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/lib/i386-linux-gnu/libc.so.6,/lib/x86_64-linux-gnu/libc.so.6和/usr/lib/x86_64-linux-gnu/libc.so之间的区别是什么?

更新时间:2023-02-02 21:14:09

  

/lib/i386-linux-gnu/libc.so.6

这是为32位版本的库。

  

/lib/x86_64-linux-gnu/libc.so.6

这是64位版本的库。

这两种通常的符号链接到实际的库文件,这通常会根据glibc的版本号命名,例如 libc-2.15.so

  

/usr/lib/x86_64-linux-gnu/libc.so

这不是一个库,但是一链接脚本文件,它是指在上述符号链接

为什么我们需要所有这些:

首先,不管安装的libc版本,链接器将随时搜索 libc.so ,因为编译器驱动程序会一直传递到连接器的 -lc 选项。该名称的libc 保持不变,并表示到最新版本的库。

创建符号链接 libc.so.6的命名后的的soname 的图书馆,这,或多或少对应于ABI版本图书馆。该可执行文件,实际上链接的反对 libc.so 包含关于 libc.so.6的运行时依赖。

如果我们想象一个严重ABI不相容的libc被释放的一天,它的soname可以被命名为 libc.so.7 ,例如这个版本coukld共存与旧 libc.so.6的的版本,从而可执行文件已对链接一个或另一个可以在同一个系统***存,

最后,名称 libc-2.15.so 指的是libc的版本中,当你安装一个新的libc包,名称将改为 libc-2.16.so 。只要它是二进制数,previous版本兼容,在 libc.so.6的的链接将保持这样的命名方式和现有的可执行文件将继续工作。

I installed Matlab in my Linux Mint 14 Nadia (a uname -a shows: Linux Ideapad-Z570 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:31:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux) and when calling it from the command line I would get a: "/lib64/libc.so not found".

I followed the help on mathworks by making a link in /lib64 as:

ln -s /lib/x86_64-linux-gnu/libc.so.6 .

That solved the issue.

Now, if I do a locate of this library I get:

locate "libc.so"
/lib/i386-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libc.so.6
/usr/lib/x86_64-linux-gnu/libc.so

I will be compiling with gcc in this computer and I would like to have full 64bit compilations. What does exactly mean to have all these different libc.so libraries? which one will the gnu compiler be using? do I need to do anything different with gcc to compile for 64 bits?

I would also love to optimize as much as I can for my new i7 core!!!

/lib/i386-linux-gnu/libc.so.6

This is is 32-bit version of the library.

/lib/x86_64-linux-gnu/libc.so.6

This is the 64-bit version of the library.

Both are usually symbolic links to the actual library file, which will usually be named according to the glibc release number, for example libc-2.15.so

/usr/lib/x86_64-linux-gnu/libc.so

This is not a library, but a linker script file, which refers to the above symlinks.

Why do we need all these:

First, regardless of libc version installed, the linker will always search for libc.so, because the compiler driver will always pass to the linker the -lc options. The name libc stays the same and denotes to most recent version of the library.

The symlinks libc.so.6 are named after the soname of the library, which, more or less corresponds to the ABI version of the library. The executables, linked against libc.so in fact contain runtime dependencies on libc.so.6.

If we imagine the someday a grossly ABI incompatible libc is released, it's soname could be named libc.so.7, for example and this version coukld coexists with the older libc.so.6 version, thus executables linked against one or the other can coexist in the same system,

And finally, the name libc-2.15.so refers to the libc release, when you install a new libc package, the name will change to libc-2.16.so. Provided that it is binary compatible with the previous release, the libc.so.6 link will stay named that way and the existing executables will continue to work.