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LDD(1) Linux Programmer's Manual LDD(1)
NAME
ldd - print shared object dependencies
SYNOPSIS
ldd [option]... file...
DESCRIPTION
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 (using sed(1) to trim
leading white space for readability in this page) is the following:
$ ldd /bin/ls | sed 's/^ */ /'
linux-vdso.so.1 (0x00007ffcc3563000)
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)
/lib64/ld-linux-x86-64.so.2 (0x00005574bf12e000)
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 (hexadecimal) address at which it is
loaded. (The linux-vdso and ld-linux shared dependencies are special; see vdso(7) and
ld.so(8).)
Security
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 infor-
mation 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 alternative 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 the executable.
OPTIONS
--version
Print the version number of ldd.
-v, --verbose
Print all information, including, for example, symbol versioning information.
-u, --unused
Print unused direct dependencies. (Since glibc 2.3.4.)
-d, --data-relocs
Perform relocations and report any missing objects (ELF only).
-r, --function-relocs
Perform relocations for both data objects and functions, and report any missing ob-
jects or functions (ELF only).
--help Usage information.
BUGS
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 sup-
port 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.
SEE ALSO
pldd(1), sprof(1), ld.so(8), ldconfig(8)
COLOPHON
This page is part of release 5.10 of the Linux man-pages project. A description of the
project, information about reporting bugs, and the latest version of this page, can be
found at https://www.kernel.org/doc/man-pages/.
2019-03-06 LDD(1)
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