How do I compare binary files in Linux?

I need to compare two binary files and get the output in the form:

<fileoffset-hex> <file1-byte-hex> <file2-byte-hex>

for every different byte. So if file1.bin is

  00 90 00 11

in binary form and file2.bin is

  00 91 00 10

I want to get something like

  00000001 90 91
  00000003 11 10

Is there a way to do this in Linux? I know about cmp -l but it uses a decimal system for offsets and octal for bytes which I would like to avoid.

Solution 1:

This will print the offset and bytes in hex:

cmp -l file1.bin file2.bin | gawk '{printf "%08X %02X %02X\n", $1, strtonum(0$2), strtonum(0$3)}'

Or do $1-1 to have the first printed offset start at 0.

cmp -l file1.bin file2.bin | gawk '{printf "%08X %02X %02X\n", $1-1, strtonum(0$2), strtonum(0$3)}'

Unfortunately, strtonum() is specific to GAWK, so for other versions of awk—e.g., mawk—you will need to use an octal-to-decimal conversion function. For example,

cmp -l file1.bin file2.bin | mawk 'function oct2dec(oct,     dec) {for (i = 1; i <= length(oct); i++) {dec *= 8; dec += substr(oct, i, 1)}; return dec} {printf "%08X %02X %02X\n", $1, oct2dec($2), oct2dec($3)}'

Broken out for readability:

cmp -l file1.bin file2.bin |
    mawk 'function oct2dec(oct,    dec) {
              for (i = 1; i <= length(oct); i++) {
                  dec *= 8;
                  dec += substr(oct, i, 1)
              };
              return dec
          }
          {
              printf "%08X %02X %02X\n", $1, oct2dec($2), oct2dec($3)
          }'

Solution 2:

As ~quack pointed out:

 % xxd b1 > b1.hex
 % xxd b2 > b2.hex

And then

 % diff b1.hex b2.hex

or

 % vimdiff b1.hex b2.hex

Solution 3:

diff + xxd

Try diff in the following combination of zsh/bash process substitution:

diff -y <(xxd foo1.bin) <(xxd foo2.bin)

Where:

• -y shows you differences side-by-side (optional).
• xxd is CLI tool to create a hexdump output of the binary file.
• Add -W200 to diff for wider output (of 200 characters per line).
• For colors, use colordiff as shown below.

colordiff + xxd

If you've colordiff, it can colorize diff output, e.g.:

colordiff -y <(xxd foo1.bin) <(xxd foo2.bin)

^{Otherwise install via: sudo apt-get install colordiff.}

Sample output:

vimdiff + xxd

You can also use vimdiff, e.g.

vimdiff <(xxd foo1.bin) <(xxd foo2.bin)

Hints:

• if files are too big, add limit (e.g. -l1000) for each xxd