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 pro-
gram or shared object specified on the command line. An example of its
use and output (using sed(1) to trim leading white space for readabil-
ity 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 de-
pendencies, 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 de-
pendencies 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 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 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 re-
port any missing objects 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 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.
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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