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 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 file system.
43 is the special file corresponding to the device containing the ext2
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 execute the single command
118 print the version number of
126 as an argument to specify an inode (as opposed to a pathname)
127 in the filesystem which is currently opened by
131 argument may be specified in two forms. The first form is an inode
132 number surrounded by angle brackets, e.g.,
134 The second form is a pathname; if the pathname is prefixed by a forward slash
135 ('/'), then it is interpreted relative to the root of the filesystem
136 which is currently opened by
138 If not, the pathname is
139 interpreted relative to the current working directory as maintained by
141 This may be modified by using the
149 This is a list of the commands which
153 .I bmap filespec logical_block
154 Print the physical block number corresponding to the logical block number
160 Dump the contents of the inode
165 Change the current working directory to
169 Change the root directory to be the directory
173 Close the currently open file system.
176 Clear the contents of the inode
179 .I dump [-p] filspec out_file
180 Dump the contents of the inode
186 option is given set the owner, group and permissions information on
191 .I expand_dir filespec
195 .I feature [fs_feature] [-fs_feature] ...
196 Set or clear various filesystem features in the superblock. After setting
197 or clearing any filesystem features that were requested, print the current
198 state of the filesystem feature set.
200 .I find_free_block [count [goal]]
203 free blocks, starting from
207 .I find_free_inode [dir [mode]]
208 Find a free inode and allocate it. If present,
210 specifies the inode number of the directory
211 which the inode is to be located. The second
214 specifies the permissions of the new inode. (If the directory bit is set
215 on the mode, the allocation routine will function differently.)
217 .I freeb block [count]
218 Mark the block number
221 If the optional argument
225 blocks starting at block number
227 will be marked as not allocated.
230 Free the inode specified by
234 Print a list of commands understood by
238 Print a listing of the inodes which use the one or more blocks specified
242 Print the location of the inode data structure (in the inode table)
246 .I init_filesys device blocksize
247 Create an ext2 file system on
251 Note that this does not fully initialize all of the data structures;
254 program. This is just a call to the low-level library, which sets up
255 the superblock and block descriptors.
257 .I kill_file filespec
260 and its blocks. Note that this does not remove any directory
261 entries (if any) to this inode. See the
263 command if you wish to unlink a file.
266 Change the current working directory of the
270 on the native filesystem.
272 .I ln filespec dest_file
277 Note this does not adjust the inode reference counts.
279 .I logdump [-acs] [-b<block>] [-i<filespec>] [-f<journal_file>] [output_file]
280 Dump the contents of the ext3 journal. By default, the journal inode as
281 specified in the superblock. However, this can be overridden with the
283 option, which uses an inode specifier to specify the journal to be
284 used. A file containing journal data can be specified using the
288 option utilizes the backup information in the superblock to locate the
295 program to print the contents of all of the descriptor blocks.
300 to print all journal records that are refer to the specified block.
303 option will print out the contents of all of the data blocks selected by
310 .I ls [-l] [-d] [-p] filespec
311 Print a listing of the files in the directory
315 flag will list files using a more verbose format.
318 flag will list deleted entries in the directory.
321 flag will list the files in a format which is more easily parsable by
322 scripts, as well as making it more clear when there are spaces or other
323 non-prinitng characters at the end of filenames.
325 .I modify_inode filespec
326 Modify the contents of the inode structure in the inode
332 .I mknod filespec [p|[[c|b] major minor]]
333 Create a special device file (a named pipe, character or block device).
334 If a character or block device is to be made, the
338 device numbers must be specified.
340 .I ncheck inode_num ...
341 Take the requested list of inode numbers, and print a listing of pathnames
344 .I open [-w] [-e] [-f] [-i] [-c] [-b blocksize] [-s superblock] device
345 Open a filesystem for editing. The
347 flag forces the filesystem to be opened even if there are some unknown
348 or incompatible filesystem features which would normally
349 prevent the filesystem from being opened. The
351 flag causes the filesystem to be opened in exclusive mode. The
352 .IR -b ", " -c ", " -i ", " -s ", and " -w
353 options behave the same as the command-line options to
357 Print the current working directory.
363 .I rdump directory destination
366 and all its contents (including regular files, symbolic links, and other
367 directories) into the named
369 which should be an existing directory on the native filesystem.
374 If this causes the inode pointed to by
376 to have no other references, deallocate the file. This command functions
377 as the unlink() system call.
384 .I setb block [count]
385 Mark the block number
388 If the optional argument
392 blocks starting at block number
394 will be marked as allocated.
396 .I set_block_group bgnum field value
397 Modify the block group descriptor specified by
399 so that the block group descriptor field
407 as in use in the inode bitmap.
409 .I set_inode_field filespec field value
410 Modify the inode specified by
412 so that the inode field
416 The list of valid inode fields which can be set via this command
417 can be displayed by using the command:
418 .B set_inode_field -l
420 .I set_super_value field value
421 Set the superblock field
425 The list of valid superblock fields which can be set via this command
426 can be displayed by using the command:
427 .B set_super_value -l
429 .I show_super_stats [-h]
430 List the contents of the super block and the block group descriptors. If the
432 flag is given, only print out the superblock contents.
435 Display the contents of the inode structure of the inode
438 .I testb block [count]
439 Test if the block number
441 is marked as allocated in the block bitmap.
442 If the optional argument
446 blocks starting at block number
453 is marked as allocated in the inode bitmap.
455 .I undel <inode num> [pathname]
456 Undelete the specified inode number (which must be surrounded by angle
457 brackets) so that it and its blocks are marked in use, and optionally
458 link the recovered inode to the specified pathname. The
460 command should always be run after using the
462 command to recover deleted files.
464 Note that if you are recovering a large number of deleted files, linking
465 the inode to a directory may require the directory to be expanded, which
466 could allocate a block that had been used by one of the
467 yet-to-be-undeleted files. So it is safer to undelete all of the
468 inodes without specifying a destination pathname, and then in a separate
469 pass, use the debugfs
471 command to link the inode to the destination pathname, or use
473 to check the filesystem and link all of the recovered inodes to the
477 Remove the link specified by
479 to an inode. Note this does not adjust the inode reference counts.
481 .I write source_file out_file
482 Create a file in the filesystem named
484 and copy the contents of
486 into the destination file.
487 .SH ENVIRONMENT VARIABLES
489 .B DEBUGFS_PAGER, PAGER
492 program always pipes the output of the some commands through a
493 pager program. These commands include:
494 .IR show_super_stats ,
496 .IR show_inode_info ,
497 .IR list_deleted_inodes ,
500 The specific pager can explicitly specified by the
502 environment variable, and if it is not set, by the
504 environment variable.
506 Note that since a pager is always used, the
508 pager is not particularly appropriate, since it clears the screen before
509 displaying the output of the command and clears the output the screen
510 when the pager is exited. Many users prefer to use the
512 pager for most purposes, which is why the
514 environment variable is available to override the more general
516 environment variable.
519 was written by Theodore Ts'o <tytso@mit.edu>.