ldd(1) General Commands 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 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 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 at-
tempt to obtain the dependency information by attempting to directly ex-
ecute 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. (Before glibc 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 ex-
ecutable.
OPTIONS
--version
Print the version number of ldd.
--verbose
-v Print all information, including, for example, symbol versioning
information.
--unused
-u Print unused direct dependencies. (Since glibc 2.3.4.)
--data-relocs
-d Perform relocations and report any missing objects (ELF only).
--function-relocs
-r 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)
Linux man-pages 6.9.1 2024-05-02 ldd(1)
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