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99 lines
2.6 KiB
Groff
99 lines
2.6 KiB
Groff
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.Dd October 3, 1993
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.Dt LDCONFIG 8
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.Os NetBSD 0.9
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.Sh NAME
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.Nm ldconfig
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.Nd configure the shared library cache
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.Sh SYNOPSIS
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.Nm ldconfig
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.Op Fl rsv
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.Op Ar directory Ar ...
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.Sh DESCRIPTION
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.Nm
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is used to prepare a set of
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.Dq hints
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for use by the run-time linker
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.Xr ld.so
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to facilitate quick lookup of shared libraries available in multiple
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directories. It scans a set of built-in system directories and any
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.Ar directories
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specified on the command line (in the given order) looking for shared
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libraries and stores the results in the file
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.Xr /var/run/ld.so.hints
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to forstall the overhead that would otherwise result from the
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directory search operations
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.Xr ld.so
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would have to perform to load the required shared libraries.
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.Pp
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The shared libraries so found will be automatically available for loading
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if needed by the program being prepared for execution. This obviates the need
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for storing search paths within the executable.
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.Pp
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The
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.Ev LD_LIBRARY_PATH
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environment variable can be used to override the use of
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directories (or the order thereof) from the cache or to specify additional
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directories where shared libraries might be found.
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.Ev LD_LIBRARY_PATH
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is a
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.Sq \:
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separated list of directory paths which are searched by
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.Xr ld.so
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when it needs to load a shared library. It can be viewed as the run-time
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equivalent of the
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.Fl L
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switch of
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.Xr ld.
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.Pp
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.Nm Ldconfig
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is typically run as part of the boot sequence.
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.Pp
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The following options recognized by
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.Nm ldconfig:
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.Bl -tag -width indent
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.It Fl r
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Lists the current contents of
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.Xr ld.so.hints
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on the standard output. The hints file will not be modified.
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.It Fl s
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Do not scan
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.Nm ldconfig
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's builtin system directories
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.Sq /usr/lib
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and
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.Sq /usr/local/lib
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for shared libraries.
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.It Fl v
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Switch on verbose mode.
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.Sh Security
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Special care must be taken when loading shared libraries into the address
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space of
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.Ev set-user-Id
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programs. Whenever such a program is run,
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.Xr ld.so
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will only load shared libraries from the
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.Ev ld.so.hints
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file. In particular, the
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.Ev LD_LIBRARY_PATH
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is not used to search for libraries. Thus, the role of ldconfig is dual. In
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addition to building a set of hints for quick lookup, it also serves to
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specify the trusted collection of directories from which shared objects can
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be safely loaded. It is presumed that the set of directories specified to
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.Nm ldconfig
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are under control of the system's administrator.
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.Xr ld.so
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further assists set-user-Id programs by erasing the
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.Ev LD_LIBRARY_PATH
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from the environment.
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.Sh FILES
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.Xr /var/run/ld.so.hints
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.Sh SEE ALSO
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.Xr ld 1 ,
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.Xr link 5
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.Sh HISTORY
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A
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.Nm
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utility first appeared in SunOS 4.0, it appeared in its current form
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in NetBSD 0.9a.
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