dest_file
307 Note this does not adjust the inode reference counts.
309 .I logdump [-acs] [-b<block>] [-i<filespec>] [-f<journal_file>] [output_file]
310 Dump the contents of the ext3 journal. By default, the journal inode as
311 specified in the superblock. However, this can be overridden with the
313 option, which uses an inode specifier to specify the journal to be
314 used. A file containing journal data can be specified using the
318 option utilizes the backup information in the superblock to locate the
325 program to print the contents of all of the descriptor blocks.
330 to print all journal records that are refer to the specified block.
333 option will print out the contents of all of the data blocks selected by
340 .I ls [-l] [-d] [-p] filespec
341 Print a listing of the files in the directory
345 flag will list files using a more verbose format.
348 flag will list deleted entries in the directory.
351 flag will list the files in a format which is more easily parsable by
352 scripts, as well as making it more clear when there are spaces or other
353 non-printing characters at the end of filenames.
355 .I modify_inode filespec
356 Modify the contents of the inode structure in the inode
362 .I mknod filespec [p|[[c|b] major minor]]
363 Create a special device file (a named pipe, character or block device).
364 If a character or block device is to be made, the
368 device numbers must be specified.
370 .I ncheck inode_num ...
371 Take the requested list of inode numbers, and print a listing of pathnames
374 .I open [-w] [-e] [-f] [-i] [-c] [-D] [-b blocksize] [-s superblock] device
375 Open a filesystem for editing. The
377 flag forces the filesystem to be opened even if there are some unknown
378 or incompatible filesystem features which would normally
379 prevent the filesystem from being opened. The
381 flag causes the filesystem to be opened in exclusive mode. The
382 .IR -b ", " -c ", " -i ", " -s ", " -w ", and " -D
383 options behave the same as the command-line options to
386 .I punch filespec start_blk [end_blk]
387 Delete the blocks in the inode ranging from
393 is omitted then this command will function as a truncate command; that
394 is, all of the blocks starting at
396 through to the end of the file will be deallocated.
399 Print the current working directory.
405 .I rdump directory destination
408 and all its contents (including regular files, symbolic links, and other
409 directories) into the named
411 which should be an existing directory on the native filesystem.
416 If this causes the inode pointed to by
418 to have no other references, deallocate the file. This command functions
419 as the unlink() system call.
426 .I setb block [count]
427 Mark the block number
430 If the optional argument
434 blocks starting at block number
436 will be marked as allocated.
438 .I set_block_group bgnum field value
439 Modify the block group descriptor specified by
441 so that the block group descriptor field
449 as in use in the inode bitmap.
451 .I set_inode_field filespec field value
452 Modify the inode specified by
454 so that the inode field
458 The list of valid inode fields which can be set via this command
459 can be displayed by using the command:
460 .B set_inode_field -l
462 .I set_super_value field value
463 Set the superblock field
467 The list of valid superblock fields which can be set via this command
468 can be displayed by using the command:
469 .B set_super_value -l
471 .I show_super_stats [-h]
472 List the contents of the super block and the block group descriptors. If the
474 flag is given, only print out the superblock contents.
477 Display the contents of the inode structure of the inode
480 .I testb block [count]
481 Test if the block number
483 is marked as allocated in the block bitmap.
484 If the optional argument
488 blocks starting at block number
495 is marked as allocated in the inode bitmap.
497 .I undel <inode num> [pathname]
498 Undelete the specified inode number (which must be surrounded by angle
499 brackets) so that it and its blocks are marked in use, and optionally
500 link the recovered inode to the specified pathname. The
502 command should always be run after using the
504 command to recover deleted files.
506 Note that if you are recovering a large number of deleted files, linking
507 the inode to a directory may require the directory to be expanded, which
508 could allocate a block that had been used by one of the
509 yet-to-be-undeleted files. So it is safer to undelete all of the
510 inodes without specifying a destination pathname, and then in a separate
511 pass, use the debugfs
513 command to link the inode to the destination pathname, or use
515 to check the filesystem and link all of the recovered inodes to the
516 lost+found directory.
519 Remove the link specified by
521 to an inode. Note this does not adjust the inode reference counts.
523 .I write source_file out_file
524 Create a file in the filesystem named
526 and copy the contents of
528 into the destination file.
529 .SH ENVIRONMENT VARIABLES
531 .B DEBUGFS_PAGER, PAGER
534 program always pipes the output of the some commands through a
535 pager program. These commands include:
536 .IR show_super_stats ,
538 .IR show_inode_info ,
539 .IR list_deleted_inodes ,
542 The specific pager can explicitly specified by the
544 environment variable, and if it is not set, by the
546 environment variable.
548 Note that since a pager is always used, the
550 pager is not particularly appropriate, since it clears the screen before
551 displaying the output of the command and clears the output the screen
552 when the pager is exited. Many users prefer to use the
554 pager for most purposes, which is why the
556 environment variable is available to override the more general
558 environment variable.
561 was written by Theodore Ts'o <tytso@mit.edu>.