Python executable not finding libpython shared library

Question

I am installing Python 2 7 on CentOS 5  I built and installed Python as follows    configure --enable-shared --prefix  usr local make make install   When I try to run  usr local bin python  I get this error message   usr local bin python  error while loading shared libraries  libpython2 7 so 1 0  cannot open shared object file  No such file or directory   When I run ldd on  usr local bin python  I get  ldd  usr local bin python     libpython2 7 so 1 0   gt  not found     libpthread so 0   gt   lib64 libpthread so 0  0x00000030e9a00000      libdl so 2   gt   lib64 libdl so 2  0x00000030e9200000      libutil so 1   gt   lib64 libutil so 1  0x00000030fa200000      libm so 6   gt   lib64 libm so 6  0x00000030e9600000      libc so 6   gt   lib64 libc so 6  0x00000030e8e00000       lib64 ld-linux-x86-64 so 2  0x00000030e8a00000    How do I tell Python where to find libpython

User · Answer

This worked for me       sudo apt-get install python2 7-dev

User · Answer

I installed using the command     configure --prefix  usr                     --enable-shared                   --with-system-expat               --with-system-ffi                 --enable-unicode ucs4  amp  amp   make   Now  as the root user   make install  amp  amp  chmod -v 755  usr lib libpython2 7 so 1 0   Then I tried to execute python and got the error       usr local bin python  error while loading shared libraries  libpython2 7 so 1 0  cannot open shared object file  No such file or directory   Then  I logged out from root user and again tried to execute the Python and it worked successfully

User · Answer

Putting on my gravedigger hat     The best way I ve found to address this is at compile time   Since you re the one setting prefix anyway might as well tell the executable explicitly where to find its shared libraries   Unlike OpenSSL and other software packages  Python doesn t give you nice configure directives to handle alternate library paths  not everyone is root you know      In the simplest case all you need is the following     configure --enable-shared               --prefix  usr local               LDFLAGS  -Wl --rpath  usr local lib    Or if you prefer the non-linux version     configure --enable-shared               --prefix  usr local               LDFLAGS  -R usr local lib    The  rpath  flag tells python it has runtime libraries it needs in that particular path   You can take this idea further to handle dependencies installed to a different location than the standard system locations   For example  on my systems since I don t have root access and need to make almost completely self-contained Python installs  my configure line looks like this     configure --enable-shared               --with-system-ffi               --with-system-expat               --enable-unicode ucs4               --prefix  apps python-  PYTHON VERSION                LDFLAGS  -L apps python-  PYTHON VERSION  extlib lib -Wl --rpath  apps python-  PYTHON VERSION  lib -Wl --rpath  apps python-  PYTHON VERSION  extlib lib                CPPFLAGS  -I apps python-  PYTHON VERSION  extlib include    In this case I am compiling the libraries that python uses  like ffi  readline  etc  into an extlib directory within the python directory tree itself   This way I can tar the python-  PYTHON VERSION  directory and land it anywhere and it will  work   provided you don t run into libc or libm conflicts    This also helps when trying to run multiple versions of Python on the same box  as you don t need to keep changing your LD LIBRARY PATH or worry about picking up the wrong version of the Python library   Edit   Forgot to mention  the compile will complain if you don t set the PYTHONPATH environment variable to what you use as your prefix and fail to compile some modules  e g   to extend the above example  set the PYTHONPATH to the prefix used in the above example with export PYTHONPATH  apps python-  PYTHON VERSION

User · Answer

just install python-lib   python27-lib   It will install libpython2 7 so1 0  We don t require to manually set anything

User · Answer

All it needs is the installation of libpython  3 or 2  dev files installation

User · Answer

I had the same problem and I solved it this way   If you know where libpython resides at  I supposed it would be  usr local lib libpython2 7 so 1 0 in your case  you can just create a symbolic link to it   sudo ln -s  usr local lib libpython2 7 so 1 0  usr lib libpython2 7 so 1 0   Then try running ldd again and see if it worked

User · Answer

On Solaris 11  Use LD LIBRARY PATH 64 to resolve symlink to python libs   In my case for python3 6 LD LIBRARY PATH didn t work but LD LIBRARY PATH 64 did   Hope this helps  Regards

User · Answer

Try the following   LD LIBRARY PATH  usr local lib  usr local bin python   Replace  usr local lib with the folder where you have installed libpython2 7 so 1 0 if it is not in  usr local lib   If this works and you want to make the changes permanent  you have two options    Add export LD LIBRARY PATH  usr local lib to your  profile in your home directory  this works only if you are using a shell which loads this file when a new shell instance is started   This setting will affect your user only  Add  usr local lib to  etc ld so conf and run ldconfig  This is a system-wide setting of course

User · Answer

This answer would be helpful to those who have limited auth access on the server  I had a similar problem for python3 5 in HostGator s shared hosting  Python3 5 had to be enabled every single damn time after login  Here are my 10 steps for resolution   Enable the python through scl script python enable 3 5 or scl enable rh-python35 bash   Verify that it s enabled by executing python3 5 --version  This should give you your python version   Execute which python3 5 to get its path  In my case  it was  opt rh rh-python35 root usr bin python3 5  You can use this path get the version again  just to verify that this path is working for you    Awesome  now please exit out of current shell by scl   Now  lets get the version again through this complete python3 5 path  opt rh rh-python35 root usr bin python3 5 --version  It won t give you the version but an error  In my case  it was    opt rh rh-python35 root usr bin python3 5  error while loading shared libraries  libpython3 5m so rh-python35-1 0  cannot open shared object file  No such file or directory   As mentioned in Tamas  answer  we gotta find that so file  locate doesn t work in shared hosting and you can t install that too  Use the following command to find where that file is located    find  opt rh rh-python35 -name  quot libpython3 5m so rh-python35-1 0 quot    Above command would print the complete path  second line  of the file once located  In my case  output was  find    opt rh rh-python35 root root   Permission denied  opt rh rh-python35 root usr lib64 libpython3 5m so rh-python35-1 0   Here is the complete command for the python3 5 to work in such shared hosting which would give the version   LD LIBRARY PATH  opt rh rh-python35 root usr lib64  opt rh rh-python35 root usr bin python3 5 --version   Finally  for shorthand  append the following alias in your    bashrc  alias python351  LD LIBRARY PATH  opt rh rh-python35 root usr lib64  opt rh rh-python35 root usr bin python3 5    For verification  reload the  bashrc by source    bashrc and execute python351 --version   Well  there you go  now whenever you login again  you have got python351 to welcome you  This is not just limited to python3 5  but can be helpful in case of other scl installed softwares

User · Answer

I installed Python 3 5 by Software Collections on CentOS 7 minimal  It all worked fine on its own  but I saw the shared library error mentioned in this question when I tried running a simple CGI script   tail  var log httpd error log AH01215   opt rh rh-python35 root usr bin python  error while loading shared libraries  libpython3 5m so rh-python35-1 0  cannot open shared object file  No such file or directory   I wanted a systemwide permanent solution that works for all users  so that excluded adding export statements to  profile or  bashrc files  There is a one-line solution  based on the Red Hat solutions page  Thanks for the comment that points it out   echo  source scl source enable rh-python35    sudo tee --append  etc profile d python35 sh   After a restart  it s all good on the shell  but sometimes my web server still complains  There s another approach that always worked for both the shell and the server  and is more generic  I saw the solution here and then realized it s actually mentioned in one of the answers here as well  Anyway  on CentOS 7  these are the steps    vim  etc ld so conf   Which on my machine just had   include ld so conf d   conf   So I created a new file   vim  etc ld so conf d rh-python35 conf   And added    opt rh rh-python35 root usr lib64    And to manually rebuild the cache   sudo ldconfig   That s it  scripts work fine   This was a temporary solution  which didn t work across reboots   sudo ldconfig  opt rh rh-python35 root usr lib64  -v   The -v  verbose  option was just to see what was going on  I saw that it did       opt rh rh-python35 root usr lib64          libpython3 so rh-python35 -  libpython3 so rh-python35         libpython3 5m so rh-python35-1 0 -  libpython3 5m so rh-python35-1 0  This particular error went away  Incidentally  I had to chown the user to apache to get rid of a permission error after that   Note that I used find to locate the directory for the library  You could also do   sudo yum install mlocate sudo updatedb locate libpython3 5m so rh-python35-1 0   Which on my VM returns    opt rh rh-python35 root usr lib64 libpython3 5m so rh-python35-1 0   Which is the path I need to give to ldconfig  as shown above

[python] Python executable not finding libpython shared library

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