fsdb_vxfs(1M)fsdb_vxfs(1M)NAME
fsdb_vxfs: fsdb - VxFS file system debugger
SYNOPSIS
inumber] special
DESCRIPTION
The command is a powerful tool that can modify the structural elements
of a file system. When used correctly, it can repair damaged file sys‐
tems. However, when used incorrectly, it can cause serious and possi‐
bly unrepairable damage to a file system.
can analyze VxFS file system problems or repair a damaged VxFS file
system after a crash. A special device special specifies the file sys‐
tem to debug. The command is intended for experienced users only.
can convert block and inumbers into their corresponding disk addresses.
In addition, mnemonic offsets allow access to different parts of an
inode. These greatly simplify the process of correcting control block
entries or descending the file system tree.
By default, numbers are considered decimal. You must prefix octal num‐
bers with and prefix hexadecimal numbers with When using hexadecimal
numbers, it is preferable to follow the number with a space, because
several commands are letters that are also hexadecimal digits. In this
document a pound sign indicates that a number is to be specified.
reads a block at a time and works with raw and block I/O. All I/O is
unbuffered, so changes made to the file system are immediate and
changes made by other processes or by the kernel are immediately seen
by
Options
recognizes the following options:
generic_options
Supported by the generic command. See fsdb(1M).
Specify the VxFS file-system type.
Clear the inode identified by
inumber (non-interactive). Multiple options
accumulate.
Operands
recognizes the following operand:
special Name of the special device that contains the VxFS
file system to debug.
Using Commands and Symbols
It is best to separate each token on a command line with a space.
Although the command parser does not require element separation, there
is no ambiguity in the command language if each token is separated with
a space. For example, the command sets the current position to block
0x23b hexadecimal. The command is invalid, because the command is
parsed as simply a hexadecimal number. The command positions to block
23 decimal, since the command is not ambiguous.
You can separate commands with new lines. You can put multiple com‐
mands on one line and separate them with a dot or a semicolon If multi‐
ple commands are placed on one line, generally only the last command
displays results. This allows positioning commands to be followed by
printing commands or change commands without intermediate printing.
Symbols for the fsdb Command
The following symbols are recognized by the command:
Print summary of commands that display [modify|format] the file
system.
Print summary of commands that display [modify|format] the file
system.
Print summary of commands that display [modify|format] the file
system.
Escape to shell.
Pipe output of to a shell command.
Quit.
string A character string. Inside a character string, a
NULL character can be specified with ``\0''; a
double quote can be specified with ``\"''; and a
backslash can be specified with ``\\ ''.
Add, subtract, multiply, divide, and modulus.
Assignment
An inode in the primary inode list.
An inode in the attribute inode list.
An allocation unit.
A block.
The immediate data area of an inode.
Small directories and symbolic link files (96
bytes or less) are stored directly in the inode
itself, in the area normally occupied by data
block numbers and extent sizes.
An attribute inode.
Current directory block.
A directory entry.
An inode address entry.
A byte.
A half-word (2 bytes)
A word (4 bytes)
A double-word (8 bytes)
General print facility
Simple calculator and base converter
Find a matching pattern in the file system
A fileset.
An inode allocation unit in the primary inode list.
An inode allocation unit in the attribute inode list.
The current usage table.
The object location table.
Map logical file offset to an inode extent.
Reset device.
Print Facility Print Formats
The print facility recognizes the following print formats:
Print as a super-block.
Print as an allocation-unit header.
Print as an auxiliary super-block.
Print as intent-log records.
Print as inodes.
List state table blocks.
Print as typed extent descriptors.
Print as directory entries.
Print as a directory block.
Print as a directory header.
Print as octal words.
Print as octal bytes, half-words, words, or double-words.
Print as hexadecimal words.
Print as hexadecimal bytes, half-words, words, or double-words.
Print as decimal words.
Print as decimal bytes, half-words, words, or double-words.
Print as unsigned words.
Print as unsigned bytes, half-words, words, or double-words.
Print as characters.
Print as fileset headers.
Print as current usage table entries.
Print as an inode allocation unit header.
Print as an object location table extent.
Prints as a BSD quota record.
Print as a device record.
Symbols in Inode Fields
Changes to inode fields can be made symbolically. The following sym‐
bols represent inode fields:
Inode mode field
Inode link count field
Inode user ID Number field
Inode group ID Number field
Low-order word of inode file size field
High-order word of inode file size field
Inode file size field
Inode direct extent data block numbers (0 - 9)
Inode direct extent sizes (0 - 9)
Inode indirect extent data block numbers (0 - 1)
Inode indirect extent size
Inode access time field (seconds)
Inode access time field (microseconds).
Inode change time field (seconds).
Inode change time field (microseconds).
Inode modification time field (seconds).
Inode modification time field (microseconds).
Inode allocation flags field.
Inode generation count field.
Inode mapping type field.
Inode fixed extent size field.
Inode blocks held field.
Inode extended operation flag field.
Inode extended operation data field.
If device, inode device number.
If device, inode major number.
If device, inode minor number.
If directory, inode parent directory.
If regular file, inode reservation.
Inode high-order word of serial number.
Inode low-order word of serial number.
Referencing fileset ID.
Inode number of matching inode.
Indirect attribute inode.
Symbols for Directory Block Fields
Changes to directory block fields can be made symbolically. The fol‐
lowing symbols represent directory block fields:
Total free space (only if in a data block).
Hash chain start (0 through 31, only if in a data block).
Directory entry (variable number of entries).
Number of hash chains.
Symbols for Directory Entry Fields
Changes to directory entry fields can be made symbolically. The fol‐
lowing symbols represent directory entry fields:
Inode number
Entry name
Name length
Record length (only if in a data block)
Name hash next (only if in a data block)
Positions in File Systems and Positioning Commands
maintains several positions in the file system:
· current position
· current primary-inode position (i)
· current attribute-inode position (ai)
· current inode type (i or ai)
· current fileset-header position (fset)
· current allocation-unit position (au)
· current primary-inode allocation-unit (iau) position
· current inode allocation-unit type (iau or aiau)
· current attribute-inode allocation-unit (aiau) position
These are used by various commands. (The au positions are only sup‐
ported on the Version 2 disk layout.)
The following commands are supported:
Set the current position in the file system to the specified
offset in bytes,
half-words, words, or double-words. If it is the
last command on a line, print the byte, half-
word, word, or double-words in hexadecimal.
Set the current position to the specified relative offset
in bytes, half-words, words, or double-words. If
it is the last command on a line, print the byte,
half-word, word, or double-words in hexadecimal.
Set the current position in the file system
to the specified allocation unit (au) position.
Set the current allocation unit position to the
resulting offset. If it is the last command on a
line, print the allocation unit header.
Set the current position in the file system
to the specified position relative to the current
allocation unit (au) position. Set the current
allocation unit position to the resulting offset.
If it is the last command on a line, print the
allocation unit header.
Set the current position in the file system
to the current allocation unit position. If it
is the last command on a line, print the alloca‐
tion unit header.
Set the current position in the file system to the specified
offset in blocks.
Set the current block position to the resulting
offset. The block size is the block size of the
file system. If it is the last command on a
line, print the first word in the block in hexa‐
decimal.
Set the current position to specified relative offset in blocks.
Set the current block position to the resulting
offset. If it is the last command on a line,
print the first word in the block in hexadecimal.
Set the current position to current block position (the block
specified
by the last operation). If it is the last com‐
mand on a line, print the first word in the block
in hexadecimal.
Set the current position to the current usage table (cut).
If it is the last command on a line, print the
first current usage table entry.
Set the current position to the primary device's
configuration record. If it is the last command
on a line, print the device-configuration record.
Set the current position in the file system to the fileset
header entry for
the specified fileset index. Set the current
fileset position to the resulting offset. If it
is the last command on a line, print the speci‐
fied fileset header.
Set the current position in the file system to the fileset
header entry
for the specified position relative to the cur‐
rent fileset position. Set the current fileset
position to resulting offset. If it is the last
command on a line, print the specified fileset
header.
Set the current position in the file system to the current file‐
set position.
If it is the last command on a line, print the
fileset header for the current fileset.
Set the current position in the file system to the specified
attribute inode
allocation unit (aiau) in a fileset. Set the cur‐
rent attribute inode allocation unit position to
the resulting offset. If it is the last command
on a line, print the attribute inode allocation
unit header.
Set the current position in the file system to the specified
position relative
to the current attribute inode allocation unit
(aiau) position. Set the current attribute inode
allocation unit position to the resulting offset.
If it is the last command on a line, print the
attribute inode allocation unit header.
Set the current position in the file system to the current
attribute inode allocation unit (aiau) position.
If it is the last command on a line, print the
attribute inode allocation unit header.
Set the current position in the file system to the specified
inode
allocation unit (iau) in a fileset. Set the cur‐
rent inode allocation unit position to the
resulting offset. If it is the last command on a
line, print the inode allocation unit header.
Set the current position in the file system to the specified
position relative
to the current inode allocation unit (iau) posi‐
tion. Set the current inode allocation unit
position to the resulting offset. If it is the
last command on a line, print the inode alloca‐
tion unit header.
Set the current position in the file system to the current
inode allocation unit (iau) position. If it is
the last command on a line, print the inode allo‐
cation unit header.
Set the current position in the current fileset to the ilist
entry
for the specified attribute inode. Set the cur‐
rent attribute inode position to the resulting
offset. If it is the last command on a line,
print the ilist entry for the inode.
Set the current position in the current fileset to the ilist
entry for the
specified relative attribute inode. Set the cur‐
rent attribute inode position to the resulting
offset. If it is the last command on a line,
print the ilist entry for the inode.
Set the current position in the current fileset
to the current attribute inode position. If it
is the last command on a line, print the ilist
entry for the inode.
Set the current position in the current fileset to the ilist
entry
for the specified inode. Set the current inode
position to the resulting offset. If it is the
last command on a line, print the ilist entry for
the inode.
Set the current position in the current fileset to the ilist
entry for the
specified relative inode. Set the current inode
position to the resulting offset. If it is the
last command on a line, print the ilist entry for
the inode.
Set the current position in the current fileset to the current
inode position.
If it is the last command on a line, print the
ilist entry for the inode.
Set the current position to specified offset in blocks specified
by the
inode address #. Addresses 0 through 9 are for
direct extents ( de ). Addresses 10-11 are for
indirect extents ( ie ). The addresses are dis‐
played when printing an ilist entry. Set the
current block position to the resulting offset.
If it is the last command on a line, print the
first word in the block in hexadecimal.
Set the current position to immediate data area of the current
inode.
Set the current block position to the resulting
offset. If it is the last command on a line,
print the first word of the area in hexadecimal.
Set the current position to attribute data area of the current
inode.
Set the current block position to the resulting
offset. If it is the last command on a line,
print the first word in the block in hexadecimal.
Set the current position and change the number at the specified
offset
to the given number. If a double-word offset is
specified, then two numbers separated by a space
are required. The resulting value is printed in
hexadecimal.
Set the current position and change the number at the specified
relative offset
to the given number. If a double-word offset is
specified, then two numbers separated by a space
are required. The resulting value is printed in
hexadecimal.
Set the current position and change the characters at the speci‐
fied offset
to the given string. The resulting value is
printed as a character string.
Set the current position and change the characters at the speci‐
fied relative
offset to the given string. The resulting value
is printed as a character string.
Set the current position to the object location table (olt).
If it is the last command on a line, print the
object location table.
Print the contents of the file system at the current offset as
the
specified number of entries of a given format.
The allowable print formats are specified above.
If a number of entries to print is not specified,
one entry is printed.
Set the contents of the given inode field to the specified num‐
ber.
The current inode specifies the inode list entry
to be modified. The symbols representing inode
fields are listed above.
Set the contents of the given directory block field to the spec‐
ified
number. The current block is treated as a direc‐
tory block and the offset in that block which is
represented by the given field is changed. The
symbols representing directory block fields are
listed above.
Set the current directory entry to the specified number.
The current block is treated as a directory
block. If the current block is an immediate data
area for an inode, then the block is treated as
containing immediate directory entries. If it is
the last command on a line, the directory entry
at the resulting offset is printed.
Set the contents of the given directory field to the specified
number.
The current directory entry specifies where the
directory entry is located. The resulting value
is printed in hexadecimal.
Set the directory name field of the current directory entry to
the specified string. The resulting value is
printed as a character string.
Take a number or the sum, difference, product or dividend of two
numbers
and print in decimal, octal, hexadecimal and
character format.
Search for the given numeric pattern in the file system.
The size of the object to match is specified. If
a double-word is specified, then two numbers must
be given. The search is performed forward from
the current offset. A maximum number of blocks
to search can be specified. If found, the loca‐
tion and value are printed in hexadecimal.
Search for the given character string in the file system.
The search is performed forward from the current
offset. A maximum number of blocks to search can
be specified. If found the location and string
are printed.
Format all intent log entries. A completely formatted intent log
can be quite lengthy. It is a good idea use the
command as a filter and redirect the output to a
file or pager to look at a complete log format.
List all filesets by their indexes and names.
Treat the number as a logical offset in the file described by
the current inode, and print the extent that it
maps to.
Does the equivalent of exiting
and restarting on same device.
Help Commands
The following help commands are supported:
Display primary help screen.
Display modification-commands help screen.
Display print-commands help screen.
EXAMPLES
Prints inumber 386 in an inode format.
This now becomes the current working inode.
Changes the link count for the
working inode to 4.
Prints the super-block of this file system symbolically.
Changes the name field
in the directory slot to foo.
Changes the inumber for the
seventh directory slot in the root directory to three
(also shows how to combine several operations on one
command line)
Prints the sixth directory entry in the immediate area of inode 23.
WARNINGS
Always run a file system check (see fsck(1M)) after using the command
to modify a file system. (Use
Some aspects of apply to a specific VxFS disk layout version.
SEE ALSOfsck_vxfs(1M), fsdb(1M).
fsdb_vxfs(1M)
