| .\" Copyright 1995-2000 David Engel (david@ods.com) |
| .\" Copyright 1995 Rickard E. Faith (faith@cs.unc.edu) |
| .\" Copyright 2000 Ben Collins (bcollins@debian.org) |
| .\" Redone for GLibc 2.2 |
| .\" Copyright 2000 Jakub Jelinek (jakub@redhat.com) |
| .\" Corrected. |
| .\" and Copyright (C) 2012, 2016, Michael Kerrisk <mtk.manpages@gmail.com> |
| .\" |
| .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE) |
| .\" Do not restrict distribution. |
| .\" May be distributed under the GNU General Public License |
| .\" %%%LICENSE_END |
| .\" |
| .TH LDD 1 2019-03-06 "" "Linux Programmer's Manual" |
| .SH NAME |
| ldd \- print shared object dependencies |
| .SH SYNOPSIS |
| .BR ldd " [\fIoption\fP]... \fIfile\fP..." |
| .SH DESCRIPTION |
| .B 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: |
| .PP |
| .in +2n |
| .EX |
| $ \fBldd /bin/ls\fP |
| 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) |
| .EE |
| .in |
| .PP |
| In the usual case, |
| .B ldd |
| invokes the standard dynamic linker (see |
| .BR ld.so (8)) |
| with the |
| .B 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 |
| .BR ld.so (8)) |
| and load the objects that satisfy those dependencies. |
| For each dependency, |
| .B ldd |
| displays the location of the matching object |
| and the (hexadecimal) address at which it is loaded. |
| (The |
| .I linux-vdso |
| and |
| .I ld-linux |
| shared dependencies are special; see |
| .BR vdso (7) |
| and |
| .BR ld.so (8).) |
| .\" |
| .SS Security |
| Be aware that in some circumstances |
| (e.g., where the program specifies an ELF interpreter other than |
| .IR ld-linux.so ), |
| .\" The circumstances are where the program has an interpreter |
| .\" other than ld-linux.so. In this case, ldd tries to execute the |
| .\" program directly with LD_TRACE_LOADED_OBJECTS=1, with the |
| .\" result that the program interpreter gets control, and can do |
| .\" what it likes, or pass control to the program itself. |
| .\" Much more detail at |
| .\" http://www.catonmat.net/blog/ldd-arbitrary-code-execution/ |
| some versions of |
| .B 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. |
| .\" Mainline glibc's ldd allows this possibility (the line |
| .\" try_trace "$file" |
| .\" in glibc 2.15, for example), but many distro versions of |
| .\" ldd seem to remove that code path from the script. |
| (In glibc versions before 2.27, |
| .\" glibc commit eedca9772e99c72ab4c3c34e43cc764250aa3e3c |
| the upstream |
| .B ldd |
| implementation did this for example, |
| although most distributions provided a modified version that did not.) |
| .PP |
| Thus, you should |
| .I never |
| employ |
| .B ldd |
| on an untrusted executable, |
| since this may result in the execution of arbitrary code. |
| A safer alternative when dealing with untrusted executables is: |
| .PP |
| .in +4n |
| .EX |
| $ \fBobjdump \-p /path/to/program | grep NEEDED\fP |
| .EE |
| .in |
| .PP |
| Note, however, that this alternative shows only the direct dependencies |
| of the executable, while |
| .B ldd |
| shows the entire dependency tree of the executable. |
| .SH OPTIONS |
| .TP |
| .B \-\-version |
| Print the version number of |
| .BR ldd . |
| .TP |
| .BR \-v ", " \-\-verbose |
| Print all information, including, for example, |
| symbol versioning information. |
| .TP |
| .BR \-u ", " \-\-unused |
| Print unused direct dependencies. |
| (Since glibc 2.3.4.) |
| .TP |
| .BR \-d ", " \-\-data\-relocs |
| Perform relocations and report any missing objects (ELF only). |
| .TP |
| .BR \-r ", " \-\-function\-relocs |
| Perform relocations for both data objects and functions, and |
| report any missing objects or functions (ELF only). |
| .TP |
| .B \-\-help |
| Usage information. |
| .\" .SH NOTES |
| .\" The standard version of |
| .\" .B ldd |
| .\" comes with glibc2. |
| .\" Libc5 came with an older version, still present |
| .\" on some systems. |
| .\" The long options are not supported by the libc5 version. |
| .\" On the other hand, the glibc2 version does not support |
| .\" .B \-V |
| .\" and only has the equivalent |
| .\" .BR \-\-version . |
| .\" .LP |
| .\" The libc5 version of this program will use the name of a library given |
| .\" on the command line as-is when it contains a \(aq/\(aq; otherwise it |
| .\" searches for the library in the standard locations. |
| .\" To run it |
| .\" on a shared library in the current directory, prefix the name with "./". |
| .SH BUGS |
| .B ldd |
| does not work on a.out shared libraries. |
| .PP |
| .B ldd |
| does not work with some extremely old a.out programs which were |
| built before |
| .B ldd |
| support was added to the compiler releases. |
| If you use |
| .B ldd |
| on one of these programs, the program will attempt to run with |
| .I argc |
| = 0 and the results will be unpredictable. |
| .\" .SH AUTHOR |
| .\" David Engel. |
| .\" Roland McGrath and Ulrich Drepper. |
| .SH SEE ALSO |
| .BR pldd (1), |
| .BR sprof (1), |
| .BR ld.so (8), |
| .BR ldconfig (8) |