Wednesday, July 25, 2007

Installing software under Linux

The installation of Linux as an operating system has become just as
easy as installing Windows. Where problems do turn up now and again,
however, is when it comes time to install individual programs. The
biggest problem is that there are no wizards to help users set up
software written for Linux.

Those who use the widely distributed SUSE Linux, though, do have use of
program called Yast2. It provides a convenient way to install software
- or delete it. The program offers a built-in search function that not
only lists software included in the Suse package by name, but also by
its function.

Installation of selected software often transpires much more simply
than under Windows, says Andrea Müller from the publishing house Linux
New Media in Munich.

"As soon as somebody highlights a program for installation, the package
manager automatically selects further software that is required for the
program to function properly," Müller says.

This process is known as resolving dependencies. Somewhat trickier is
later installation of Linux software downloaded from the Internet. "All
too often the packet manager reports that it cannot import the software
because other required files are missing," explains Müller, a Linux
expert.

Konquerer, an internet and file browser, can be used by users of the
KDE desktop interface to download and install software, reports Andreas
Jaeger, product leader for the Desktop system of SUSE Linux. A click on
the "Install program with Yast" option is sufficient, he claims. This
is only required if the program is not contained in the distribution's
CDs or DVDs.

Programs like Yast for Suse Linux or apt for Debian can be of service
if the software to be installed is available as so-called RPM or Debian
packages, respectively. The source can be a CD, DVD, or the internet.
APT (Advanced Package Tool) is another package management system for
software installation in Linux, explains Andreas Gebhard, Press
spokesman for the LinuxTag trade fair which is to be held from June 22
to 25 in Karlsruhe, Germany. "APT allows for very easy installation of
a program package or even an entire system," Gebhard says.

APT exists in both text-based console and graphical interface versions.
Like Yast, it automatically resolves dependencies.

Gebhard names Smart Package Manager, up2date for Red Hat and urpmi,
which is used with Mandrake Linux, as further installation tools that
offer a graphic front-end.

Yet new software often comes only as source text packets, packaged in
so-called tar.gz or tar.bz2 files. The user must then compile the
source text prior to the actual installation.

Compilation is the name of the process for turning source code written
in programming languages like C or C++ into binary code that the
computer can read and use.

Compilers, as the software that performs the task is known, come
bundled with all larger distributions. One frequently used version is
gcc. For all of this to happen, however, the so-called developer's
tools need to be installed along with the operating system. This can
also be done afterwards if it was forgotten during the initial
installation, however.

When manually installing Linux software, experts speak of the rule of
threes: this refers to three crucial installation commands
./configure@, make@, make install@. ./configure@ seeks out the files
needed for the installation. Problems often surface with this first
step, however, forcing the program to abort its work and display an
error message. "This is why you absolutely should take a look at the
Readme file before starting the installation," advises Andreas Jaeger.
Readme files offer details on peculiarities of the piece of software.

If a program required for the installation is missing, ./configure will
provide a message to that effect. In a crunch, the missing program can
be installed later using the package management. Make and make install
tend to produce relatively fewer problems. If make ends up aborting its
task, then a file may be missing. The error message should indicate the
source of the problem. Jaeger notes that the "rule of three" can often
lead to an incorrect selection of options. Beginners should use
finished packages, Mueller recommends.

Whether manually or automatic: If you have problems with an
installation, help can be found in the Linux user groups. Reading
through the pertinent Internet forums can also be helpful. Users can
also ask for help directly from the distributor, Andraes Gebhard
claims. "In many cases you're not the first one to stumble over a
specific problem."

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