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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 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:
- Current base (referred to as base)
- Current address (referred to as dot)
- Current inode (referred to as inode)
- Current count (referred to as count)
- Current type (referred to as type)
Most commands use the preset value of dot in their execution. For example, 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 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: or 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 or is again synonymous.
Expressions
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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 addition, 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. Multiplication 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 changing 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.
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Commands
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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 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 - 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 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 overridden 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 volume structure according to the tag.
- !
- Escape to the shell.
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Inode Commands
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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, 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, 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
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Formatted Output
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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 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.
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