.\" $FreeBSD$
.\"
.Dd March 21, 2023
.Dt LDD 1
.Os
.Sh NAME
.Nm ldd
.Nd list dynamic object dependencies
.Sh SYNOPSIS
.Nm
.Op Fl a
.Op Fl f Ar format Op Fl f Ar format
.Ar program ...
.Sh DESCRIPTION
The
.Nm
utility displays all shared objects that are needed to run the given program or
to load the given shared object.
Contrary to
.Xr nm 1 ,
the list includes
.Dq indirect
dependencies that are the result of needed shared objects which themselves
depend on yet other shared objects.
.Pp
Zero, one or two
.Fl f
options may be given.
The argument is a format string passed to
.Xr rtld 1
and allows customization of
.Nm Ns 's
output.
If one is given, it sets
.Ev LD_TRACE_LOADED_OBJECTS_FMT1 .
If two are given, they set
.Ev LD_TRACE_LOADED_OBJECTS_FMT1
and
.Ev LD_TRACE_LOADED_OBJECTS_FMT2 ,
respectively.
See
.Xr rtld 1
for details, including a list of recognized conversion characters.
.Pp
The
.Fl a
option displays the list of all objects that are needed by each loaded
object.
.Sh IMPLEMENTATION NOTES
.Nm
lists the dependencies of an executable by setting
.Xr rtld 1
environment variables and running the executable in a child process.
If the executable is corrupt or invalid,
.Nm
may therefore fail without providing any diagnostic error messages.
.Sh EXAMPLES
The following is an example of a shell pipeline which uses the
.Fl f
option.
It will print a report of all ELF binaries in the current directory,
which link against the old libc.so.6:
.Dl "find . -type f | xargs file -F ' ' | grep 'ELF.*dynamically' | cut -f1 -d' ' | xargs ldd -f '%A %o\en' | grep -F libc.so.6"
.Sh SEE ALSO
.Xr ld 1 ,
.Xr nm 1 ,
.Xr readelf 1 ,
.Xr rtld 1
.Sh HISTORY
A
.Nm
utility first appeared in SunOS 4.0, it appeared in its current form in
.Fx 1.1 .