м с использованием Mono 2.10 работает на Ubuntu 12 x64. Теперь мне нужно знать, как использовать неуправляемый код.

[DllImport("libc.so")]
public static extern int getpid ();

И на следующем этапе у меня есть:

getpid();

и я получаю эту ошибку

$ MONO_LOG_LEVEL="debug" MONO_LOG_MASK="dll" mono libc_test.exe
Mono: DllImport attempting to load: 'libc.so'.
Mono: DllImport loading library:     '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so'.
Mono: DllImport error loading library '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so: cannot open shared     object file: No such file or directory'.
Mono: DllImport loading library:     '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so'.
Mono: DllImport error loading library     '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so: cannot open shared     object file: No such file or directory'.
Mono: DllImport loading location: 'libc.so'.
Mono: DllImport error loading library: '/usr/lib/x86_64-linux-gnu/libc.so: invalid     ELF header'.
Mono: DllImport loading location: 'libc.so'.
Mono: DllImport error loading library: '/usr/lib/x86_64-linux-gnu/libc.so: invalid     ELF header'.
Mono: DllImport loading: 'libc.so'.
Mono: DllImport error loading library '/usr/lib/x86_64-linux-gnu/libc.so: invalid     ELF header'.
Mono: DllImport unable to load library '/usr/lib/x86_64-linux-gnu/libc.so: invalid     ELF header'.
Mono: DllImport attempting to load: 'libc.so'.
Mono: DllImport loading library:     '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so'.
Mono: DllImport error loading library     '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so: cannot open shared     object file: No such file or directory'.
Mono: DllImport loading library:     '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so'.
Mono: DllImport error loading library         '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so: cannot open shared     object file: No such file or directory'.
Mono: DllImport loading location: 'libc.so'.
Mono: DllImport error loading library: '/usr/lib/x86_64-linux-gnu/libc.so: invalid     ELF header'.
Mono: DllImport loading location: 'libc.so'.
Mono: DllImport error loading library: '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.
Mono: DllImport loading: 'libc.so'.
Mono: DllImport error loading library '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.
Mono: DllImport unable to load library '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.
Hello Linux!
Mono: DllImport attempting to load: 'libc.so'.
Mono: DllImport loading library: '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so'.
Mono: DllImport error loading library '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so: cannot open shared     object file: No such file or directory'.
Mono: DllImport loading library: '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so'.
Mono: DllImport error loading library '/home/ibaranov/Documents/MONO/libc_test/libc_test/bin/Debug/libc.so: cannot open shared object file: No such file or directory'.
Mono: DllImport loading location: 'libc.so'.
Mono: DllImport error loading library: '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.
Mono: DllImport loading location: 'libc.so'.
Mono: DllImport error loading library: '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.
Mono: DllImport loading: 'libc.so'.
Mono: DllImport error loading library '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.
Mono: DllImport unable to load library '/usr/lib/x86_64-linux-gnu/libc.so: invalid ELF header'.

Unhandled Exception: System.DllNotFoundException: libc.so
  at (wrapper managed-to-native) libc_test.LibC:getpid ()
  at libc_test.MainClass.Main (System.String[] args) [0x00000] in :0 
[ERROR] FATAL UNHANDLED EXCEPTION: System.DllNotFoundException: libc.so
  at (wrapper managed-to-native) libc_test.LibC:getpid ()
  at libc_test.MainClass.Main (System.String[] args) [0x00000] in :0 

Я давно пытаюсь решить эту проблему, но ничто из того, что я пробовал, не помогает мне. Я использую:

 dlopen("libc.so", RTLD_NOW);

Может мне нужен libc.so скомпилированный для x64?