How to Set LD_LIBRARY_PATH in Linux

Linux, with its unfathomable capabilities, has etched itself into the hearts of developers and system administrators. One of the quintessential elements in sculpting a resilient Linux environment is understanding the usage of environment variables, particularly LD_LIBRARY_PATH. This guide will meticulously guide you through setting LD_LIBRARY_PATH, providing you with a grasp of its significance, functionalities, and impeccable strategies to wield it efficiently. Let’s delve in!


LD_LIBRARY_PATH is a critical aspect of Linux system management. It is an environment variable that tells the system where to look for dynamic libraries at runtime. To comprehend the role and significance of LD_LIBRARY_PATH, let’s delve a little deeper into the basics of dynamic libraries and the need for this environment variable.

The Role of Dynamic Libraries in Linux

Dynamic libraries, also known as shared libraries, contain reusable code and data that multiple programs can use simultaneously. When you install software on your Linux system, these libraries are often installed as well.

Dynamic libraries are advantageous for a number of reasons. For instance, they allow code to be shared and changed in a modular way. If a library is updated, programs using that library can benefit from the update without any changes to their own code. Furthermore, because multiple programs can share the same instance of a library in memory, using dynamic libraries can save memory.

However, when a program needs to use a library, it needs to know where to find it. This is where LD_LIBRARY_PATH comes in.

Understanding the Role of LD_LIBRARY_PATH

LD_LIBRARY_PATH is an environment variable that specifies the directories in which the system should look for dynamic libraries. This is especially useful in scenarios where you have multiple versions of a library installed.

For example, suppose you’re developing a program that requires version 1.0 of a specific library, but your system has version 2.0 installed in the standard library directories. In this case, you can install version 1.0 in a different directory and use LD_LIBRARY_PATH to direct your program to that directory.

Structure of LD_LIBRARY_PATH

The structure of LD_LIBRARY_PATH is a colon-separated list of directories. It instructs the system to look for libraries in these directories in the order they are listed. This means that if the same library is located in multiple directories listed in LD_LIBRARY_PATH, the system will use the first one it finds.

For example, suppose you have libraries in /path/to/library1 and /path/to/library2, you would set LD_LIBRARY_PATH like this:

export LD_LIBRARY_PATH=/path/to/library1:/path/to/library2

In this example, the system will first search /path/to/library1 for libraries, and then /path/to/library2. If a library is found in both directories, the version in /path/to/library1 will be used because it is listed first.


Manipulating LD_LIBRARY_PATH is a pivotal task in certain situations, particularly when your application is dependent on a library present in a non-standard location. It provides you with control over which directories are scanned for shared libraries at runtime. The steps for setting LD_LIBRARY_PATH can be bifurcated into two primary categories: temporary and permanent.

Setting LD_LIBRARY_PATH Temporarily

There could be numerous situations when you may need to modify LD_LIBRARY_PATH on a temporary basis. This might be required for debugging, testing, or executing an application that demands a specific library version.

To set LD_LIBRARY_PATH temporarily, you can leverage the export command within the terminal session. This command sets the environment variable for the current shell session only, and the change disappears as soon as you close the terminal or start a new one.

Here’s how you can do it:

export LD_LIBRARY_PATH=/your/custom/directory:$LD_LIBRARY_PATH

In this command, /your/custom/directory is the directory containing the libraries your application needs. The :$LD_LIBRARY_PATH part appends the existing value of LD_LIBRARY_PATH to prevent overwriting any existing directories in the variable.

Setting LD_LIBRARY_PATH Permanently

There could be scenarios where you want the changes to LD_LIBRARY_PATH to persist across sessions and even reboots. In such situations, you can edit your user’s .bashrc file (or the equivalent configuration file for your shell).

Appending the export command to the end of this file ensures that LD_LIBRARY_PATH is set every time a new shell session is started. Here’s the command that accomplishes this:

echo 'export LD_LIBRARY_PATH=/your/custom/directory:$LD_LIBRARY_PATH' >> ~/.bashrc

The >> operator appends the export command to the end of .bashrc. Once you’ve made the change, you need to reload .bashrc to apply it:

source ~/.bashrc

Order of Directories in LD_LIBRARY_PATH

The order of directories in LD_LIBRARY_PATH matters because they are searched in the order they are listed. Therefore, you should place the directories with the most frequently used libraries earlier in the list to optimize the search performance.

For example, if you have two directories /path/to/library1 and /path/to/library2, and library1 is used more frequently, you would set LD_LIBRARY_PATH like this:

export LD_LIBRARY_PATH=/path/to/library1:/path/to/library2

This ensures that library1 is searched before library2, making the library search process more efficient.

Advanced Tips for LD_LIBRARY_PATH

Using Scripts for Context-Specific Scenarios

Shell scripts can be utilized to configure LD_LIBRARY_PATH for specific applications, ensuring that the setting does not impact the entire system.

Example: Running Different Versions of the Same Application

Let’s say you are working on a project that needs different versions of the same library for testing. You could create scripts for each version like this:

For version 1:

export LD_LIBRARY_PATH=/path/to/version1/libs:$LD_LIBRARY_PATH

And for version 2:

export LD_LIBRARY_PATH=/path/to/version2/libs:$LD_LIBRARY_PATH

Example: Using a Script for an Application With Unique Dependencies

If you have an application with unique dependencies that are not shared with other applications, you can create a script that sets the LD_LIBRARY_PATH before launching the application.

export LD_LIBRARY_PATH=/path/to/unique/libs:$LD_LIBRARY_PATH

This script can be executed every time you need to run the application with its unique set of libraries.

Leveraging ldconfig

Using ldconfig to manage the shared library cache can be an elegant and effective way to avoid directly setting LD_LIBRARY_PATH.

Example: Adding Multiple Directories

In some cases, you may need to add multiple directories to the library path. You can create a .conf file containing the paths and then use ldconfig:

echo -e "/path/to/libs1\n/path/to/libs2" | sudo tee /etc/
sudo ldconfig

Example: Removing a Directory from Library Path

If you added a directory previously but now want to remove it, you can simply delete the appropriate .conf file and run ldconfig again:

sudo rm /etc/
sudo ldconfig

This removes the directory from the library path and rebuilds the cache.

Example: Viewing the Current Library Path

You can use ldconfig in conjunction with grep to view the directories currently in the library path. This is particularly useful for verifying that your changes have been applied:

ldconfig -v 2>/dev/null | grep -v ^$'\t'

Utilizing advanced techniques like shell scripts and ldconfig can make managing LD_LIBRARY_PATH and library paths more controlled and streamlined. These methods provide flexibility and precision, crucial in complex environments with varying requirements.

Troubleshooting and Addressing Issues

Resolving Library Conflicts

When working with LD_LIBRARY_PATH, you might stumble upon library conflicts. Here’s an example:

Imagine you have two versions of a library, let’s say The system version resides in /usr/lib, and a newer version is in /home/user/libs. You set LD_LIBRARY_PATH to /home/user/libs, but still, the application uses the system version. This can occur due to the ordering of directories in LD_LIBRARY_PATH.

Potential Fix: Adjusting Order

You might want to adjust the order of directories in LD_LIBRARY_PATH. For instance:

export LD_LIBRARY_PATH=/home/user/libs:$LD_LIBRARY_PATH

This ensures that /home/user/libs is searched before the directories in the existing LD_LIBRARY_PATH.

Potential Fix: Version Scripting

Another strategy is to use version-scripting and symbol versioning to ensure that the application links against the correct version of the library. You would need to refer to the linker documentation and make adjustments to the build process of your application.

Potential Fix: Dynamic Linker Run-time Bindings

Using the LD_PRELOAD environment variable, you can specify a library to be loaded before any others. This can be used to force an application to use a specific version of a library. For example:

export LD_PRELOAD=/home/user/libs/

Diagnosing Issues with ldd

Sometimes, despite setting LD_LIBRARY_PATH, your application might not run correctly due to library issues. This is where the ldd command comes in handy.

Example: Missing Library

Let’s say you’re trying to run an application, and you get an error message about a missing library. Run:

ldd /path/to/your/program

If you see an output like this: => not found

This indicates that the library is missing.

Potential Fix: Locating and Adding the Library

Locate the missing library, and then set LD_LIBRARY_PATH accordingly:

export LD_LIBRARY_PATH=/path/to/library:$LD_LIBRARY_PATH

Example: Incompatible Library Version

In some cases, an incompatible library version could be causing issues. If ldd indicates that an incorrect version of a library is being loaded, you might need to specify the correct directory containing the compatible version in LD_LIBRARY_PATH.

Potential Fix: Specifying the Correct Library

Locate the correct version of the library, and then adjust LD_LIBRARY_PATH to use it:

export LD_LIBRARY_PATH=/path/containing/correct/version:$LD_LIBRARY_PATH

The ldd command, when used effectively, can shed light on library issues and is an indispensable tool in your Linux troubleshooting arsenal. The key is to keenly observe the output of ldd, understand the nature of the issue, and then judiciously apply the most appropriate fix.

Best Practices for LD_LIBRARY_PATH Configuration

Limiting the Scope of LD_LIBRARY_PATH

When setting LD_LIBRARY_PATH, it’s wise to scope the variable as narrowly as possible. Set it only for the sessions or scripts where it’s needed, rather than system-wide.

Validating Library Compatibility

Ensure that the libraries in the directories specified in LD_LIBRARY_PATH are compatible with the applications that will be using them. This includes checking for the correct versions and architectures.

Maintaining Documentation for Configuration Changes

Maintain documentation for any changes made to LD_LIBRARY_PATH. This includes why the changes were made, which directories were added, and any known issues or conflicts. This can be invaluable for troubleshooting and maintenance.


Setting LD_LIBRARY_PATH in Linux is a potent technique for directing the system in its quest for dynamic libraries. It’s paramount to approach this task with a discerning eye, cognizant of the potential repercussions and the advanced tools at your disposal. Through judicious use and an in-depth understanding of the intricacies involved, you can harness LD_LIBRARY_PATH to deftly navigate the rich landscape of Linux environments.