Olaf Kirch - Linux Network Administrator Guide, Second Edition

TEST AA02009E

Q2 EF0200D9

NPI223761_P1 DA03007C

Q1 F1060004

I-DATA 0D0A003B

NPI223761_P3 D80A0031

Our example shows a list of the print queues available to the guest user on the ALES_F1 fileserver. [88] It looks like the system administrators had been sampling some of the Virtual Brewery's wares before they chose some of those print queue names. Hopefully your print queue names are more meaningful!

To view the print jobs on a print queue, use the pqstat command. It takes the print queue name as an argument and lists all of the jobs in that queue. You may optionally supply another argument indicating how many of the jobs in the queue you'd like to list. The following sample output has been compressed a bit to fit the width of this book's page:

$ pqstat -S ALES_F1 NPI223761_P1

Server: ALES_F1 Queue: NPI223761_P1 Queue ID: 6A0E000C

Seq Name Description Status Form Job ID

------------------------------------------------------------------------

1 TOTRAN LyX document - proposal.lyx Active 0 02660001

We can see just one print job in the queue, owned by user TOTRAN. The rest of the options include a description of the job, its status, and its job identifier.

The pqrm command is used to remove print jobs from a specified print queue. To remove the job in the queue we've just obtained the status of, we'd use:

$ pqrm -S ALES_F1 NPI223761_P1 02660001

The command is pretty straightforward but is clumsy to use in a hurry. It would be a worthwhile project to write a basic script to simplify this operation.

There are two free software emulators for NetWare fileservers under Linux. lwared was developed by Ales Dryak and mars_nwe was developed by Martin Stover. Both of these packages provide elementary NetWare fileserver emulation under Linux, allowing NetWare clients to mount Linux directories exported as NetWare volumes. While the lwared server is simpler to configure, the mars_nwe server is more fully featured. The installation and configuration of these packages is beyond the scope of this chapter, but both are described in the IPX-HOWTO.

UUCP was designed in the late seventies by Mike Lesk at AT&T Bell Laboratories to provide a simple dialup network over public telephone lines. Despite the popularity of dialup PPP and SLIP connections to the Internet, many people who want to have email and Usenet News on their home machine still use UUCP because it is often cheaper, especially in countries where Internet users have to pay by the minute for local telephone calls, or where they do not have a local ISP and must pay long distance toll rates to connect. Although there are many implementations of UUCP running on a wide variety of hardware platforms and operating systems, overall, they are highly compatible.

However, as with most software that has somehow become "standard" over the years, there is no UUCP that one would call the UUCP. It has undergone a steady evolution since the first version was implemented in 1976. Currently, there are two major species that differ mainly in their hardware support and configuration. Of these two, various implementations exist, each varying slightly from its siblings.

One species is known as Version 2 UUCP, which dates back to a 1977 implementation by Mike Lesk, David A. Novitz, and Greg Chesson. Although it is fairly old, it is still frequently used. Recent implementations of Version 2 provide much of the comfort that the newer UUCP species do.

The second species was developed in 1983 and is commonly referred to as BNU (Basic Networking Utilities) or HoneyDanBer UUCP. The latter name is derived from the authors' names (P. Honeyman, D. A. Novitz, and B. E. Redman) and is often shortened further to HDB, which is the term we'll use in this chapter. HDB was conceived to eliminate some of Version 2 UUCP's deficiencies. For example, new transfer protocols were added, and the spool directory was split so that now there is one directory for each site with which you have UUCP traffic.

The implementation of UUCP currently distributed with Linux is Taylor UUCP 1.06, which is the version this chapter is based upon. [89] Written and copyrighted by Ian Taylor, 1995. Taylor UUCP Version 1.06 was released in August 1995. Apart from traditional configuration files, Taylor UUCP can also be compiled to understand the newstyle - a.k.a. Taylor - configuration files.

Taylor UUCP is usually compiled for HDB compatibility, the Taylor configuration scheme, or both. Because the Taylor scheme is much more flexible and probably easier to understand than the often obscure HDB configuration files, we will describe the Taylor scheme below.

This chapter is not designed to exhaustively describe the command-line options for the UUCP commands and what they do, but to give you an introduction to how to set up a working UUCP node. The first section gives a gentle introduction about how UUCP implements remote execution and file transfers. If you are not entirely new to UUCP, you might want to skip to the section "UUCP Configuration Files" later in this chapter, which explains the various files used to set up UUCP.

We will, however, assume that you are familiar with the user programs of the UUCP suite, uucp and uux. For a description, refer to the online manual pages.

Besides the publicly accessible programs uucp and uux, the UUCP suite contains a number of commands used for administrative purposes only. They are used to monitor UUCP traffic across your node, remove old log files, or compile statistics. None of these will be described here because they are peripheral to the main tasks of UUCP. Besides, they're well documented and fairly easy to understand; refer to the manual pages for more information. However, there is a third category, which comprise the actual UUCP "work horses." They are called uucico (where cico stands for copy-in copy-out), and uuxqt, which executes jobs sent from remote systems. We concentrate on these two important programs in this chapter.

If you're not satisfied with our coverage of these topics, you should read the documentation that comes with the UUCP package. This is a set of Texinfo files that describe the setup using the Taylor configuration scheme. You can convert the Texinfo files into a dvi file using the texi2dvi (found in the Texinfo package in your distribution) and view the dvi file using the xdvi command.

Guylhem Aznar's UUCP-HOWTO is another good source for information about UUCP in a Linux environment. It is available at any Linux Documentation Project mirror and is posted regularly to comp.os.linux.answers.

There's also a newsgroup for the discussion of UUCP called comp.mail.uucp. If you have questions specific to Taylor UUCP, you may be better off asking them there, rather than on the comp.os.linux.* groups.

The concept of jobs is vital to understanding UUCP. Every transfer that a user initiates with uucp or uux is called a job. It is made up of a command to be executed on a remote system, a collection of files to be transferred between sites, or both.

As an example, the following command makes UUCP copy the file netguide.ps to a remote host named pablo and execute the lpr command on pablo to print the file:

$ uux -r pablo!lpr!netguide.ps

UUCP does not generally call the remote system immediately to execute a job (or else you could make do with kermit). Instead, it temporarily stores the job description away. This is called spooling . The directory tree under which jobs are stored is therefore called the spool directory and is generally located in /var/spool/uucp . In our example, the job description would contain information about the remote command to be executed (lpr), the user who requested the execution, and a couple of other items. In addition to the job description, UUCP has to store the input file netguide.ps .