一、问题描述
编写一个与libpcap有关的程序：test_libpcap.cpp，编译test_libpcap.o成功。
注：之前已经成功安装libpcap，libpcap.so.1.5.3的路径是：/home/test/work/lib；
test_libpcap.cpp的路径是/home/test/work/test_libpcap。
运行test_libpcap.o出现以下提示：
test_libpcap.o: error while loading shared libraries: libpcap.so.1.5.3: cannot open shared object file: No such file or directory
二、问题解决
注：以下操作均需要root权限
1.定位“libpcap.so.1.5.3”的路径
# locate libpcap.so.1.5.3
/home/test/work/lib/libpcap.so.1.5.3
/usr/lib/i386-linux-gnu/libpcap.so.1.5.3
/usr/local/lib/libpcap.so.1.5.3
2.将上述路径中的“/home/test/work/lib/libpcap.so.1.5.3”加入“/etc/ld.so.conf.d”中
# cd /etc/ld.so.conf.d
# ls
i686-linux-gnu.conf libc.conf
# echo "# libpcap default configuration" >> libpcap.conf
# echo "/home/test/work/lib/libpcap.so.1.5.3" >> libpcap.conf
3.运行ldconfig命令
# /sbin/ldconfig
4.再次运行test_libpcap.o，成功。
三、参考信息
1.man locate
locate(1) General Commands Manual locate(1)
NAME
locate - find files by name
SYNOPSIS
locate [OPTION]... PATTERN...
DESCRIPTION
locate reads one or more databases prepared by updatedb(8) and writes
file names matching at least one of the PATTERNs to standard output,
one per line.
If --regex is not specified, PATTERNs can contain globbing characters.
If any PATTERN contains no globbing characters, locate behaves as if
the pattern were *PATTERN*.
By default, locate does not check whether files found in database still
exist (but it does require all parent directories to exist if the data‐
base was built with --require-visibility no). locate can never report
files created after the most recent update of the relevant database.
EXIT STATUS
locate exits with status 0 if any match was found or if locate was
invoked with one of the --limit 0, --help, --statistics or --version
options. If no match was found or a fatal error was encountered,
locate exits with status 1.
Errors encountered while reading a database are not fatal, search con‐
tinues in other specified databases, if any.
OPTIONS
-A, --all
Print only entries that match all PATTERNs instead of requiring
only one of them to match.
-b, --basename
Match only the base name against the specified patterns. This
is the opposite of --wholename.
-c, --count
Instead of writing file names on standard output, write the num‐
ber of matching entries only.
-d, --database DBPATH
Replace the default database with DBPATH. DBPATH is a :-sepa‐
rated list of database file names. If more than one --database
option is specified, the resulting path is a concatenation of
the separate paths.
An empty database file name is replaced by the default database.
A database file name - refers to the standard input. Note that
a database can be read from the standard input only once.
-e, --existing
Print only entries that refer to files existing at the time
locate is run.
-L, --follow
When checking whether files exist (if the --existing option is
specified), follow trailing symbolic links. This causes broken
symbolic links to be omitted from the output.
This is the default behavior. The opposite can be specified
using --nofollow.
-h, --help
Write a summary of the available options to standard output and
exit successfully.
-i, --ignore-case
Ignore case distinctions when matching patterns.
-l, --limit, -n LIMIT
Exit successfully after finding LIMIT entries. If the --count
option is specified, the resulting count is also limited to
LIMIT.
-m, --mmap
Ignored, for compatibility with BSD and GNU locate.
-P, --nofollow, -H
When checking whether files exist (if the --existing option is
specified), do not follow trailing symbolic links. This causes
broken symbolic links to be reported like other files.
This is the opposite of --follow.
-0, --null
Separate the entries on output using the ASCII NUL character
instead of writing each entry on a separate line. This option
is designed for interoperability with the --null option of GNU
xargs(1).
-S, --statistics
Write statistics about each read database to standard output
instead of searching for files and exit successfully.
-q, --quiet
Write no messages about errors encountered while reading and
processing databases.
-r, --regexp REGEXP
Search for a basic regexp REGEXP. No PATTERNs are allowed if
this option is used, but this option can be specified multiple
times.
--regex
Interpret all PATTERNs as extended regexps.
-s, --stdio
Ignored, for compatibility with BSD and GNU locate.
-V, --version
Write information about the version and license of locate on
standard output and exit successfully.
-w, --wholename
Match only the whole path name against the specified patterns.
This is the default behavior. The opposite can be specified
using --basename.
EXAMPLES
To search for a file named exactly NAME (not *NAME*), use
locate -b '\NAME'
Because \ is a globbing character, this disables the implicit replace‐
ment of NAME by *NAME*.
FILES
/var/lib/mlocate/mlocate.db
The database searched by default.
ENVIRONMENT
LOCATE_PATH
Path to additional databases, added after the default database
or the databases specified using the --database option.
NOTES
The order in which the requested databases are processed is unspeci‐
fied, which allows locate to reorder the database path for security
reasons.
locate attempts to be compatible to slocate (without the options used
for creating databases) and GNU locate, in that order. This is the
reason for the impractical default --follow option and for the confus‐
ing set of --regex and --regexp options.
The short spelling of the -r option is incompatible to GNU locate,
where it corresponds to the --regex option. Use the long option names
to avoid confusion.
The LOCATE_PATH environment variable replaces the default database in
BSD and GNU locate, but it is added to other databases in this imple‐
mentation and slocate.
AUTHOR
Miloslav Trmac <mitr@redhat.com>
SEE ALSO
updatedb(8)
mlocateSep locate(1)
2.man ldconfig
LDCONFIG(8) Linux Programmer's Manual LDCONFIG(8)
NAME
ldconfig - configure dynamic linker run-time bindings
SYNOPSIS
/sbin/ldconfig [ -nNvXV ] [ -f conf ] [ -C cache ] [ -r root ] direc‐
tory ...
/sbin/ldconfig -l [ -v ] library ...
/sbin/ldconfig -p
DESCRIPTION
ldconfig creates the necessary links and cache to the most recent
shared libraries found in the directories specified on the command
line, in the file /etc/ld.so.conf, and in the trusted directories (/lib
and /usr/lib). The cache is used by the run-time linker, ld.so or ld-
linux.so. ldconfig checks the header and filenames of the libraries it
encounters when determining which versions should have their links
updated.
ldconfig will attempt to deduce the type of ELF libs (i.e., libc5 or
libc6/glibc) based on what C libs, if any, the library was linked
against.
Some existing libs do not contain enough information to allow the
deduction of their type. Therefore, the /etc/ld.so.conf file format
allows the specification of an expected type. This is used only for
those ELF libs which we can not work out. The format is
"dirname=TYPE", where TYPE can be libc4, libc5, or libc6. (This syntax
also works on the command line.) Spaces are not allowed. Also see the
-p option. ldconfig should normally be run by the superuser as it may
require write permission on some root owned directories and files.
OPTIONS
-v Verbose mode. Print current version number, the name of each
directory as it is scanned, and any links that are created.
Overrides quiet mode.
-n Only process directories specified on the command line. Don't
process the trusted directories (/lib and /usr/lib) nor those
specified in /etc/ld.so.conf. Implies -N.
-N Don't rebuild the cache. Unless -X is also specified, links are
still updated.
-X Don't update links. Unless -N is also specified, the cache is
still rebuilt.
-f conf
Use conf instead of /etc/ld.so.conf.
-C cache
Use cache instead of /etc/ld.so.cache.
-r root
Change to and use root as the root directory.
-l Library mode. Manually link individual libraries. Intended for
use by experts only.
-p Print the lists of directories and candidate libraries stored in
the current cache.
FILES
/lib/ld.so run-time linker/loader
/etc/ld.so.conf File containing a list of colon, space, tab, new‐line, or comma-separated directories in which to search for libraries.
/etc/ld.so.cache File containing an ordered list of libraries found in the directories specified in /etc/ld.so.conf, as well as those found in /lib and /usr/lib.
SEE ALSO
ldd(1), ld.so(8)
COLOPHON
This page is part of release 3.54 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU LDCONFIG(8)
Linux ldconfig命令：http://www.linuxdiyf.com/linux/12506.html
ldconfig命令的作用：http://www.linuxdiyf.com/linux/223.html