fsdb_udfs(1M) System Administration Commands fsdb_udfs(1M)NAMEfsdb_udfs - udfs file system debugger
SYNOPSIS
fsdb [-F] udfs [generic_option] [-o specific_option] special
DESCRIPTION
The fsdb_udfs command is an interactive tool that can be used to patch
up a damaged udfs file system. fsdb_udfs has conversions to translate
block and i-numbers into their corresponding disk addresses. Mnemonic
offsets to access different parts of an inode are also included.
Mnemonic offsets greatly simplify the process of correcting control
block entries or descending the file system tree.
fsdb contains several error-checking routines to verify inode and block
addresses. These can be disabled if necessary by invoking fsdb with the
-o option or by using the o command.
fsdb reads one block at a time, and therefore works with raw as well as
block I/O devices. A buffer management routine is used to retain com‐
monly used blocks of data in order to reduce the number of read system
calls. All assignment operations result in an immediate write-through
of the corresponding block. In order to modify any portion of the disk,
fsdb must be invoked with the -w option.
Wherever possible, adb-like syntax has been adopted to promote the use
of fsdb through familiarity.
OPTIONS
The following options are supported:
-o specific_option Specify udfs file system specific options in a
comma-separated list with no intervening spaces.
The following specific options are supported:
o Override some error conditions.
p=string Set prompt to string.
w Open for write.
? Display usage.
USAGE
Numbers are considered hexadecimal by default. The user has control
over how data is to be displayed or accepted. The base command displays
or sets the input and output base. Once set, all input defaults to this
base and all output displays in this base. The base can be overriden
temporarily for input by preceding hexadecimal numbers by 0x, preceding
decimal numbers with a 0t, or octal numbers with a 0. Hexadecimal num‐
bers beginning with a-f or A -F must be preceded with a 0x to distin‐
guish them from commands.
Disk addressing by fsdb is at the byte level. However, fsdb offers many
commands to convert a desired inode, directory entry, block, and so
forth, to a byte address. After the address has been calculated, fsdb
records the result in the current address (dot).
Several global values are maintained by fsdb:
o Current base (referred to as base)
o Current address (referred to as dot)
o Current inode (referred to as inode)
o Current count (referred to as count)
o Current type (referred to as type)
Most commands use the preset value of dot in their execution. For exam‐
ple,
> 2:inode
first sets the value of dot (.) to 2, colon (:), signifies the start of
a command, and the inode command sets inode to 2. A count is specified
after a comma (,). Once set, count remains at this value until a new
command is encountered that resets the value back to 1 (the default).
So, if
> 2000,400/X
is entered, 400 hex longs are listed from 2000, and when completed, the
value of dot is 2000 + 400 * sizeof (long). If a RETURN is then
entered, the output routine uses the current values of dot, count, and
type and displays 400 more hex longs. An asterisk (*) causes the entire
block to be displayed. An example showing several commands and the use
of RETURN would be:
> 2:ino; 0:dir?d
or
> 2:ino; 0:db:block?d
The two examples are synonymous for getting to the first directory
entry of the root of the file system. Once there, subsequently entering
a RETURN, plus (+), or minus (-) advances to subsequent entries.
Notice that
> 2:inode; :ls
or
> :ls /
is again synonymous.
Expressions
The following symbols are recognized by fsdb:
RETURN Update the value of dot by the current value of type and
display using the current value of count.
# Update the value of dot by specifying a numeric expres‐
sion. Specify numeric expressions using addition, subtrac‐
tion, mulitiplication, and division operators ( +, -, *,
and %). Numeric expressions are evaluated from left to
right and can use parentheses. After evaluation, the value
of dot is updated.
, count Update the count indicator. The global value of count is
updated to count. The value of count remains until a new
command is run. A count specifier of * attempts to show a
blocks's worth of information. The default for count is 1.
? f Display in structured style with format specifier f. See
Formatted Output.
/ f Display in unstructured style with format specifier f. See
Formatted Output.
. Display the value of dot.
+e Increment the value of dot by the expression e. The amount
actually incremented is dependent on the size of type: dot
= dot + e * sizeof (type) The default for e is 1.
−e Decrement the value of dot by the expression e . See +.
*e Multiply the value of dot by the expression e. Multiplica‐
tion and division don't use type. In the above calculation
of dot, consider the sizeof (type) to be 1.
%e Divide the value of dot by the expression e. See *.
< name Restore an address saved in register name. name must be a
single letter or digit.
> name Save an address in register name. name must be a single
letter or digit.
= f Display indicator. If f is a legitimate format specifier
(see Formatted Output), then the value of dot is displayed
using format specifier f. Otherwise, assignment is
assumed. See = [s] [e].
= [s] [e] Change the value of dot using an assignment indicator. The
address pointed to by dot has its contents changed to the
value of the expression e or to the ASCII representation
of the quoted (") string s. This can be useful for chang‐
ing directory names or ASCII file information.
=+ e Change the value of dot using an incremental assignment.
The address pointed to by dot has its contents incremented
by expression e.
=- e Change the value of dot using a decremental assignment.
Decrement the contents of the address pointed to by dot by
expression e.
Commands
A command must be prefixed by a colon (:). Only enough letters of the
command to uniquely distinguish it are needed. Multiple commands can be
entered on one line by separating them by a SPACE, TAB, or semicolon
(;).
To view a potentially unmounted disk in a reasonable manner, fsdb sup‐
ports the cd, pwd, ls, and find commands. The functionality of each of
these commands basically matches that of its UNIX counterpart. See
cd(1), pwd(1),ls(1), andfind(1) for details. The *, ,, ?, and - wild‐
card characters are also supported.
The following commands are supported:
base[=b]
Display or set the base. All input and output is governed by the
current base. Without the = b, displays the current base. Other‐
wise, sets the current base to b. Base is interpreted using the old
value of base, so to ensure correctness use the 0, 0t, or 0x prefix
when changing the base. The default for base is hexadecimal.
block
Convert the value of dot to a block address.
cd [dir]
Change the current directory to directory dir. The current values
of inode and dot are also updated. If dir is not specified, changes
directories to inode 2, root (/).
directory
If the current inode is a directory, converts the value of dot to a
directory slot offset in that directory, and dot now points to this
entry.
file
Set the value of dot as a relative block count from the beginning
of the file. The value of dot is updated to the first byte of this
block.
find dir [-name n] | [-inum i]
Find files by name or i-number. Recursively searches directory dir
and below for file names whose i-number matches i or whose name
matches pattern n. Only one of the two options (-name or -inum) can
be used at one time. The find -print is not necessary or accepted.
fill=p
Fill an area of disk with pattern p. The area of disk is delimited
by dot and count.
inode
Convert the value of dot to an inode address. If successful, the
current value of inode is updated as well as the value of dot. As a
convenient shorthand, if :inode appears at the beginning of the
line, the value of dot is set to the current inode and that inode
is displayed in inode format.
ls [ -R ] [-l ] pat1 pat2...
List directories or files. If no file is specified, the current
directory is assumed. Either or both of the options can be used
(but, if used, must be specified before the filename specifiers).
Wild card characters are available and multiple arguments are
acceptable. The long listing shows only the i-number and the name;
use the inode command with ?i to get more information.
override
Toggle the value of override. Some error conditions might be over‐
ridden if override is toggled to on.
prompt "p"
Change the fsdb prompt to p. p must be enclosed in quotes.
pwd
Display the current working directory.
quit
Quit fsdb.
tag
Convert the value of dot and if this is a valid tag, print the vol‐
ume structure according to the tag.
!
Escape to the shell.
Inode Commands
In addition to the above commands, several other commands deal with
inode fields and operate directly on the current inode (they still
require the colon (:). They can be used to more easily display or
change the particular fields. The value of dot is only used by the :db
and :ib commands. Upon completion of the command, the value of dot is
changed so that it points to that particular field. For example,
> :ln=+1
increments the link count of the current inode and sets the value of
dot to the address of the link count field.
The following inode commands are supported:
at Access time
bs Block size
ct Creation time
gid Group id
ln Link number
mt Modification time
md Mode
maj Major device number
min Minor device number
nm This command actually operates on the directory name field.
Once poised at the desired directory entry (using the
directory command), this command allows you to change or dis‐
play the directory name. For example,
> 7:dir:nm="foo"
gets the 7th directory entry of the current inode and changes
its name to foo. Directory names cannot be made larger than the
field allows. If an attempt is made to make a directory name
larger than the field allows,, the string is truncated to fit
and a warning message is displayed.
sz File size
uid User ID
uniq Unique ID
Formatted Output
Formatted output comes in two styles and many format types. The two
styles of formatted output are: structured and unstructured. Structured
output is used to display inodes, directories, and so forth. Unstruc‐
tured output displays raw data.
Format specifiers are preceded by the slash (/) or question mark (?)
character. type is updated as necessary upon completion.
The following format specifiers are preceded by the ? character:
i Display as inodes in the current base.
d Display as directories in the current base.
The following format specifiers are preceded by the / character:
b Display as bytes in the current base.
c Display as characters.
o | O Display as octal shorts or longs.
d | D Display as decimal shorts or longs.
x | X Display as hexadecimal shorts or longs.
EXAMPLES
Example 1 Using fsdb as a calculator for complex arithmetic
The following command displays 2010 in decimal format, and is an exam‐
ple of using fsdb as a calculator for complex arithmetic.
> 2000+400%(20+20)=D
Example 2 Using fsdb to display an i-number in idode fomat
The following command displays the i-number 386 in inode format.386
becomes the current inode.
> 386:ino?i
Example 3 Using fsdb to change the link count
The following command changes the link count for the current inode to
4.
> :ln=4
Example 4 Using fsdb to increment the link count
The following command increments the link count by 1.
> :ln=+1
Example 5 Using fsdb to display the creation time as a hexadecimal long
The following command displays the creation time as a hexadecimal long.
> :ct=X
Example 6 Using fsdb to display the modification time in time format
The following command displays the modification time in time format.
> :mt=t
Example 7 Using fsdb to display in ASCII
The following command displays, in ASCII, block 0 of the file associ‐
ated with the current inode.
> 0:file/c
Example 8 Using fsdb to display the directory enteries for the root
inode
The following command displays the first block's directory entries for
the root inode of this file system. This command stops prematurely if
the EOF is reached.
> 2:ino,*?d
Example 9 Using fsdb to change the current inode
The following command changes the current inode to that associated
with the 5th directory entry (numbered from 0) of the current inode.
The first logical block of the file is then displayed in ASCII.
> 5:dir:inode; 0:file,*/c
Example 10 Using fsdb to change the i-number
The following command changes the i-number for the 7th directory slot
in the root directory to 3.
> 2:inode; 7:dir=3
Example 11 Using fsdb to change the name field
The following command changes the name field in the directory slot to
name.
> 7:dir:nm="name"
Example 12 Using fsdb to display the a block
The following command displays the 3rd block of the current inode as
directory entries.
Example 13 Using fsdb to set the contents of address
The following command sets the contents of address 2050 to 0xffffffff.
0xffffffff can be truncated, depending on the current type.
> 2050=0xffff
Example 14 Using fsdb to place an ASCII string at an address
The following command places the ASCII string this is some text at
address 1c92434.
> 1c92434="this is some text"
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │system/file-system/udfs │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOclri(1M), fsck_udfs(1M), dir(4), attributes(5)SunOS 5.11 11 Jun 1999 fsdb_udfs(1M)
