Linux ldd Command: List Dynamic Library Dependencies of a Program

The ldd command in Linux – List Dynamic Dependencies – provides a list of the dynamic dependencies that a specific program needs. It will return the shared library name and its expected location on disk.

Examples:

$ ldd /bin/bash
libreadline.so.4 => /lib/libreadline.so.4 (0x4001c000)
libhistory.so.4 => /lib/libhistory.so.4 (0x40049000)
libncurses.so.5 => /lib/libncurses.so.5 (0x40050000)
libdl.so.2 => /lib/libdl.so.2 (0x40096000)
libc.so.6 => /lib/libc.so.6 (0x40099000)
/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

In this example, the bash program needs all these libraries to function.

The ldd command is important to determine which are the necessary libraries of an executable.

When an error occurs during the execution of a program, complaining about a missing library or incorrect version, the ldd program can be used to determine which library and its version that should be installed for the program to work correctly.

The program that configures the directories containing the shared libraries is ldconfig.

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