OSError: libX11.so: cannot open shared object

[Antonio Galli]

My system is an Ubuntu 11.04 64bit

Traceback (most recent call last):
  File "/usr/bin/complexshutdown.py", line 98, in <module>
    xlib = ctypes.cdll.LoadLibrary('libX11.so')
  File "/usr/lib/python2.7/ctypes/__init__.py", line 431, in LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python2.7/ctypes/__init__.py", line 353, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: libX11.so: cannot open shared object file: No such file or directory

I tried

 sudo ln -s /usr/lib32/libX11.so.6 /usr/lib/libX11.so

and I had

Traceback (most recent call last):
  File "/usr/bin/complexshutdown.py", line 98, in <module>
    xlib = ctypes.cdll.LoadLibrary('libX11.so')
  File "/usr/lib/python2.7/ctypes/__init__.py", line 431, in LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python2.7/ctypes/__init__.py", line 353, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: libX11.so: wrong ELF class: ELFCLASS32

[Ralph Corderoy (ralph-inputplus)]

Opening that library in Python works on this 10.10 64-bit Ubuntu. There
was already a symbolic link in place but it points to somewhere
different to the one created above.

    $ strace -e open python -c '
            import ctypes; print ctypes.cdll.LoadLibrary("libX11.so")
        ' 2>&1 |
    > grep X11
    open("/usr/lib/libX11.so", O_RDONLY) = 3
    <CDLL 'libX11.so', handle 1042fb0 at 7f8d35b4ae50>
    $ ls -l /usr/lib/libX11.so
    lrwxrwxrwx 1 root root 15 2011-10-30 00:43 /usr/lib/libX11.so -> libX11.so.6.3.0
    $ ls -l /usr/lib/libX11.so.6.3.0
    -rw-r--r-- 1 root root 1269216 2010-05-13 17:06 /usr/lib/libX11.so.6.3.0
    $