DHEX(1) BSD General Commands Manual DHEX(1)NAMEdhex — hex editor with a diff mode
SYNOPSISdhex [-h] [-v] [-g] [-k] [-ab -ad -ah -ao base address] [-f config-file]
[-m marker-file] [-ob -od -oh -oo offset] [-r searchlog]
[-sa -sab string (ascii)] [-sh -shb string (hex)] [-w searchlog]
[file]
dhex [-h] [-v] [-g] [-k] [-a1b -a1d -a1h -a1o base address 1]
[-a2b -a2d -a2h -a2o base address 2] [-cb] [-cd upper-limit] [-cl]
[-f config-file] [-m marker-file] [-o1b -o1d -o1h -o1o offset1]
[-o2b -o2d -o2h -o2o offset2] [-r1 searchlog1] [-r2 searchlog2]
[-s1a -s1ab -s1h -s1hb string (ascii/hex)]
[-s2a -s2ab -s2h -s2hb string (ascii/hex)] [-w1 searchlog1]
[-w2 searchlog2] [file1 file2]
DESCRIPTIONdhex is a hex editor. It can be used to alter individual bytes in large
files. Since it is a text-mode programm based on ncurses, it can run in
numerous scenarios. Its special feature is the diff mode: With it, the
user has a visual tool for file comparison. This mode is invoked when
dhex is called with two instead of one file as parameters.
OPTIONS
All the options are case-insensitive and can be given as either upper- or
lowercase characters.
-ab -ad -ah -ao base address
After loading a file, every address gets a base address other
than 0. With this, it is easier to work on partial memory
dumps. The base address can be given as a binary one with
[-ab] , as a decimal one with [-ad] , as a hexadecimal one
with [-ah] or an octal with [-ao].
-a1b -a1d -a1h -a1o base address 1
-a2b -a2d -a2h -a2o base address 2
For the diff mode, it is possible to set two different base
addresses. Again, a binary address can be given as [-a1b
-a2b] , as decimal one with [-a1d -a2d] , as hexadecimal one
with [-a1h -a2h] or an octal one with [-a1o -a2o].
This base address is calculated into the marker files as well
as the searchlogs.
-cb -cl Diff mode only: The input files can be correlated from the
command line with the best -cb or longest -cl match. This is
very slow.
-cd upper-limit
Diff mode only: The input files can be correlated from the
command line with the minimum difference. To improve the cor‐
relation speed, an upper limit can be provided.
-f configfile
Usually, .dhexrc is being read from the invoker's home direc‐
tory. With this parameter, any other config file can be
loaded. See dhexrc(5) for a description of its file format.
-g Shows the license
-h Shows the help screen
-k Starts the keyboard setup manually before any file is being
loaded. This is very helpful when calling dhex from an exotic
terminal.
-m markerfile
It is possible in dhex to set bookmarks and store them in a
markerfile for later use. With this parameter, the markerfile
is being read at start time, making it unnecesarry to read
them later through the gui. Their file format is described in
dhex_markers(5).
-ob -od -oh -oo offset
After loading a file, the cursor is set to 0, and the first
page of bytes is being shown on the screen. With one of those
parameters it is possible to start at any other location in
the file. The cursorposition could be given as a binary num‐
ber with [-ob] , as a decimal one with [-od] , as a hexadeci‐
mal one with [-oh] or an octal with [-oo].
-o1b -o1d -o1h -o1o offset1
-o2b -o2d -o2h -o2o offset2
For the diff mode, it is possible to set two different cur‐
sorpositions at start time. Again, the cursorpositions can be
given as a binary number with [-o1b -o2b] , as decimal one
with [-o1d -o2d] , as hexadecimal one with [-o1h -o2h] or an
octal one with [-o1o -o2o].
This way, the first few bytes in a file can be skipped, and
just the rest can be compared.
-r searchlog
When searching from the command line, the offsets are being
read from this searchlog. Its format is being decribed in
dhex_searchlog(5).
-r1 searchlog1
-r2 searchlog2
When searching in two files simultanously, the offsets can be
read from two different searchlogs.
-sa -sab -sh -shb string
Instead of setting the cursor offset to an absolute value, it
is possible to search for a specific string from the command
line. If there is an additional [-ob -od -oh -oo offset]
present, the search will start there. It is possible to read
and write search logs with [-r searchlog] and [-w searchlog]
respectively. With [-sa string] is being interpreted as
ASCII. [-sh string] interprets it as hex. For backwards
search, [-sab string] or [-shb string] can be applied.
-s1a -s1ab -s1h -s1hb string1
-s2a -s2ab -s2h -s2hb string2
In the diff mode, it is possible to search for two strings in
two files simultanously.
-v Prints out the version of dhex.
-w searchlog
When searching from the command line, write the results into
this searchlog and quit. It is being written in the format
described in dhex_searchlog(5.)
-w1 searchlog1
-w2 searchlog2
When searching in two files simultanously, write the results
from both searches into those log files.
USER INTERFACE
General
Menus have hotkeys, they are being presented in a different color. To
jump from one menu item to the next, the cursor keys or the TAB key can
be used.
Input fields can be closed by pressing ESC, ENTER, or any cursor key.
Only pressing ESC will not save the changes made in there.
The keyboard setup
When running dhex for the first time, without any configfile present, or
with the parameter -k, the first screen shown is that of the keyboard
setup. In this screen, the program asks the user to press certain keys.
Which are (in order) ESCAPE, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10,
BACKSPACE, DEL, ENTER, TAB, UP, DOWN, RIGHT, LEFT, PG UP, PG DOWN, HOME,
END. It also tells the user what it intends to do with those keys later.
So the user can decide on any alternative he chooses. If he does not
want to bind a specific function to a certain key, he can simply press
ESCAPE and skip to the next question.
After pressing all the keys, the user can chose whether or not to write
those keys into the config file.
The main screen
The main screen is broken down into three columns: The first column con‐
tains the offset within the file for the current line. The second column
contains the bytes in the file in hex format. Finally, the third coumn
contains the same bytes, but this time in ascii format. If a byte is not
printable, it is being substituted with a '.'. How many bytes are are
being shown in a line depends on the width of the terminal. For example,
if the terminal is 80 characters wide, 16 bytes are being shown in each
line.
If no other [-o] or [-a] parameter was given at start time, the cursor is
being set to offset 0. It is also being shown in the hex column. Here, it
can be moved with the cursor keys. When entering a hexadecimal number,
the file is being edited. The file can be edited in the ascii column as
well, simply by pressing the TAB key (or whichever key was substituted
for it in the keyboard setup). Pressing TAB again will return the cursor
to the hex column. Pressing F9 (or its substitute) will undo the last of
the changes. Changes are being shown in a differnt color.
Editing is not possible in the diff mode. Here, pressing the cursor keys
will move both files synchronously.
The goto screen
Pressing F1 (or its substitute) will open the Goto... screen. Here, it is
possible to jump to a specific address directly, without the need of
scrolling there with the cursor keys. The address can be entered in the
'To' field, either absolute or relative (to leap over a specified amount
of bytes). An absolute address is being chosen by pressing '=', and a
relative one by pressing '+' or '-', for a positive or negative leap
respectively. Regardless of the adressing mode, it has to be entered as a
hexadecimal number.
It is also possible to set up to ten bookmarks in this screen: Pressing
'0'...'9' will select one of them. Moving the cursor to "Set" and press‐
ing ENTER will alter one of those book marks. The "Diff:" fields are
showing the difference between the actual cursor position and the book‐
mark.
Bookmarks can be stored and loaded, for this there are the "Save Markers"
and "Load Markers" items on the bottom. Upon selecting one of them, the
user is being prompted for a filename. It is possible to load a marker
file at start time, by providing the [-m markerfile] parameter.
dhex_markers(5) describes the format of the marker files.
Searching
Pressing F2 (or its subsitute) will open the Search... screen. Here, a
short string can be entered (either in hex, or in ascii). If no logfiles
are being selected, the cursor will jump to the next occurance of this
search string upon selection of "Go". It can be chosen if the search is
supposed to be conducted forward of backwards.
To jump to the next occurance, F3 (or its substitute) has to be pressed.
To jump to the previous one, F4 has to be pressed. The search itself
wraps at the edges of the file, meaning that when it reaches the end, it
will start from the beginning and vice versa.
Searchlogs are an advanced way of searching: Writing to the searchlog
does not jump the cursor from one occurance to the next. Instead, it will
write the offsets of all of them into the logfile. Their format is
described in dhex_searchlog(5).
Reading from this searchlog means that the search does not cover the
whole file: Only the addresses which have been provided in this file are
being searched. Thus it is possible to search for specific changes. Like
for example the number of lives stored in the save file of a game.
dhex_searchlog(5) describes the format of the searchlog.
HexCal
Pressing F5 (or its substitute) will open a small 64 bit calculator. This
calculator is capable of not only performing arithmetic operations (+,
-, *, /, modulo), but also logic ones. (and, or, xor, shift). There are
three columns to enter numbers as hexadecimals, decimals or in binary
format. Pressing 'x' will close this screen.
Correlation
When dhex(1) is running in diff mode, pressing F6 (or its substitute)
will open the dialog for file correlation. This will try to find the
optimal offset between the two files. There are three algorithms avail‐
able for finding this offset: Searching for the best match (as many bytes
as possible are the same), the longest match (as many consecutive bytes
match as possible), or the minimum difference (as little differences
between the bytes as possible).
Even though it seems like the same at first, looking for the minimum dif‐
ference is in fact faster. This can be improved even more, if the user
sets an upper difference limit.
Upon selecting Go, the program will search for the optimal offset. This
will take some time.
Saving and quitting
Pressing F10 (or its substitute) will close dhex. In case there have
been changes made to the file, a save dialog opens up. Here, it is possi‐
ble to select whether or not to write the changes back into the file.
FILES
$HOME/.dhexrc: The default location of the config file. If the $HOME-
variable is not set, its location has to be provided manually.
BUGS
Report bugs to ⟨dettus@dettus.net⟩. Make sure to include DHEX somewhere
in the subject.
AUTHOR
Written by Thomas Dettbarn
SEE ALSOdhexrc(5), dhex_markers(5), dhex_searchlog(5)BSD May 12, 2012 BSD
