fsdb_udfs(1M)
NAME
fsdb_udfs - udfs file system debugger
SYNOPSIS
fsdb [-F] udfs [generic_option] [-o specific_option] spe-
cial
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 neces-
sary 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 commonly 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 pro-
mote 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 follow-
ing 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. Hexa-
decimal numbers beginning with a-f or A -F must be preceded
with a 0x to distinguish 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 execu-
tion. For example,
> 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
expression. Specify numeric expressions using addi-
tion, subtraction, 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. Multi-
plication 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 sin-
gle letter or digit.
= f Display indicator. If f is a legitimate format specif-
ier (see Formatted Output), then the value of dot is
displayed using format specifier f. Otherwise, assign-
ment 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 changing directory names or ASCII file
information.
=+ e Change the value of dot using an incremental assign-
ment. The address pointed to by dot has its contents
incremented by expression e.
=- e Change the value of dot using a decremental assign-
ment. 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 supports the cd, pwd, ls, and find commands. The func-
tionality of each of these commands basically matches that
of its UNIX counterpart. See cd(1), pwd(1),ls(1), and-
find(1) for details. The *, ,, ?, and - wildcard 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. Otherwise, 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 direc-
tory, 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 suc-
cessful, 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 speci-
fied before the filename specifiers). Wild card char-
acters 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 overridden if override is toggled to on. ""
.nr )I p""n
prompt
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 volume 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 display 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. Unstructured output displays raw
data.
Format specifiers are preceded by the slash (/) or question
mark (?) character. type is updated as necessary upon com-
pletion.
The following format specifiers are preceded by the ? char-
acter:
i Display as inodes in the current base.
d Display as directories in the current base.
The following format specifiers are preceded by the / char-
acter:
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 example 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 hex-
adecimal long
The following command displays the creation time as a hexa-
decimal 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 associated 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 direc-
tory 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 attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWudf |
|_____________________________|_____________________________|
SEE ALSO
clri(1M), fsck_udfs(1M), dir(4), attributes(5)
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