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Complete Idiot's Guide to Linux
(Publisher: Macmillan Computer Publishing)
Author(s): Manuel Ricart
ISBN: 078971826x
Publication Date: 12/22/98

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Non-RPM Packages

Although RPM is great, there are times that the software you are to install won’t be in the form of an RPM package. FTP sites like http://sunsite.unc.edu/pub/Linux/ distributions/redhat/contrib/i386/ have tons of programs already packaged in RPM, so you should check there to see if what you need is already available in package format.

If it is not, more than likely it will be supplied in a tar or compressed tar file. Working with the tar program for backups is discussed in great detail in Chapter 19, “Backups: Safeguarding Your Work.” If you need to install a program that doesn’t come packaged in RPM format, it is a good idea to install this program into its own directory in the /opt directory. The /opt directory contains mostly third-party software, such as KDE, Netscape, and so on. To make the program visible to the shell, you can create a link for its executable file in the /opt/bin directory. If this directory doesn’t exist, you should create it and add it to your PATH environment variable.

Tar

To extract files from a tar file, follow these steps:

1.  Create a directory where you are going to put the files from the archive. It is possible that the tar file will scatter a number of files to the current directory, so it is always a good idea to create a new directory to receive the files.
2.  Move the tar archive to the destination directory.
3.  Put the Cd into the directory.
4.  Extract the file using tar: tar xvf afile.tar.

If the maker of the tar file was conscientious enough to place all the files into a directory, you are set. Sometimes the tar file will contain a file called install.sh or some other installation script. Follow instructions as per any readme files (view them with a page such as less).

UNIX Compressed Archives: Gzip and Compress

Many times tar files will be distributed in compressed format; the typical extensions for compressed files are .gz (gnu zip, or gzip), .Z for the compress program, and .zip for Windows zip compressed archives. If the file has a name like file.tar.gz, that file is a gnu zip compressed tar file. To extract it, you’ll have to specify the z option to tar:

     [alberto@digital /tmp]$ tar -xzvf file.tar.gz
     nsmail/
     nsmail/Drafts
     nsmail/.Drafts.summary
     nsmail/Trash
     nsmail/.Trash.summary
     nsmail/Sent
     nsmail/.Sent.summary
     nsmail/Unsent Messages
     nsmail/.Unsent Messages.summary
     nsmail/Inbox
     nsmail/.Inbox.summary

Another way of accomplishing the same task is to use pipes using the gzcat program (similar to cat). This program reads information in the compressed archive, decompresses it, and copies it out to the STDOUT. Here’s an example of how to use gzcat and tar together:

     gzcat file.tar.gz | tar -xf -

In this example, gzcat pipes the resulting output, a tar file, to the tar program. The tar program looks for data in its STDIN stream because the dash (-) is provided to the f option as an argument.

Another way is to decompress the gzip file and then use tar normally. This is more inefficient, and if you are short on disk space, it could cause you to run out of space:

     gunzip file.tar.gz; tar -xf file.tar

The gunzip, gzcat, and the z option to tar can handle files with the .gz or Z extension. If you find a really old archive, you might find it with a .z extension; this is also a gzip compressed file.

If the file is not compressed with tar, it just sports a .gz extension. You can use gunzip to decompress it, like this:

     gunzip file.gz

Windows Compressed Archives: Zip

The zip archive format (.zip) originally developed for DOS by Phil Katz is in use by virtually every Windows computer. Linux users can also extract and create this file format using the unzip and zip tools.

To unzip a file, just use the unzip command:

     [alberto@digital /tmp]$ unzip file.zip
     Archive:  file.zip
        creating: nsmail/
      extracting: nsmail/Drafts
       inflating: nsmail/.Drafts.summary
       inflating: nsmail/Trash
       inflating: nsmail/.Trash.summary
       inflating: nsmail/Sent
       inflating: nsmail/.Sent.summary
      extracting: nsmail/Unsent Messages
       inflating: nsmail/.Unsent Messages.summary
       inflating: nsmail/Inbox
       inflating: nsmail/.Inbox.summary


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