为什么有些可执行文件没有 main 函数？
我“objdump -d”一个可执行文件，例如/bin/ls，我发现汇编代码中没有任何main函数。为什么？
I "objdump -d" an executable, e.g, /bin/ls, and I found there's not any main function in the assembly code. Why?
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您可能会在大多数尚未删除的可执行文件中找到“main()”：
http: //linux.die.net/man/1/strip
如果运行以下命令，您可能还会看到类似的内容：
You'd probably find a "main()" in most executables that haven't been stripped:
http://linux.die.net/man/1/strip
You'd probably also see something like this if you ran the following:
有几种可能的解释：
main并不意味着世界需要它。main函数可能已被编译器内联或删除。操作系统只是调用一个入口点；它并不关心这是否实际上是一个名为main的函数的开始。objdump）Objdump可能不会公开程序中所有可能的符号；鉴于您将其指向链接的可执行文件而不是目标文件，因此 objdump 并没有真正的合同来告诉您可执行文件中的每个可能的函数；只是那些可能被外部调用的。符号信息只是助记符；处理器根本不考虑这些事情。
There are several possible explanations:
maindoesn't mean the world requires one.mainfunction may have been inlined or eliminated by the compiler in general. The operating system just calls an entry point; it doesn't care if that's actually the start of a function calledmain.objdump)Objdumpmight not expose all possible symbols in a program; given that you're pointing it at linked executable and not object files, there's not really a contract for objdump to tell you every possible function in the executable; just those which might be called externally.Symbolic information are only mnemonics; the processor isn't looking at these things at all.