bvi man page

bvi, bview — visual editor for binary files

Version

bvi-1.4.0

Synopsis

bvi   [-R] [-c cmd] [-f script] [-s skip] [-e end] [-n lengthfile... bview [-R] [-c cmd] [-f script] [-s skip] [-e end] [-n lengthfile...

Options

file...

A  list  of  filenames.  The first one will be the current file and  will be read   into  the  buffer.  The  cursor  will  be  positioned on the first line of the buffer.  You can get to the other files with the ":next" command.  

-R

"Readonly": The readonly flag is set for all the files, preventing accidental overwriting with a write command.

-s skip

causes bvi to load a file not from the start but from offset skip. Skip offset bytes from the beginning of the input.  By default, offset is interpreted as a decimal number.  With a leading 0x or 0X, offset is interpreted as a hexadecimal number, otherwise, with a leading 0, offset is interpreted as an octal number.  Appending the character b, k, or m to offset causes it to be interpreted as a multiple of 512, 1024, or 1048576, respectively.

-e end

causes bvi to load a file not till end but till address end.

-n length

causes bvi not to load the complete file but only length bytes.

-c cmd

cmd will be  executed  after  the  first file  has been read. If the  cmd  contains spaces  it  must  be enclosed in double quotes (this depends on  the  shell  that  is  used).

-f script

This command provides a means for collecting a series of "ex" (colon) commands into a script file, then using this file to edit other files. Since there is no binary stream editor "bsed", you can use this option to make several global changes in a binary file.

Description

Bvi stands for "Binary VIsual editor". Bvi is a screen oriented editor for binary files; its command set is based on that of the vi(1) text editor. As a binary editor does not have the concept of "lines" there are differences from Vi commands wherever the latter are line orientate.

Comparison

The main differences between Vi and Bvi are:

The screen is divided in three sections or panes: The byte offset (extreme left), the hex pane (middle), and an ascii pane (right) which shows as printable characters those bytes in the hex pane. On an 80 column terminal there will be sixteen hex values and their ASCII values on each screen line.  Note that (as one would expect) the first byte has the offset '0' (zero).

You can toggle between the hex and ascii windows with the tab key (TAB). Toggling between these two windows does not change the current position (offset) within the file.

No "lines" concept: Files are treated as one long stream of bytes.  The characters "newline" and "carriage return" are not special, id est they  never mark the end of lines.  Therefore the lines on the screen do not represent lines in the usual way.  Data is broken across screen lines arbitarily. As a consequence there are no commands in bvi from ex or vi that are based on line numbers, eg "dd", "yy", 'C', 'S', 'o', 'O'. This also changes the meaning of "range" before the ":write" command to a byte offset, ie the command ":100,200w foo" writes all *bytes* (not lines) from offset 100 to offset 200 to the file "foo".

No "text objects": There are also no text-specific arrangements like words, paragraphs, sentences, sections and so on.

Extended "ruler": The bottom line of the screen shows the current address (byte offset) and the current character in these notations:

        octal, hexadecimal, decimal and ascii.

Search patterns: All search commands understand these special characters:

     .    any character
     []   set of characters
     *    zero or more occurrences of previous char or set

But as there is no concept of lines you cannot use the standard symbols ("anchors") for "begin-of-line" ('^') and "end-of-line" ('$'). Searching for the start/end of lines must be done explicitly by adding these special characters to your search pattern using these meta sequences:

        \n   newline
        \r   return
        \t   tab
        \0   binary zero

Additional search commands: Similar to the text search commands there are additional hex-search functions '\' and '#' which allow to search for any byte value. Example:  "\62 76 69" will search for the string "bvi". Spaces between hex value are optional, so searching for "6775636B6573" will find "guckes".

Changing the length of data (insertion, deletion) moves the data to other addresses; this is bad for many cases (eg. databases, program files) and is  thus disabled by default. You can enable this commands by typing

:set memmove

BVI Modes:

Command Mode (Normal Mode):

Input is treated as command.  Note that command mode is the default mode after startup and after escaping from input mode. Use ESC (escape) to cancel a partial (uncompleted) command.

Input Mode:

Input is treated as replacement of current characters or  (after the end of the file) is appended to the current file.  This mode is entered from command mode by typing one of 'i', 'I', 'A', 'r', or 'R'. You can enter the characters from the keyboard (in the ASCII window) or  hexadecimal values (in the HEX window). Type TAB to switch between these two windows. Type ESC to finish the current input and return to command mode. Type CTRL-C to cancel current command abnormally.

Command line mode (Last Line Mode or : mode):

Similar to vi, this mode is entered by typing one of the  characters  : / ? \ # ! The command is terminated and executed by typing a carriage return; to cancel a partially typed command, type ESC to cancel the current command and return to command mode.

Environment

The editor recognizes the environment variable BVIINIT as  a command  (or  list of commands) to run when it starts up. If this variable is undefined, the editor  checks  for  startup commands  in  the  file  ~/.bvirc  file, which you must own. However, if there is a .bvirc owned by you  in  the  current directory,  the  editor takes its startup commands from this file - overriding both the file in your home  directory  and the environment variable.

Terminology

Characters names are abbreviated as follows:
    Abbr.     ASCII     name      aka
    CR        010       carriage return
    ^A        001       control-a
    ^H        008       control-h
    ^I        009       control-i      aka TAB
    ^U        021       control-u
    ^Z        026       control-z
    ESC       027       escape         aka ESC
    DEL       127       delete
    LEFT      ---       left  arrow
    RIGHT     ---       right arrow
    DOWN      ---       down  arrow
    UP        ---       up    arrow

Command Summary

See the Terminology for a summary on key name abbreviations used within the following description of commands.

Abstract:
 Arrow keys move the cursor on the screen within the current window.

Sample commands:
 :version    show version info
 <- v ^ ->   arrow keys move the cursor
 h j k l     same as arrow keys
 u           undo previous change
 ZZ          exit bvi, saving changes
 :q!         quit, discarding changes
 /text       search for text
 ^U ^D       scroll up or down

Counts before bvi commands:
 Numbers may be typed as a prefix to some commands.
 They are interpreted in one of these ways.

  screen column       ⎪
  byte of file        G
  scroll amount       ^D  ^U
  repeat effect       most of the rest

Interrupting, canceling
 ESC         end insert or incomplete command
 DEL         (delete or rubout) interrupts

File manipulation:
 ZZ          if file modified, write and exit;
             otherwise, exit
 :w          write changed buffer to file
 :w!         write changed buffer to file, overriding
             read-only ("forced" write)
 :q          quit when no changes have been made
 :q!         quit and discard all changes
 :e file     edit file
 :e!         re-read current file, discard all changes
 :e #        edit the alternate file
 :e! #       edit the alternate file, discard changes
 :w  file    write current buffer to file
 :w! file    write current buffer to file overriding
             read-only (this "overwrites" the file)
 :sh         run the command as set with option "shell",
             then return
 :!cmd       run the command cmd from "shell", then
             return
 :n          edit next file in the argument list
 :f          show current filename, modified flag,
             current byte offset, and percentage of
             current position within buffer
 ^G          same as :f

Additional edit commands
 You can insert/append/change bytes in ASCII/binary/decimal/ hexadecimal or octal representation. You can enter several (screen) lines of input. A line with only a period (.) in it will terminate the command. You must not type in values greater  than a byte value. This causes an abandonment of the command. Pressing the CR key does not insert a newline - character into the file. If you use ASCII mode you can use the special characters  \n, \r, \t and \0.

  :i aCR      insert bytes (ASCII) at cursor position
  :a bCR      append bytes (Binary) at end of file
  :c hCR      change bytes (hexadecimal) at cursor position

Bit-level operations
 :and n      bitwise 'and' operation with value n
 :or  n      bitwise 'or' operation with value n
 :xor n      bitwise 'xor' operation with value n
 :neg        two's   complement
 :not        logical negation
 :sl i       shift  each byte i bits to the left
 :sr i       shift  each byte i bits to the right
 :rl i       rotate each byte i bits to the left
 :rr i       rotate each byte i bits to the right

Command mode addresses
 :w foo         write current buffer to a file
                named "foo"
 :5,10w foo     copy byte 5 through 100 into as
                file named foo
 :.,.+20w foo   copy the current byte and the next
                20 bytes to foo
 :^,'aw foo     write all bytes from the beginning
                through marker 'a'
 :/pat/,$ foo   search pattern pat and and copy
                through end of file

Positioning within file:
 ^B      backward screen
 ^F      forward  screen
 ^D      scroll down half screen
 ^U      scroll up   half screen
 nG      go to the specified character
         (end default), where n is a decimal address
 /pat    next line matching pat
 ?pat    previous line matching pat
 \hex    jump to next     occurrence of hex string hex
 #hex    jump to previous occurrence of hex string hex
 n       repeat last search command
 N       repeat last search command, but in opposite
         direction

Adjusting the screen:
 ^L      clear and redraw screen
 zCR     redraw screen with current line at top of screen
 z-      redraw screen with current line at bottom of
         screen
 z.      redraw screen with current line at center of
         screen
 /pat/z- search for pattern pat and then move currents
         line to bottom
 ^E      scroll screen down 1 line
 ^Y      scroll screen up   1 line

Marking and returning:
 mx      mark current position with lower-case letter x
         Note: this command works for all lower-case letters
 'x      move cursor to mark x in ASCII section
 `x      move cursor to mark x in HEX section
 ''      move cursor to previous context in ASCII section
 ``      move cursor to previous context in HEX section
 Line positioning:
 H           jump to first      line on screen ("top")
 L           jump to last       line on screen ("low")
 M           jump to middle     line on screen ("middle")
 -           jump onto previous line on screen
 +           jump onto next     line on screen
 CR          same as +
 DOWN or j   next     line, same column
 UP   or k   previous line, same column

Character positioning:
 ^           first byte in HEX window
 $           end of screen line
 l or RIGHT  jump onto next byte (within current
             screen line)
 h or LEFT   jump onto previous byte (within current
             screen line)
 ^H          same as LEFT
 space       same as RIGHT
 fx          find next     occurrence of character x
 Fx          find previous occurrence of character x
 n⎪          jump onto nth byte/character within current
             line

Strings:
 (works similar to the strings(1) command)
 Note:  "Words" are defined as strings of "nonprinting
 characters".
 e       jump to next     end   of word
 w       jump to next     begin of word
 b       jump to previous begin of word
 W       forward to next string delimited with a
         \0 or \n
 B       back to previous string delimited with a
         nonprinting char

Corrections during insert:
 ^H      erase last character (backspace)
 erase   your erase character, same as ^H (backspace)
 ESC     ends insertion, back to command mode

Append and replace:
 A       append at end of file
 rx      replace current bte with char 'x'
 R       enter replace mode; for all subsequent input,
         the current byte is overwritten with the next  input character; leave replace mode with ESC.

Miscellaneous Operations:
 TAB     toggle between ASCII and HEX section

Yank and Put:
 3ySPACE yank 3 characters
 p       insert contents of yank buffer
 o       replace text with content of yank buffer
 P       put back at end of file

Undo, Redo:
 u       undo last change
         Note:  Only the last change can be undone.
         Therefore this commands toggles between the
         last and second-t-last state of the buffer.

Setting Options:
 With the :set command you can set options in bvi

  Option     Default  Description
  autowrite  noaw     Save current file, if modified, if you
                      give a :n, :r or ! command
  columns    cm=16    on an 80 character wide terminal
  ignorecase noic     Ignores letter case in searching
  magic      nomagic  Makes . [ * special in patterns
  memmove    nomm     enables insert and delete commands 
  offset     of=0     adds an offset to the diplayed addresses
  readonly   noro     If set, write fails unless you use ! after command
  scroll     sc=1/2 window
                      Number of lines scrolled by ^U and ^D
  showmode   mo       Displays statusline on bottom of the screen
  terse      noterse  Let you obtain shorter error messages
  window     window=screensize
                      Lines in window, can be reduced at slow terminals
  wordlength wl=4     Length of an ASCII-string found by w, W, b or B
  wrapscan   ws       Searches wrap around past the end of the file
  unixstyle  nous     The representation of ascii characters below
                      32 is displayed in the statusline as shown
                      in ascii(7) if unset rather in DOS-style (^A)

Author

bvi was developed by Gerhard Buergmann, Vienna, Austria Gerhard.Buergmann@puon.at

WWW

Bvi Homepage:  http://bvi.sourceforge.net/ Vi Pages:      http://www.guckes.net/vi/clones.php3                (all about Vi and its clones)

Files

 $HOME/.bvirc          editor startup file  ./.bvirc              editor startup file

Bugs

Bvi does not update the screen when the terminal changes its size.

See Also

vi(1), strings(1), ascii(5)

Referenced By

bmore(1).

BVI Version 1.4.0 25/Aug/2013 User Commands