Hexdumping - ETOOBUSY

TL;DR

There’s hexdump. Then there’s xxd (and Data::HexDump::XXD).

I read about manwar’s journey to hexdumping and I discovered that a plain call to hexdump might not always give back the same result. At least on a Linux box and on a Mac:

# In a Linux box
$ printf ABCD | hexdump
0000000 4241 4443                              
0000004

# In Mac OS X
$ printf ABCD | hexdump
0000000 41 42 43 44
0000004

I know, I know… by Linux I mean my Debian Linux installation in a virtual machine that runs over an Intel-based x86_6 chip.

I initially thought that I was looking at two different implementations, which can happen frequently in this kind of comparisons because Mac OS X is based on BSD. Then I called man hexdump in the Linux box:

HEXDUMP(1)            BSD General Commands Manual            HEXDUMP(1)

NAME
     hexdump, hd — ASCII, decimal, hexadecimal, octal dump
...

OK, that was not the explanation for the difference. I guess they are basically compiled with different defaults, as explained inside their respective man pages:

########################################################################
# Linux man page

-x  Two-byte hexadecimal display.  Display the input offset in
    hexadecimal, followed by eight, space separated, four column,
    zero-filled, two-byte quantities of input data, in hexadecimal,
    per line.

...

If no format strings are specified, the default display is equivalent
to specifying the -x option.


########################################################################
# Mac OS X man page

If no format strings are specified, the default display is a one-byte
hexadecimal display.

As I read through the options list, -C would have probably helped manwar speed up the investigation:

-C  Canonical hex+ASCII display.  Display the input offset in
    hexadecimal, followed by sixteen space-separated, two column,
    hexadecimal bytes, followed by the same sixteen bytes in %_p format
    enclosed in ``|'' characters.

Let’s test it in the two platforms:

# Linux
$ printf ABCD | hexdump -C
00000000  41 42 43 44                                       |ABCD|
00000004

# Mac OS X
$ printf ABCD | hexdump -C
00000000  41 42 43 44                                       |ABCD|
00000004

Anyway, I prefer xxd to do the hex dumping:

$ printf ABCD | xxd
00000000: 4142 4344                                ABCD

I like it so much that I already wrote about it in Data::HexDump::XXD!

Stay safe folks!

ETOOBUSY 🚀 minimal blogging for the impatient