2.1 Installing Perl

We described Perl's origins and advantages in Chapter 1. In this section, we'll describe the basics of the installation process for Perl. To obtain Perl and to get more detailed information about this process, check out these web sites:

http://www.perl.com

http://www.perl.org

Main Perl portals.

http://www.activestate.com

ActiveState Win32 Perl portal site. You'll find many other projects, including ActivePerl, under the main ActiveState portal; most ActiveState products tend to have fairly fluid web addresses, so we won't attempt to provide them here.

2.1.1 Installing Perl on Unix

There are three basic ways to get started with Perl on Unix and Linux systems, the third of which is best for reasons we'll explain shortly:

On most Unix versions, if you install Perl as the root user and accept the default installation directories, it will generally embed itself into either one of the following directories:

/usr/bin

/usr/local/bin

In most cases, this is fine; however, you may wish to install it somewhere else, such as /u01/app/perl.

There are several reasons why you might want to install Perl in a different location:

• If you're an Oracle DBA who is working on other people's systems, you may be denied access to the root user's system directories.

• You may have theoretical access, but jumping through the corporate hoops to get actual physical access on some production systems (and having to fill out all the necessary forms) may just not be worth it.

• Some versions of Perl, may already exist on your system and be used by everyone else. However, you want your own latest-and-greatest private Perl to do the work you need it to do, without upsetting the informational applecart. Those guys in marketing may be happy relying on that ancient Perl 4 workhorse, but we need something a bit more developed.

There are also several secondary reasons:

• Upgrading module versions, such as DBD::Oracle, when they become available, will be simpler if you're in complete control of the Perl installation location.

• Adding new modules also becomes easier if you don't need to ask people's permission to do it, or to work within their weekly downtime window (you can almost guarantee that window will be Wednesday morning at 3:00 AM).

• For similar reasons, upgrading Perl itself will also be painless. Your local neighborhood system administrators may even award you bonus points for keeping off their turf!

Although we'll assume in the following discussion that you're installing Perl in default locations as root (which is most often the case), we'll indicate the one place where you can change this default, if you want to install Perl under something more like the oracle or oramon user, in a nonstandard location.

This chapter assumes that you want to create your own version of Perl — one that is distinct from the Perl executables provided automatically in Oracle releases beginning with Version 8.1.7. (Later in this chapter, in Section 2.1.1.3 we'll explain why we recommend that you create your own version of Perl.) You need to be careful not to get these two versions of Perl confused (people installing Perl for the first time sometimes do this). One way to keep the versions straight is to ensure that your own independent version of Perl comes first in your system's generic PATH variable.

2.1.1.1 Finding Perl already installed on your system

If Perl exists somewhere on your system (i.e., the main perl executable program is available under your operating system, via the PATH environment variable), you can usually find it by running the following command:

$ perl -v

If you believe that Perl is on your machine, but this command fails to return anything, you may want to discover where Perl is living and then add it to your executables PATH. To find it, try one of the following commands:

$ type perl
$ which perl
$ whence perl
$ locate perl

If these fail to work, or if Perl is still unavailable on your flavor of Unix, try the ultimate blockbuster approach:

$ find / -name "perl*" -print 2>/dev/null

Click, whirr. Once you've found Perl, add its executable directory into your PATH and then run the perl -v command. What we're looking for is something like this:

$ perl -v
  
This is perl, v5.6.1 built for i686-linux
  
Copyright 1987-2001, Larry Wall
  
Perl may be copied only under the terms of either the Artistic License 
or the GNU General Public License, which may be found in the 
Perl 5 source kit.
  
Complete documentation for Perl, including FAQ lists, should be found 
On this system using `man perl' or `perldoc perl'.  If you have access 
to the Internet, point your browser at http://www.perl.com/, the Perl 
Home Page.
  
$

Most Linux machines (depending on the release date of the Linux distribution) have Perl already on them. If you find Perl 5.6, or above, that's good enough. For some bizarre reason, many proprietary versions of Unix fail to come presupplied with Perl, but that's OK. It's much more fun to install from source! We'll show you how shortly.

2.1.1.2 Installing Perl from a prebuilt package

Some Oracle DBAs running Unix systems choose to install Perl from a prebuilt executable binary. In general, we recommend against this approach. Even if this option is available to you, it has several disadvantages in comparison to building Perl from source, mainly because prebuilt binaries may not match the configuration of your local system — for example:

• They may implicitly point to libraries that are not available on the particular machine.

• The original compiler options with which the package was created may not be supported on your current system.

• They may assume default paths that don't exist. For example, most of the prebuilt Unix Perl packages assume that the main perl executable is going to live under /usr/local/bin. This is especially problematic if, as we mentioned earlier, write access is unavailable to these kinds of directories.

Building from source, as we describe in the next section, is the best way to overcome local difficulties of these kinds.

If you do need to go down the prepackaged route, for whatever reason, be aware that most proprietary Unixes do have some great freeware sites. Although we think Perl is best if built from source on Unix, you need to build it with compilers, and if you haven't got one, these sites and their packages are invaluable for providing you with prepackaged compilers such as gcc. Some of the best sites we've found are:

For Solaris

http://sunfreeware.com

For AIX

http://ftp.univie.ac.at/aix

ftp://aixpdslib.seas.ucla.edu/pub

For HP-UX

http://jazz.external.hp.com/src/index.html#perl

For IRIX

http://freeware.sgi.com/index.html

For OpenBSD

http://www.openbsd.org/ports.html

For Linux

Virtually every flavor of Linux also has its own home site, which is full of Unix freeware download opportunities. Here are just some of the possibilities:

http://www.redhat.com/apps/download/

http://www.suse.de/us/support/download/

http://www.linux-mandrake.com/en/ftp.php3

http://www.caldera.com/download/mirrors.html

http://www.debian.org/distrib/ftplist

http://www.turbolinux.com/download/

http://www.slackware.com/packages/

You'll find the appropriate installation instructions at each site, and a web search should uncover any others. Here we'll run through the typical steps for Solaris. These are only guidelines; be sure that you obtain, and read carefully, the most up-to-date installation information for your own platform.

For example, the following commands would install the standard Perl 5.6.1 package as the root user:

$ gzip -d perl-5.6.1-sol8-sparc-local.gz
$ pkgadd -d perl-5.6.1-sol8-sparc-local

These kinds of steps (as specified on the appropriate site FAQ or within any accompanying README files) will build a fully functioning Perl system for you, adding the Perl executable to a directory like /usr/local/bin/perl. You'll follow similar steps for most of the other Unixes.

Using some download browser screens, the prebuilt packages will occasionally download without the *.gz suffix. This confuses the gunzip program. If this problem occurs, you can solve it by simply renaming the downloaded file with the additional *.gz suffixed extension.

2.1.1.3 Installing Perl from source

This third option is the one we recommend for Unix. To use our PDBA Toolkit most effectively, we recommend that you install at least Perl 5.6 from source. It's true that you may have older versions of Perl on your system, or versions built from prepackaged executables. However, we need to lay a specific version of Perl DBI on top of Perl, and for that reason we must ensure that Perl 5.6 has been set up correctly for your machine. The best way of doing this is by building up from source.

2.1.1.3.1 Obtaining the required C compiler

You must have a C compiler before you can complete your Perl installation. Fortunately, Linux virtually always comes with a gcc C compiler already on board, and most proprietary Unix types often come with their own, which is usually called cc. Even if you already have a C compiler, though, you may want to get hold of gcc because most open source project installations are built and tested with it. Using gcc, rather than any other C compiler, automatically eliminates many compiler incompatibility problems.

The gcc compiler is the creation of the GNU project, which was started in 1984 by Richard M. Stallman with the goal of developing a completely free Unix-like operating system. This project culminated in the development of the various GNU/Linux operating systems, better known by their generic name "Linux" after their core kernel developed by Linus Torvalds. You can check out the GNU project's definition of the word "free," get information about gcc, and learn much more at:

http://www.gnu.org

Although gcc is usually the right choice, always read the appropriate README files within the stable.tar.gz Perl distribution for each operating system. For instance, here's what the README.aix file says about using gcc:

Perl can be compiled with either IBM's ANSI C compiler or with gcc. The former is recommended, as not only can it compile Perl with no difficulty, but also can take advantage of features listed later that require the use of IBM compiler-specific command-line flags.

With AIX, you may have difficulties unless you do use the proprietary cc compiler, as the note suggests. Most HP platforms are also better served with HP's "official" C compiler, which you may have to purchase as an extra-cost item.

If you enjoy a challenge, and you'd like to boot-strap gcc from its own source code using your own proprietary cc compiler as the bootstrapper, check out the GNU web site for details.

You won't need to compile gcc from source (unless you enjoy Catch-22-type challenges) because virtually every flavor of Unix has a gcc binary package built for it already by the open source community. You can get such packages from the freeware sites listed in the previous section.

For example, at the time this book went to press, the following sites contained the latest gcc package for three major commercial Unix flavors.

http://sunfreeware.com

For Solaris

http://ftp.univie.ac.at/aix/aix432

For AIX

http://jazz.external.hp.com/src/gnu/download2_95_2.html

For HP-UX

You'll find appropriate README installation instructions at each site. Here, we'll run through the typical steps for Solaris. These are only guidelines. Be sure you obtain the most up-to-date installation information for your own platform, from the site where you get the gcc package:

For example, if you're logged on as the root user, the following commands will install the gcc package:

# gzip -d gcc-3.0.3-sol8-sparc-local.gz
# pkgadd -d gcc-3.0.3-sol8-sparc-local

The actual executable will usually get dispatched to /usr/local/bin/gcc.

As a final compilation caveat, note that the default Perl installation process looks for a generic cc compiler, unless you alter this behavior by following the detailed instructions in the Perl INSTALL file. To make sure you still pick up gcc anyway, move your old cc compiler somewhere safe, such as cc.old, or place a new cc location higher up in your PATH. Now we symbolically link in the new cc file to point at the real gcc compiler, to achieve a situation similar to the following:

$ type cc
cc is /home/oracle/bin/cc
$ ls -l /home/oracle/bin/cc
/home/oracle/bin/cc -> gcc
$ type gcc
gcc is /usr/local/bin/gcc

2.1.1.3.2 Obtaining the source for Perl.

Once the compiler is ready, it's time to get the Perl source code itself. To obtain the latest version, visit CPAN, the Comprehensive Perl Archive Network:

http://www.perl.com/CPAN/README.html

This will probably direct you to download the most recent stable version of Perl — for example:

http://www.perl.com/CPAN-local/src/stable.tar.gz

Once you've obtained your own copy of stable.tar.gz, follow these basic steps to install Perl:

2.1.2 Installing Perl on Win32

For Win32, although you can build from source (if you have the relevant Win32 compilers, or you can use Cygwin (as described later in this chapter), most people use the prebuilt ActiveState binaries, and that's what we'll do here.

Follow these steps:

Because of the standard security architecture of Win32 systems, network shares and shared drives in a cluster are sometimes unavailable to the SYSTEM user. Therefore, any Perl scripts running from a scheduler or as a service will require that Perl be installed on a local drive. The C:\ drive is often a safe bet (this is generally the default), and this is where we always install Perl.

Figure 2-1. Installing ActivePerl

We hope you won't encounter any problems getting Perl installed. But if you do, and you can't get the necessary help from the README and INSTALL files or here in this book, go to the Perl information sources listed in Chapter 1.