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In shell, how can I read the bytes of a binary file I have, and print the output as hexadecimal numbers?

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8 Answers 8

78

Use hexdump(1)

$ hexdump -x /usr/bin/hexdump 
0000000    feca    beba    0000    0300    0001    0700    0080    0300
0000010    0000    0010    0000    5080    0000    0c00    0000    0700
0000020    0000    0300    0000    00a0    0000    b06f    0000    0c00
0000030    0000    1200    0000    0a00    0100    0010    0000    107c
0000040    0000    0c00    0000    0000    0000    0000    0000    0000
0000050    0000    0000    0000    0000    0000    0000    0000    0000

...

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  • 10
    Also check out od. There is also a vi-style hex editor called hexer.
    – LawrenceC
    Apr 7, 2011 at 14:47
  • 14
    I like the output of "hexdump -C file" better. xxd is also a nice tool.
    – Kambus
    Apr 7, 2011 at 17:09
  • 1
    show in bash hexa format hexdump -e '"\\\x" /1 "%02x"' filename Nov 20, 2014 at 16:10
  • 4
    For information, the first column is the hexadecimal offset of the bytes, the rest of the line is 8 sets of two-byte displays, i.e. 16 bytes, which is why the second line starts with an offset of 10, which is 16 in hexadecimal. The two-byte representation depends on the endianness of the system. Type man hexdump for the full details.
    – emonigma
    Dec 7, 2018 at 13:23
  • my above trick is bad, hexdump will output '*\n' for any repeating bytes. I am using this instead: ... |od -A n -t x1 |tr -d ' \n' Aug 20, 2023 at 23:50
46

Another option is od:

od -t x1 FILE

sample output:

$ printf '0123456789abcdef0123456789abcdef\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f' | od -t x1
0000000 30 31 32 33 34 35 36 37 38 39 61 62 63 64 65 66
*
0000040 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
0000060

or

od -x FILE

sample output:

0000000 3130 3332 3534 3736 3938 6261 6463 6665
*
0000040 0100 0302 0504 0706 0908 0b0a 0d0c 0f0e
0000060

od has many options for finetuning.

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  • 12
    Most people would find od -t x1 as preferred format I guess.
    – alex
    Apr 7, 2011 at 16:43
  • For the line od -t test I got od: invalid character 't' in type string 'test' Apr 11, 2011 at 13:52
  • 1
    It worked with --t Apr 11, 2011 at 13:53
  • @Tom: Maybe a different Unix/Linux flavor? My od is: od --version od (GNU coreutils) 7.4 Apr 11, 2011 at 15:01
  • If it can help somebody else, I wanted to have the last 4 bytes in hex of a binary file. Here is what I did that works. od -A n -t x1 -w1 -v myFile.bin | tail -n 4 | sed 's/ //g' | paste -sd ''
    – mgouin
    Feb 17, 2022 at 18:53
29

While we're on od and hexdump, two more similar tools:

  • hd (from bsdmainutils)
  • xxd (part of Vim)

Sample output:

$ hd /usr/bin/od | head
00000000  7f 45 4c 46 01 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
00000010  02 00 03 00 01 00 00 00  20 8e 04 08 34 00 00 00  |........ ...4...|
00000020  a4 a2 00 00 00 00 00 00  34 00 20 00 08 00 28 00  |........4. ...(.|
00000030  1b 00 1a 00 06 00 00 00  34 00 00 00 34 80 04 08  |........4...4...|
00000040  34 80 04 08 00 01 00 00  00 01 00 00 05 00 00 00  |4...............|
00000050  04 00 00 00 03 00 00 00  34 01 00 00 34 81 04 08  |........4...4...|
00000060  34 81 04 08 13 00 00 00  13 00 00 00 04 00 00 00  |4...............|
00000070  01 00 00 00 01 00 00 00  00 00 00 00 00 80 04 08  |................|
00000080  00 80 04 08 c4 9d 00 00  c4 9d 00 00 05 00 00 00  |................|
00000090  00 10 00 00 01 00 00 00  00 a0 00 00 00 20 05 08  |............. ..|

$ xxd /usr/bin/od | head
0000000: 7f45 4c46 0101 0100 0000 0000 0000 0000  .ELF............
0000010: 0200 0300 0100 0000 208e 0408 3400 0000  ........ ...4...
0000020: a4a2 0000 0000 0000 3400 2000 0800 2800  ........4. ...(.
0000030: 1b00 1a00 0600 0000 3400 0000 3480 0408  ........4...4...
0000040: 3480 0408 0001 0000 0001 0000 0500 0000  4...............
0000050: 0400 0000 0300 0000 3401 0000 3481 0408  ........4...4...
0000060: 3481 0408 1300 0000 1300 0000 0400 0000  4...............
0000070: 0100 0000 0100 0000 0000 0000 0080 0408  ................
0000080: 0080 0408 c49d 0000 c49d 0000 0500 0000  ................
0000090: 0010 0000 0100 0000 00a0 0000 0020 0508  ............. ..

Or, if you want to read the bytes one at a time and print them in your own format, try something like:

while read -n 1 byte; do
    ord=$(printf "%b" "${byte:-\000}" |
          od -t x1 |
          { read offset hex; echo $hex; })
    echo "$ord"
done </usr/bin/od

Sample output:

7f
45
4c
46
01
01
01
00
00
00
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  • 4
    unlike the other, xxd is also able to revert the modification. With that, it is possible to alter a binary file with shell.
    – Offirmo
    Jun 11, 2012 at 16:31
  • 2
    Your while loop doesn't work for backslash and newline characters (and in bash (as opposed to ksh93) for blank characters), nor will it work properly in utf8 locales for bytes with the 8th bit set. Also, you don't need "od" there, you can use printf '%02x\n' "'$byte" Oct 15, 2012 at 20:13
  • Note: offset is merely a sort of "dummy variable" here; it has no practical use. It is just used as a placeholder to get to hex. This is what sometimes affects readability in a negative way with read: variables coming out of the blue. Dec 2, 2014 at 0:01
  • Perhaps. But in this case, the scope of $offset is limited by the subshell, so I don't see it as a problem.
    – Mikel
    Dec 2, 2014 at 3:44
  • This doesn't work because doesn't print 0a only 0d
    – Smeterlink
    Aug 21, 2022 at 17:45
8

My two cents:

tail -f streamfile | hexdump -C

I like this because you are tailing a currently buffering file while being able to see the hexdump live. Don't forget that EVERYTHING in Unix is a file and we can easily chain commands like tail and hexdump to solve a wide variety of problems.

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  • tested with for((i=0;i<100;i++));do echo $i >>tst2.bin;sleep 1;done& it works well for monitoring thx :) Nov 20, 2014 at 15:56
5
mc 

The midnight commander is another option. I don't know whether it is available for all unix flavors. You might need to download it first.
F3 F4 to view in internal editor/ in hex mode.

3

I use od with c and x1, when I need to search for text inside the binary file:

$ echo "Some text..." | od -t c -t x1
0000000   S   o   m   e       t   e   x   t   .   .   .  \n
         53  6f  6d  65  20  74  65  78  74  2e  2e  2e  0a
0000015
1

If the data you're viewing is mostly text with occasional binary, you might find the -v option to cat(1) convenient:

$ printf 'here is\x00\x01some text\x15\x16with the odd bit\x80\x81of binary mixed in' | cat -v
here is^@^Asome text^U^Vwith the odd bitM-^@M-^Aof binary mixed in

Non-printing bytes ≤ 0x7f are displayed with control-character notation. Bytes ≥ 0x80 are prefixed by M-.

This isn't reversible since M- itself doesn't appear to be escaped. Nonetheless, it can be easier to read than the full canonical hex dump format given by hd(1) and other tools.

1

Get raw hex byte string without any formatting

This form can also be useful when you want to convert data rather than view it manually:

od -An -v -tx1 | tr -d ' \n'

Example:

printf '0123456789abcdef0123456789abcdef\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f' | od -An -v -tx1 | tr -d ' \n'

Output:

3031323334353637383961626364656630313233343536373839616263646566000102030405060708090a0b0c0d0e0f

So no spaces or newlines, just the hex.

Tested on Ubuntu 23.04.

Related: https://stackoverflow.com/questions/2003803/show-hexadecimal-numbers-of-a-file

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