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<title>What does "dead beef" mean?</title>
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<h1><a href="https://stackoverflow.com/questions/2907262/what-does-dead-beef-mean" style="color: #70a1c2;">What does "dead beef" mean?</a></h1>
<p>Asked 13 years, 8 months ago Modified 8 months ago Viewed 161k times</p>
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133 upvotes<br>
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What does the word "dead beef" mean? I read it from a interview question.
It has something to do with ipv6.
I figured it could be a random hex number used for examples, like "The quick brown fox jumps over the lazy dog".
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Is my understanding correct? Or it has more significant meaning?
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<h2>8 Answers</h2>
144 upvotes
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<a href="http://en.wikipedia.org/wiki/Hexspeak" style="color: #70a1c2;">http://en.wikipedia.org/wiki/Hexspeak</a><br>
<a href="http://www.urbandictionary.com/define.php?term=dead%3Abeef" style="color: #70a1c2;">http://www.urbandictionary.com/define.php?term=dead%3Abeef</a><br>
"Dead beef" is a very popular sentence in programming, because it is built only from letters a-f, which are used in hexadecimal notation.
Colons in the beginning and in the middle of the sentence make this sentence a (theoretically) valid IPv6 address.
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<p style="font-size: 12px">edited Feb 15, 2018 at 14:12 NikxDa
<br>answered May 25, 2010 at 18:10 Dustin Laine</p>
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94 upvotes<br>
The value of 0xDEADBEEF has three practical benefits, mostly for older systems.
Old assembler/C hacks, like me, would use it to fill unallocated memory to coax out memory issues.
Also, it's a pun of the slang term "dead meat". The programmer is dead meat if DEADBEEF winds up in his pointers.
I congratulate the guy who first thought of using the value DEADBEEF. It's clever in many ways. <br>
As for practical reasons, firstly, it's more noticeable in a hex memory dump because it actually spells words as opposed to random hex values.<br>
Secondly, if the value winds up in a pointer, it's more likely to induce a memory out-of-range fault.
An address of DEADBEEF was out of the address range of systems (we're talking last century systems now) regardless of the system's endian.<br>
Thirdly, it is more likely to induce a fault on systems that require even boundary pointer values for accessing 16/32/64-bit data.
The value is more likely to fault because both of the 16 bit values (DEAD, BEEF) are odd.
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<p style="font-size: 12px">edited Feb 9, 2016 at 11:21
<br>answered May 25, 2010 at 20:25 BSalita</p>
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59 upvotes<br>
It's a made up expression using only the letters A-F, often used when a recognisable hexadecimal number is required.
Some systems use it for various purposes such as showing memory which has been freed and should not be referenced again.
In a debugger this value showing up could be a sign that you have made an error. <nobr>From <a href="https://en.wikipedia.org/wiki/Hexspeak" style="color: #70a1c2;">Wikipedia</a>:</nobr>
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0xDEADBEEF ("dead beef") is used by IBM RS/6000 systems, Mac OS on 32-bit PowerPC processors and the Commodore Amiga as a magic debug value.
On Sun Microsystems' Solaris, it marks freed kernel memory. On OpenVMS running on Alpha processors, DEAD_BEEF can be seen by pressing CTRL-T.
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The number 0xDEADBEEF is equal to the less recognisable decimal number 3735928559 (unsigned) or -559038737 (signed).
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<p style="font-size: 12px">answered May 25, 2010 at 18:11 Mark Byers</p>
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26 upvotes<br>
Since IPv6-Adresses are written in Hex-notation you can use "Hexspeak" (numbers 0-9 and letters a-f) in Adresses.
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There are a number of words you can use as valid adresses to better momorize them.
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If you ping6 www.facebook.com -n you will get something like "2a03:2880:f01c:601:face:b00c:0:1".
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Here are some examples:
<ul>
<li>:affe:: (Affe - German for Monkey - seen at a vlan for management board)</li>
<li>:1bad:babe:: (one bad babe - seen at a smtp-honeypot)</li>
<li>:badc:ab1e:: (bad cable - seen as subnet for a unsecure vlan)</li>
<li>:da7a:: (Data - seen for fileservers)</li>
<li>:d1a1:: (Dial - seen for VPN Dial-In)</li>
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edited Feb 15, 2018 at 13:25
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answered Jul 11, 2014 at 16:56 Martin Seitl</p>
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15 upvotes<br>
It is also used for debugging purposes. <br>
Here is a handy list of some of these values: <br>
<a href="http://en.wikipedia.org/wiki/Magic_number_%28programming%29#Magic_debug_values" style="color: #70a1c2;">http://en.wikipedia.org/wiki/Magic_number_%28programming%29#Magic_debug_values</a>
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<p style="font-size: 12px">answered May 25, 2010 at 18:10 Scott</p>
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4 upvotes<br>
People normally use it to indicate dummy values. I think that it primarily was used before the idea of NULL pointers. <br>
<p style="font-size: 12px">answered May 25, 2010 at 18:09 Puppy</p>
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3 upvotes<br>
It's a magic number used in various places because it also happens to be readable in English, making it stand out.
There's a partial list on <a href="http://en.wikipedia.org/wiki/Magic_number_(programming)" style="color: #70a1c2;">Wikipedia</a>.
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<p style="font-size: 12px">answered May 25, 2010 at 18:11 dsolimano</p>
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2 upvotes<br>
It was used as a pattern to store in memory as a series of hex bytes (0xde, 0xad, 0xbe, 0xef).
You could see if memory was corrupted because of hardware failure, buffer overruns, etc.
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<p style="font-size: 12px">answered May 25, 2010 at 18:11 Larry</p>
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