LDD(1) BSD General Commands Manual LDD(1)NAME
ldd -- list dynamic object dependencies
SYNOPSIS
ldd [-o] [-f format] program ...
DESCRIPTION
ldd displays all shared objects that are needed to run the given program. Contrary to nm(1), the list includes ``indirect'' dependencies
that are the result of needed shared objects which themselves depend on yet other shared objects. Zero, one or two -f options may be given.
The argument is a format string passed to rtld(1) and allows customization of ldd's output. The first format argument is used for library
objects and defaults to " -l%o.%m => %p
". The second format argument is used for non-library objects and defaults to " %o => %p
".
These arguments are interpreted as format strings a la printf(3) to customize the trace output and allow ldd to be operated as a filter more
conveniently. The following conversions can be used:
%a The main program's name (also known as ``__progname'').
%A The value of the environment variable LD_TRACE_LOADED_OBJECTS_PROGNAME in a.out and the program name from the argument vector from elf.
%o The library name.
%m The library's major version number.
%n The library's minor version number (a.out only, ignored in elf).
%p The full pathname as determined by rtld's library search rules.
%x The library's load address
Additionally,
and are recognized and have their usual meaning.
The -o option is an alias for -f %a:-l%o.%m => %p
, which makes ldd behave analogously to nm -o.
SEE ALSO ld(1), ld.elf_so(1), nm(1), rtld(1)HISTORY
A ldd utility first appeared in SunOS 4.0, it appeared in its current form in NetBSD 0.9A.
BUGS
The a.out ldd actually runs the program it has been requested to analyze which in specially constructed environments can have security impli-
cations.
BSD September 7, 2009 BSD
Check Out this Related Man Page
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 is the following:
$ ldd /bin/ls
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 (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).)
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 report 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 4.15 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/.
2017-09-15 LDD(1)