ldd Command on Linux with Examples

ldd Command on Linux

In the realm of Linux system administration and software development, understanding the intricacies of how applications interact with shared libraries is paramount. The ldd command stands as a pivotal tool in this exploration, offering users a window into the shared library dependencies of executable files and shared objects. This guide delves into the syntax, usage, and practical examples of the ldd command, equipping you with the knowledge to navigate the complexities of library dependencies confidently.

Understanding the ldd Command

What is the ldd Command?

At its core, the ldd command is a utility that reveals the shared library dependencies of executable files or shared objects on Linux systems. This functionality is crucial for debugging and optimizing applications, ensuring they have access to the necessary libraries at runtime.

Syntax and Basic Usage

The syntax for the ldd command is straightforward:

ldd [options] /path/to/program

To display the shared library dependencies of a program, such as /usr/bin/grep, you would execute:

ldd /usr/bin/grep

This command outputs a list of shared libraries required by grep, along with their locations and memory addresses.

Common Options and Their Uses

The ldd command offers several options to refine its output:

  • -v (verbose): Provides detailed information about shared libraries.
  • -u (unused): Lists unused direct dependencies.
  • -d and -r (relocations): Check for missing objects or functions, crucial for ELF executables.

Advanced Usage and Examples

Displaying Shared Library Dependencies

To view the dependencies of the ls command, simply run:

ldd /bin/ls

This command lists all shared libraries ls depends on, a fundamental step in troubleshooting and optimization.

Verbose Output

For an in-depth analysis, including symbol versioning data, the -v option becomes invaluable:

ldd -v /usr/bin/grep

Checking for Unused Direct Dependencies

Identifying unused dependencies can streamline applications. Use the -u option as follows:

ldd -u /usr/bin/grep

Performing Relocations

The -d and -r options are instrumental in identifying missing elements essential for the application’s execution:

ldd -d /usr/bin/grep
ldd -r /usr/bin/grep

Security Considerations

It is important to note that ldd should not be used on untrusted binaries. In some cases, ldd may execute the program directly to obtain dependency information, which could lead to the execution of arbitrary code if the binary is malicious. As an alternative, you can use objdump with grep to safely list the dependencies:

objdump -p /path/to/program | grep NEEDED

This method does not execute any code from the binary and is therefore safer for inspecting untrusted executables.

Troubleshooting with ldd

When an executable fails to run due to missing libraries, ldd can help identify which libraries are missing and where they should be located. However, if ldd reports “not a dynamic executable,” it indicates that the file is not a dynamically linked executable and ldd cannot be used with it.


The ldd command is an indispensable tool for anyone involved in Linux system administration or software development. Its ability to unveil the shared library dependencies of executables aids in debugging, optimization, and ensuring application stability. While its power is undeniable, users must navigate its use with an understanding of the potential security implications. By leveraging ldd alongside alternative tools and practices, one can achieve a comprehensive understanding of application dependencies in Linux environments.


r00t is a seasoned Linux system administrator with a wealth of experience in the field. Known for his contributions to, r00t has authored numerous tutorials and guides, helping users navigate the complexities of Linux systems. His expertise spans across various Linux distributions, including Ubuntu, CentOS, and Debian. r00t's work is characterized by his ability to simplify complex concepts, making Linux more accessible to users of all skill levels. His dedication to the Linux community and his commitment to sharing knowledge makes him a respected figure in the field.
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