Performing an Install

URLs — Another Way to Specify Package Files

If you've surfed the World Wide Web, you've no doubt noticed the way web pages are identified:

http://www.redhat.com/support/docs/rpm/RPM-HOWTO/RPM-HOWTO.html

This is called a Uniform Resource Locator, or URL. RPM can also use URLs, although they look a little bit different. Here's one:

ftp://ftp.redhat.com/pub/redhat/code/rpm/rpm-2.3-1.i386.rpm

The ftp: signifies that this URL is a File Transfer Protocol URL. As the name implies, this type of URL is used to move files around. The section containing ftp.redhat.com specifies the hostname, or the name of the system where the package file resides.

The remainder of the URL (/pub/redhat/code/rpm/rpm-2.3-1.i386.rpm) specifies the path to the package file, followed by the package file itself.

RPM's use of URLs gives us the ability to install a package located on the other side of the world, with a single command:

# rpm -i ftp://ftp.gnomovision.com/pub/rpms/foobar-1.0-1.i386.rpm #

This command would use anonymous FTP to obtain the foobar version 1.0 package file and install it on your system. Of course, anonymous FTP (no username and password required) is not always available. Therefore, the URL may also contain a username and password preceding the hostname:

ftp://smith:mypass@ftp.gnomovision.com/pub/rpms/foobar-1.0-1.i386.rpm

However, entering a password where it can be seen by anyone looking at your screen is a bad idea. So try this format:

ftp://smith@ftp.gnomovision.com/pub/rpms/foobar-1.0-1.i386.rpm

RPM will prompt you for your password, and you'll be in business:

# rpm -i ftp://smith@ftp.gnomovision.com/pub/rpms/apmd-2.4-1.i386.rpm Password for smith@ftp.gnomovision.com: mypass (not echoed) #

After entering a valid password, RPM installs the package.

On some systems, the FTP daemon doesn't run on the standard port 21. Normally this is done for the sake of enhanced security. Fortunately, there is a way to specify a non-standard port in a URL:

ftp://ftp.gnomovision.com:1024/pub/rpms/foobar-1.0-1.i386.rpm

This URL will direct the FTP request to port 1024. The --ftpport option is another way to specify the port. This option is discussed later, in the section called --ftpport <port>: Use <port> In FTP-based Installs.

A warning message you might never see

Depending on circumstances, the following message might be rare or very common. While performing an ordinary install, RPM prints a warning message:

# rpm -i cdp-0.33-100.i386.rpm warning: /etc/cdp-config saved as /etc/cdp-config.rpmorig #

What does it mean? It has to do with RPM's handling of config files. In the example above, RPM found a file (/etc/cdp-config) that didn't belong to any RPM-installed package. Since the cdp-0.33-100 package contains a file of the same name that is to be installed in the same directory, there is a problem.

RPM solves this the best way it can. It performs two steps:

1. It renames the original file to cdp-config.rpmorig.

2. It installs the new cdp-config file that came with the package.

Continuing our example, if we look in /etc, we see that this is exactly what has happened:

# ls -al /etc/cdp* -rw-r--r-- 1 root root 119 Jun 23 16:00 /etc/cdp-config -rw-rw-r-- 1 root root 56 Jun 14 21:44 /etc/cdp-config.rpmorig #

This is the best possible solution to a tricky problem. The package is installed with a config file that is known to work. After all, the original file may be for an older, incompatible version of the software. However, the original file is saved so that it can be studied by the system administrator, who can decide whether the original file should be put back into service or not.