CODEWITHSUNDEEP
c++clinuxenvironment-variablesshared-libraries
CDT
CDT

Reputation: 10661

Linux - SO file not found

I have a program which requires liblog4cpp installed to run.

Now, I want the program to run on another machine without liblog4cpp. So I just find the log4cpp.so and move it to the same directory of my program. But at running error reported:

error while loading shared libraries: liblog4cpp.so.4: cannot open shared object file: No such file or directory

Am I doing it right? How can I tell the program to find the SO file just beside it?

Upvotes: 8

Views: 24460

Answers (6)

user2485710
user2485710

Reputation: 9801

assuming that the path where the .so file/s is available is /path you can also avoid to export an environment variable and just use 

LD_LIBRARY_PATH=/path ./myProgram

beware the fact that if you do:

export LD_LIBRARY_PATH=/path

you are resetting LD_LIBRARY_PATH to a single value /path and losing anything you added before to this environment variable. If you want to add a value without losing the previous ones

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path

Upvotes: 7

dexterous
dexterous

Reputation: 6526

In the rc script from where you are launching your program, you should set the LD_LIBRARAY_PATH before launching the application. Remember, the .so are the shared libraries, it is required at the run time to link. Thus, it should be available in the standard path like /usr/lib before launching. In case it is not copied in the standard path like /usr/lib then specify the path by using the following.

export LD_LIBRARY_PATH=<new_path_of_so>:$(LD_LIBRARY_PATH)

Ideally, I would have placed this .so in the standard path like /usr/lib. If it is installed in the standard path, then there is no need to set the above path. Remember, to make your program better, put the new path in ldconfig.conf.

You can debug such errors by using the following.

$strace <binary_name>

to know the so dependencies

$ldd <binary_name>

For further, check the below link.

http://www.tune2wizard.com/sharedobject-crash/

Upvotes: 6

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

After adding shared objects (or shared libraries lib*.so*, or such symbolic links) to system directories like /usr/lib or /lib known to the dynamic linker ld-linux.so(8) (or ld.so) you need to run ldconfig(8)

You could also add them to /usr/local/lib/ but then be sure that /etc/ld.so.conf (or some file /etc/ld.so.conf.d/*.conf) .mentions that directory (and run ldconfig after changing it)

Upvotes: 2

NlightNFotis
NlightNFotis

Reputation: 9803

In addition to what others are suggesting, consider adding the file to the dynamic linker's cache. You can do it like this:

ldconfig -l /path/to/lib/liblog4.so.4

To add it to the loader's cache use the following command: ldconfig

Then in order to verify that it was correctly added, run this:

ldconfig -v | grep liblog

Upvotes: 11

Tom
Tom

Reputation: 2389

Check your LD_LIBRARY_PATH environment variable... One of the directories on the path should point to the location of your log4cpp.so file; also the linux command ldd is handy for determining which shared object libraries are being used in your executable. The syntax is ldd <executable>.

Upvotes: 9

Pete B.
Pete B.

Reputation: 3286

export LD_LIBRARY_PATH to the path of the library. This env variable works much like the PATH variable. It can contain multiple paths separated by :.

Upvotes: 4

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