gdb 打印内存 x

GNU gdb (Ubuntu 7.11.-0ubuntu1~16.04) 7.11.
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(gdb) help x
Examine memory: x/FMT ADDRESS.
ADDRESS is an expression for the memory address to examine.
FMT is a repeat count followed by a format letter and a size letter.
Format letters are o(octal), x(hex), d(decimal), u(unsigned decimal),
  t(binary), f(float), a(address), i(instruction), c(char), s(string)
  and z(hex, zero padded on the left).
Size letters are b(byte), h(halfword), w(word), g(giant,  bytes).
The specified number of objects of the specified size are printed
according to the format.

Defaults for format and size letters are those previously used.
Default count is .  Default address is following last thing printed
with this command or "print".
(gdb) 

x

help x

打印一段内存：

x /12xb addr