Free LPI Linux Certification in a Nutshell by Adam Haeder; Stephen Addison Schneiter; Bruno Gomes Pessanha; James Stanger

/lib/ld-linux.so.2 (0x40000000)

Name
    ldconfig
    Syntax
ldconfig [
options
]
lib_dirs
    Description
    Update the ld.so cache file with shared
     libraries specified on the command line in lib_dirs , in trusted directories /usr/lib and /lib , and in
     the directories found in /etc/ld.so.conf .
    Frequently used options
    -p
Display the contents of the current cache instead of
     recreating it.
-v
Verbose mode. Display progress during execution.
    Example 1
    Examine the contents of the ld.so library
     cache:
# ldconfig -p 144 libs found in cache '/etc/ld.so.cache'
    libz.so.1 (libc6) => /usr/lib/libz.so.1
    libuuid.so.1 (libc6) => /lib/libuuid.so.1
    libutil.so.1 (libc6, OS ABI: Linux 2.2.5) => /lib/libutil.so.1
    libutil.so (libc6, OS ABI: Linux 2.2.5) => /usr/lib/libutil.so \
    libthread_db.so.1 (libc6, OS ABI: Linux 2.2.5) => /lib/libthread_db.so.1
    libthread_db.so (libc6, OS ABI: Linux 2.2.5) => /usr/lib/libthread_db.so
    Example 2
    Look for a specific library entry in the cache:
# ldconfig -p | grep ncurses libncurses.so.5 (libc6) => /usr/lib/libncurses.so.5
    Example 3
    Rebuild the cache:
# ldconfig
    After /usr/local/lib is added, ld.so.conf might look like this:
/usr/lib
/usr/i486-linux-libc5/lib
/usr/X11R6/lib
/usr/local/lib
    Next, ldconfig is run to include
     libraries found in /usr/local/lib in /etc/ld.so.cache . It is important to run ldconfig after any changes in system libraries
     to be sure that the cache is up-to-date.

Objective 4: Use Debian Package Management
    The Debian package management system is a versatile and
    automated suite of tools used to acquire and manage software packages for
    Debian Linux. The system automatically handles many of the management
    details associated with interdependent software running on your
    system.
    Debian Package Management Overview
    Each Debian package contains program and configuration files,
     documentation, and noted dependencies on other packages. The names of
     Debian packages have three common elements, including:
    Package name
A Debian package name is short and descriptive. When
     multiple words are used in the name, they are separated by
     hyphens. Typical names include binutils , kernel-source , and telnet .
Version number
Each package has a version. Most package versions are the
     same as that of the software they contain. The format of package
     versions varies from package to package, but most are numeric
     (
major.minor.patchlevel
).
A file extension
By default, all Debian packages end with the .deb file extension.
    Figure 5-1 illustrates a Debian package name.
    Figure 5-1. The structure of a Debian GNU/Linux package name
    Managing Debian Packages
    The originalDebian package management tool is dpkg , which operates directly on .deb package files and can be used to automate the
     installation and maintenance of software packages. The alternative apt-get tool operates using package names,
     obtaining them from a predefined source (such as CD-ROMs, FTP sites,
     etc.). Both tools work from the command line.
    The dselect command offers an interactive
     menu that allows the administrator to select from a list of available
     packages and mark them for subsequent installation. The alien command allows the use of non-Debian
     packages, such as the Red Hat RPM format.
    For complete information on Debian package management commands,
     see details in their respective manpages.

Name
    dpkg
    Syntax
dpkg [
options
]
action
    Description
    The Debian package manager command, dpkg ,
     consists of an
action
that specifies a
     major mode of operation as well as zero or more
options
, which modify the action’s
     behavior.
    The dpkg command maintains package
     information in /var/lib/dpkg . There are two
     files that are of particular interest:
    available
The list of all available packages.
status
Contains package attributes, such as whether it is
     installed or marked for removal.
    These files are modified by dpkg,
     dselect , and apt-get , and it is
     unlikely that they will ever need to be