freebsd-dev/usr.bin/ldd/ldd.1
Edwin Groothuis fffd993df2 On 64 bit architectures, you can run 32 bit executables and the rtld can trace them, but ldd(1) doesn't know yet how to detect them:
[/] root@ed-exigent>ldd `which httpd`
    ldd: /usr/local/sbin/httpd: can't read program header
    ldd: /usr/local/sbin/httpd: not a dynamic executable

    But...

    [/] root@ed-exigent>LD_32_TRACE_LOADED_OBJECTS==1 `which httpd`
    libm.so.4 => /lib32//libm.so.4 (0x280c8000)
    libaprutil-1.so.2 => /usr/local/lib/libaprutil-1.so.2 (0x280de000)
    libexpat.so.6 => /usr/local/lib/libexpat.so.6 (0x280f2000)
    libiconv.so.3 => /usr/local/lib/libiconv.so.3 (0x28110000)
    libapr-1.so.2 => /usr/local/lib/libapr-1.so.2 (0x281fd000)
    libcrypt.so.3 => /lib32//libcrypt.so.3 (0x2821d000)
    libpthread.so.2 => not found (0x0)
    libc.so.6 => /lib32//libc.so.6 (0x28235000)
    libpthread.so.2 => /usr/lib32/libpthread.so.2 (0x2830d000)

Added support in ldd(1) for the LD_32_xxx environment variables if
the architecture of the machine is >32 bits. If we ever go to 128
bit architectures this excercise will have to be repeated but thanks
to earlier commits today it will be relative simple.

PR:		bin/124906
Submitted by:	edwin
Approved by:	bde (mentor)
MFC after:	1 week
2008-07-03 22:37:51 +00:00

87 lines
1.8 KiB
Groff

.\" $FreeBSD$
.\"
.Dd May 15, 2008
.Dt LDD 1
.Os
.Sh NAME
.Nm ldd
.Nd list dynamic object dependencies
.Sh SYNOPSIS
.Nm
.Op Fl a
.Op Fl v
.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.
This option does not work with
.Xr a.out 5
binaries.
.Pp
The
.Fl v
option displays a verbose listing of the dynamic linking headers
encoded in the executable.
See the source code and include
files for the definitive meaning of all the fields.
.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 libc.so.6:
.Dl "find . -type f | xargs -n1 file -F " " | grep ELF | cut -f1 -d' ' | xargs ldd -f '%A %o\en' | grep libc.so.6"
.Sh BUGS
On 64 bit architectures, dlopen() cannot open 32 bit dynamic libraries,
so
.Nm
will show the error
.Qq "unsupported file layout" .
.Sh SEE ALSO
.Xr ld 1 ,
.Xr nm 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 .
.Pp
The
.Fl v
support is based on code written by
.An John Polstra Aq jdp@polstra.com