LDD(1) Linux Programmer's Manual LDD(1)
ldd - print shared object dependencies
ldd [option]... file...
ldd prints the shared objects (shared libraries) required by each program or shared object specified on the command line. An example of
its use and output is the following:
$ ldd /bin/ls
libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f87e5459000)
libcap.so.2 => /lib64/libcap.so.2 (0x00007f87e5254000)
libc.so.6 => /lib64/libc.so.6 (0x00007f87e4e92000)
libpcre.so.1 => /lib64/libpcre.so.1 (0x00007f87e4c22000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f87e4a1e000)
libattr.so.1 => /lib64/libattr.so.1 (0x00007f87e4817000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f87e45fa000)
In the usual case, ldd invokes the standard dynamic linker (see ld.so(8)) with the LD_TRACE_LOADED_OBJECTS environment variable set to 1.
This causes the dynamic linker to inspect the program's dynamic dependencies, and find (according to the rules described in ld.so(8)) and
load the objects that satisfy those dependencies. For each dependency, ldd displays the location of the matching object and the (hexadeci-
mal) address at which it is loaded. (The linux-vdso and ld-linux shared dependencies are special; see vdso(7) and ld.so(8).)
Be aware that in some circumstances (e.g., where the program specifies an ELF interpreter other than ld-linux.so), some versions of ldd may
attempt to obtain the dependency information by attempting to directly execute the program, which may lead to the execution of whatever
code is defined in the program's ELF interpreter, and perhaps to execution of the program itself. (In glibc versions before 2.27, the
upstream ldd implementation did this for example, although most distributions provided a modified version that did not.)
Thus, you should never employ ldd on an untrusted executable, since this may result in the execution of arbitrary code. A safer alterna-
tive when dealing with untrusted executables is:
$ objdump -p /path/to/program | grep NEEDED
Note, however, that this alternative shows only the direct dependencies of the executable, while ldd shows the entire dependency tree of
Print the version number of ldd.
Print all information, including, for example, symbol versioning information.
Print unused direct dependencies. (Since glibc 2.3.4.)
Perform relocations and report any missing objects (ELF only).
Perform relocations for both data objects and functions, and report any missing objects or functions (ELF only).
--help Usage information.
ldd does not work on a.out shared libraries.
ldd does not work with some extremely old a.out programs which were built before ldd support was added to the compiler releases. If you
use ldd on one of these programs, the program will attempt to run with argc = 0 and the results will be unpredictable.
pldd(1), sprof(1), ld.so(8), ldconfig(8)
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