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Apologies for any typos, and IF this has been done before...

The code generates a 256 byte binary file of _characters_ 0x00 to 0xFF for general usage and generates another binary file manipulated in a basic way.

The for loops in the code are purely for DEMO purposes only.

This is Public Domain and you may do with it as you please. I have uploaded it elsewhere too...

Watch for wordwrapping, etc and read the code for more information...

Enjoy finding simple solutions to often very difficult problems...

Bazza, G0LCU...

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# !/bin/sh
#
# BFM.sh
# A very simple DEMO Binary File Manipulation shell code issued entirely as Public Domain.
#
# Apologies for any typos...
#
# This is a DEMO to show how to generate binaryfiles in the shell.
# I need this facility for a kids project I am doing. It will be posted onto here in
# the not too distant future...
#
# To run, ensure the script is executable and from a terminal type:-
#
# *****$ /absolute/path/to/BFM.sh<CR>
#
# And away you go...
#
# Many thanks to MartyBartFast of the Linux Format forums for reminding me of the backticks... ;o)
#
# Written so that kids and newbies can understand what is going on...
#
# $VER: BFM.sh_Version_0.00.10_Public_Domain_2013_B.walker_G0LCU.
#
# Enjoy finding simple solutions to often very difficult problems...

# These two files WILL be generated inside YOUR default /directory/drawer/folder/...
# Zero them as a starter JUST for this DEMO...
> SomeBinaryFile.dat
> MyBinaryFile.dat

# This loop is to give a usable 256 byte binary file only from 0x00 to 0xFF continuous...
clear
for character in {0..255}
do
	# Note:- The backticks and the four escape characters are required...
	char=`printf '\\\\x'"%02x" $character`
	printf "$char" >> SomeBinaryfile.dat
done

# Do a hexadecimal dump to prove the file is binary and 256 bytes in size...
printf "\nOffset.                    Hexadecimal Dump.                    ASCII Dump.\n"
hexdump -C SomeBinaryFile.dat

# Now this EXAMPLE loop is the working loop. The three variables set the "start", (_offset_), of where you want
# your file to start, the "jump" between each _sample_ and the last_byte_limit to where you want to finish...
# IMPORTANT!!! There is NO error detection or correction in the code as it is a DEMO so don't come back and
# say that you can crash it, e.g. setting the "last_byte_limit" to -1 for example...
# Also although I am using a "for" loop for this DEMO you could select a single byte manually and code accordingly...
#
# The _variables_ for this DEMO. The jump is set to every seventh byte for this DEMO.
start_offset=4
jump=7
last_byte_limit=200

# _hexdump_ is used to select the byte(s) according to this DEMO "for" loop...
for subscript in $( seq $start_offset $jump $last_byte_limit )
do
	number=`hexdump -n1 -s$subscript -v -e '1/1 "%u"' SomeBinaryFile.dat`
	char=`printf '\\\\x'"%02x" $number`
	printf "$char" >> MyBinaryFile.dat
done
# Now display it...
printf "\nOffset.                    Hexadecimal Dump.                    ASCII Dump.\n"
hexdump -C MyBinaryFile.dat

# A terminal window dump of what should occur...
#
# Offset.                    Hexadecimal Dump.                    ASCII Dump.
# 00000000  00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f  |................|
# 00000010  10 11 12 13 14 15 16 17  18 19 1a 1b 1c 1d 1e 1f  |................|
# 00000020  20 21 22 23 24 25 26 27  28 29 2a 2b 2c 2d 2e 2f  | !"#$%&'()*+,-./|
# 00000030  30 31 32 33 34 35 36 37  38 39 3a 3b 3c 3d 3e 3f  |0123456789:;<=>?|
# 00000040  40 41 42 43 44 45 46 47  48 49 4a 4b 4c 4d 4e 4f  |@ABCDEFGHIJKLMNO|
# 00000050  50 51 52 53 54 55 56 57  58 59 5a 5b 5c 5d 5e 5f  |PQRSTUVWXYZ[\]^_|
# 00000060  60 61 62 63 64 65 66 67  68 69 6a 6b 6c 6d 6e 6f  |`abcdefghijklmno|
# 00000070  70 71 72 73 74 75 76 77  78 79 7a 7b 7c 7d 7e 7f  |pqrstuvwxyz{|}~.|
# 00000080  80 81 82 83 84 85 86 87  88 89 8a 8b 8c 8d 8e 8f  |................|
# 00000090  90 91 92 93 94 95 96 97  98 99 9a 9b 9c 9d 9e 9f  |................|
# 000000a0  a0 a1 a2 a3 a4 a5 a6 a7  a8 a9 aa ab ac ad ae af  |................|
# 000000b0  b0 b1 b2 b3 b4 b5 b6 b7  b8 b9 ba bb bc bd be bf  |................|
# 000000c0  c0 c1 c2 c3 c4 c5 c6 c7  c8 c9 ca cb cc cd ce cf  |................|
# 000000d0  d0 d1 d2 d3 d4 d5 d6 d7  d8 d9 da db dc dd de df  |................|
# 000000e0  e0 e1 e2 e3 e4 e5 e6 e7  e8 e9 ea eb ec ed ee ef  |................|
# 000000f0  f0 f1 f2 f3 f4 f5 f6 f7  f8 f9 fa fb fc fd fe ff  |................|
# 00000100
#
# Offset.                    Hexadecimal Dump.                    ASCII Dump.
# 00000000  04 0b 12 19 20 27 2e 35  3c 43 4a 51 58 5f 66 6d  |.... '.5<CJQX_fm|
# 00000010  74 7b 82 89 90 97 9e a5  ac b3 ba c1 c8           |t{...........|
# 0000001d
# Barrys-MacBook-Pro:~ barrywalker$ 
#
# BFM.sh DEMO end...
# Enjoy finding simple solutions to often very difficult problems...

I need bnary manipulation and thought that this snippet might be of use to anyone requiring the same in a *NIX shell script...

Bazza, G0LCU...

1 comment

Barry Walker (author) 8 years, 10 months ago  # | flag

Sorry guys and galsposted the wrong version...

Revision 2 is the correct version. I posted an experimental Arduino version instead, although it would work it would give the wrong final hexdump.

The first line is in comment form as this might work in different shells, not just bash...

Bazza, G0LCU...

Created by Barry Walker on Tue, 29 Jan 2013 (CC0)
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