Linux: Set OR Change The Library Path

I‘ve compile and installed a library at /usr/local/lib/libapp2.so -> libapp2.so.1.4.3. How do I set the Library path under Linux operating systems?

You need to use ldconfig config file and ldconfig command which creates the necessary links and cache to the most recent shared libraries found in the directories specified on the command line, in the file /etc/ld.so.conf, and in the trusted directories such as /lib64 or /usr/lib64 (/lib or /usr/lib on 32 bit systems).
Tutorial details
DifficultyIntermediate (rss)
Root privilegesYes
RequirementsGNU gcc
Time10m
The /etc/ld.so.conf contains lib settings which can be used to add or delete paths. However, you need to simply drop your config file in /etc/ld.so.conf.d/ directory and it will be used by /sbin/ldconfig to configure dynamic linker run time bindings.

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Add Your Path

Create a file called /etc/ld.so.conf.d/myapp.conf:
# vi /etc/ld.so.conf.d/myapp.conf
Add the following path:

/usr/local/lib

Save and close the file.

Activate Your Library Path

You must run the following command to activate path:
# ldconfig

Verify Your New Library Path

# ldconfig -v | less
OR
# ldconfig -v | grep /usr/local/lib
Sample outputs:

/usr/local/lib:
        libGeoIP.so.1 -> libGeoIP.so.1.4.6
        libGeoIPUpdate.so.0 -> libGeoIPUpdate.so.0.0.0
/usr/lib64/mysql:
        libmysqlclient_r.so.15 -> libmysqlclient_r.so.15.0.0
        libmysqlclient.so.15 -> libmysqlclient.so.15.0.0
/lib:
        libutil.so.1 -> libutil-2.5.so

How Do I Delete The Library Path?

Simply, delete the file:
# rm /etc/ld.so.conf.d/myapp.conf
# ldconfig

How Do I Edit The Library Path?

Simply edit the file and reload the changes:
# vi /etc/ld.so.conf.d/myapp.conf
# ldconfig

How Do I Compile Program With Shared Libs And GNU GCC?

You can use the following gcc
$ gcc -Wl,-R/path/to/lib -I/path/to/include -L/path/to/lib -o myAppName mycode.c -llibapp2
See gcc man page for further details.

Further readings:

man ldconfig man ld man gcc

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5 comments… add one
  • Michael Apr 11, 2010 @ 18:45

    Great article.
    Unfortunately in Fedora 12 the (local) manual page of ldconfig is missing :-(

  • Vijay Kanta Aug 11, 2013 @ 11:56

    You don’t cease to amaze me Vivek. Great article to keep my Linux journey going.

  • Anil Sep 17, 2013 @ 23:41

    Great information…
    Thanks a lot.

  • peltouze Jan 7, 2016 @ 14:00

    Old thread but still, I’ll try.
    Can’t we just add any path to LD_LIBRARY_PATH environment variable ?
    (I’m working on a system on which I don’t have root privileges…)

  • Diego Amicabile Aug 16, 2017 @ 11:34

    You are my hero

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