<para>This chapter gives you some hints about further configuration possibilities which may not be available through the &tdeprint; &GUI; interface to &CUPS;.</para>
<para>A lot of information about the inner workings of &CUPS; is available through the web interface, which &CUPS; will always support. It works with any browser (yes, even text-based ones). Just go to <ulink url="http://localhost:631/">http://localhost:631/</ulink> for a start. There you find a link to locally available &CUPS; documentation in <acronym>HTML</acronym> and <acronym>PDF</acronym> if you are new to &CUPS;.</para>
<para>&CUPS; is accessible through other means than &tdeprint;: commandline and browser are two native &CUPS; interfaces. The many commandline utilities add up to the most complete control you have on &CUPS;. The web interface is only a subset of all available configuration or control options. </para>
<para>This is also true for &tdeprint;. Generally, as &CUPS; develops, most new features will first be implemented through the commandline. Be sure to check the latest versions of the man pages for &CUPS; to stay up-to-date with new features after you install a new version.</para>
<para>Depending on your update method for &CUPS;, your active configuration file might not have been re-placed by a new one; thus your new, more capable &CUPS;-daemon might not have been told by the old configuration file about the new features to use.</para>
<para>A complete list of available files and man pages should always be in the &CUPS; Software Administrator Manual (<ulink url="http://localhost:631/sam.html#FILES">http://localhost:631/sam.html#FILES</ulink>. In the &konqueror; &URL;/location field, type <userinput>man:/lpadmin</userinput> and <userinput>man:/cupsd.conf</userinput> to find out about the most important command and configuration file. You knew already about &konqueror;'s nice abilities to show you the traditional &UNIX; man pages, didn't you? Read this. From there you find more interesting hints and links to other man pages and documentation.</para>
<title>Allowing or denying printer access for certain users</title>
<para>When installing (or modifying) a printer through the command line, you can either deny or allow the usage of that printer to certain users:</para>
<para>will allow the usage of this (believe me: very nice and also very professional) printer to only the three mentioned users and at the same time deny it to all others. If another user wants to print on the DigiMaster via this &CUPS; server, he will receive an error message along the lines <errortype>client-error-not-possible</errortype>.</para>
<para>will deny the usage of this same printer to the three mentioned users and at the same time allow it to all others. If <quote>denied</quote> user wants to print on the DigiMaster via this &CUPS; server, he will receive an error message along the lines <errortype>client-error-not-possible</errortype>.</para>
<para>Only one of the two options may be used at one time; at present there is no support to have a similar option in a per-group based way. This will be implemented in the future.</para>
<para>Sometimes you want to impose quotas for certain printers. With quotas you can set upper limits for the number of pages or the amount of data to be printed over a certain period to a certain printer.</para>
<para>Quotas can be set with the <option>-o</option> option when installing a printer with the <command>lpadmin</command> command, or afterwards for an already existing printer. Following are some guidelines (which are missing at the time of writing in the, official &CUPS; documentation):</para>
<para>This means: you can limit every user to 20 pages per day on an expensive printer, but you cannot limit every user except <systemitem class="username">Kurt</systemitem> or <systemitem class="username">root</systemitem>.</para>
<para>There are <option>job-k-limit</option>, <option>job-page-limit</option>, and <option>job-quota-period</option> options to give when setting up a printer.</para>
<para><option>job-quota-period</option> sets a time interval for quota computing (intervals are determined in seconds; so a day is 60x60x24=86.400, a week is 60x60x24x7=604,800, and a month is 60x60x24x30=2.592.000 seconds.)</para>
<para>The default value of 0 for <option>job-quota-period</option> specifies that the limits apply to all jobs that have been printed by a user that are still known to the system.</para>
<para>This sets a limit of a file size of 1 MB (in total) for each user of existing printer <systemitem class="resource">danka_infotec_4850</systemitem> during one week.</para>
<para>This sets a limit of 100 pages (in total) for each user of existing printer <systemitem class="resource">danka_infotec_4105</systemitem> during one week.</para>
<para>This sets a combined limit of 1 MB (in total) and 100 pages (in total) for each user of existing printer <systemitem class="resource">danka_infotec_P450</systemitem> during one week. Whichever limit is reached first will take effect.</para>
<title>Installing a <quote>raw</quote> printer</title>
<para>There are different ways to define a <quote>raw</quote> printer. One comfortable one is to use the <command>lpadmin</command> command. Just don't define a &PPD; file to be used for that printer and it will be a raw one:</para>
<para>Raw printer queues are those which don't touch the print file to transform it to a different file format. You need this for example when printing from &Windows; clients via Samba through a &CUPS; server to a <acronym>PCL</acronym> printer: in this case the &Windows; side printer driver would generate the finished print file format for the target printer and filtering it through &CUPS; filters would only harm the purpose. Under certain circumstances (if you want to make sure that the file goes to the printer <quote>unfiltered</quote> by &CUPS;) the <quote><command>lpadmin</command> without a &PPD;</quote> comes in handy.</para>
<para>The user tried to access a nonexistent resource on the &CUPS; server, such as trying to print a nonexistent file, or one that you are denied permission to read.</para>
<para>To be able to re-start your <quote>completed</quote> jobs from the web interface, you need a setting in the <filename>/etc/cups/cupsd.conf</filename> file: set <userinput>PreserveJobFiles True</userinput>.</para>
<para>&CUPS; does the <quote>print accounting</quote> by passing nearly every job through the <quote>pstops</quote> filter. This one does, amongst other things, the page counting. Output of this filter there may be piped into other filters (like pstoraster --> rastertopcl) or sent to the printer directly (if it is a &PostScript; printer).</para>
<para>In any case, this works for network, parallel, serial or <acronym>USB</acronym> printers the same. For pstops to work, it needs <acronym>DSC</acronym>, Document Structuring Convention compliant &PostScript; (or near-equivalent) as input. So it calculates the pages during filtering on the print server and writes info about every single page (what time, which user, which job-ID and -name, which printer, how many copies of which pages of the document, how many kilo-bytes?) into <filename>/var/log/cups/page_log</filename>.</para>
<para>By the way: on my personal <quote>wishlist</quote> is a hack of <quote>webalizer</quote> to read and analyse the page_log and give a similar output. Anyone?</para>
<para>However, it is <emphasis>not</emphasis> giving correct results in the following cases:</para>
<para>The printer jams and maybe therefore throw away the job (real live experience; or maybe throwing away the job because of problems with the data format)</para>
<para>Therefore the page accounting of &CUPS; is <quote>only</quote> an approximation (in many cases an excellent or at least good one, in others a quite poor one). The only reliable print count is the one done by the internal printer counter. (Because this is the one you pay for, if you are on a <quote>click price</quote> or similar.) Some, by far not most, printers can be queried remotely for that information via <acronym>SNMP</acronym> (Simple Network Management Protocol). That means, in a bigger network with many different printers there <emphasis>is</emphasis> just no completely reliable and accurate page accounting tool!</para>
<para>From &Windows; clients jobs nearly always need to be sent as <quote>raw</quote>. Why? If &CUPS; works as a print server for &Windows; clients using the original native &Windows; driver for the target print device, this guarantees the correct formatting of the job on the clients already; therefor the server should not touch it and print <quote>raw</quote>; therefor no filtering is started (and this is not even possible as the input from the clients is not &PostScript; as pstops expects; hence no page-count other than the default <quote>1</quote>.</para>
<para>See the man page for the <command>lpoptions</command> command. You may investigate a &CUPS;-enabled box about any option of its available printers. There is no need to have the printer installed locally. As long as the printer is available locally (through the &CUPS; <quote>printer browsing</quote> feature), it will also work remote.</para>
<para>To query for a printers' option typing <userinput><command>lpoptions</command> <option>-p</option> <parameter>HitachiDDP70MicroPress</parameter> <option>-l</option></userinput> will give a long listing of all available options as read from the &PPD; file for the given Hitachi-Printer (in my case installed on remote server transmeta). Remote server <systemitem class="systemname">Transmeta</systemitem> and its &CUPS; daemon as well as the localhost's &CUPS; daemon need to be up and running for this to succeed.</para>
<para>You know that for &PostScript; printer manufacturers it is <quote>legal</quote> to define their own internal names and procedures even for standard &PostScript; options. As long as the driver is able to retrieve the option from the &PPD; and show it to the user in a way that he understands it everything is OK. But what do <emphasis>you</emphasis> do, if you want to use some obscure printer options on the command line? How do you find out its exact syntax?</para>
<para>Let's take an example. Looking at Hitachi's DDP70 printer and how it implements duplex printing is revealing somehow. How do you tell how to print double sided? duplex or Duplex? Or another name altogether?.</para>
<para>Use the <command>lphelp</command> command which may be installed on your system locally. There is not yet a man page for <command>lphelp</command>.</para>
<para>This lists the available options for the named printer. It is nicely formatted and does explain every available option and how to use it. You can query different printers' options at once:</para>
<para>The printer names used in &CUPS; shall start with a letter and may contain up to 128 letters, numbers or underscores. Using dashes may lead to problems. Speaking about naming: printer names in &CUPS; are not case sensitive. So a printer named <systemitem class="resource">Best_of_Danka</systemitem> will be the same as <systemitem class="resource">best_of_danka</systemitem> or <systemitem class="resource">BEST_OF_DANKA</systemitem>. (This is a requirement of &IPP;, which &CUPS; is fully compliant with).</para>
<para>My files for printer <systemitem class="resource">lp</systemitem> sometimes mysteriously disappear and two days later I am told they got printed on a printer three floors below my office. What is going on?</para>
<para>Believe me, it is very unlikely that your printer is the only one with the name <systemitem class="resource">lp</systemitem>. Maybe &CUPS; is playing a trick on you. As you might have the setting <quote>ImplicitClasses On</quote> activated, &CUPS; tries to stuff all printers it sees on the network into a <quote>Class</quote> name lp. All jobs destined to lp are sent to this class and the first available member prints it. So if you had this nice fellow (who listened closely when you raved about &CUPS; and &tdeprint;) install &CUPS; and poke around the system...get the idea?</para>
<para>Take my advice: choose a unique name for any network printer! (Mind you, the one on your parallel port also turns out to be a network printer for the rest of the world if you don't take care of your settings).</para>
