GDB

== Structure ==
You can see what is going on "inside" another program while it executes
or what other program was doing at the moment it crashed.
gdb can do four main kinds of things to achive the goals mentioned above:
Start your program, specifying anything that might affect its behavior.
Make your program stop on specified conditions.
Examine what has happened, when your program has stopped.
Change things in your program, so you can experiment with correcting the effects of one bug and go on to learn about another.

== Understand ==
Start your program, specifying anything that might affect its behavior.
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Invokes gdb
Running under gdb

Make your program stop on specified conditions.
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Stoping and continuing

Examine what has happened, when your program has stopped.
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Examin stack, source file, data, symbols table.

Altering Execution
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###Parctice
gdb 调试 core.


print {}