Troubleshooting Incorrect Output

If the printer and the print service software are not configured correctly, the printer might print, but it might provide output that is not what you expect.

Check the Printer Type and File Content Type

If you used the wrong printer type when you set up the printer with the LP print service, inappropriate printer control characters can be sent to the printer. The results are unpredictable: nothing might print, the output might be illegible, or the output might be printed in the wrong character set or font.

If you specified an incorrect file content type, the banner page might print, but that is all. The file content types specified for a printer indicate the types of files the printer can print directly, without filtering. When a user sends a file to the printer, the file is sent directly to the printer without any attempt to filter it. The problem occurs if the printer cannot handle the file content type.

When setting up print clients, you increase the chance for a mistake because the file content types must be correct on both the print server and the print client. If you set up the print client as recommended with any as the file content type, files are sent directly to the print server and the print server determines the need for filtering. Therefore, the file content types have to be specified correctly only on the server.

You can specify a file content on the print client to off-load filtering from the server to the client, but the content type must be supported on the print server.

Check the stty Settings

Many formatting problems can result when the default stty (standard terminal) settings do not match the settings required by the printer. The following sections describe what happens when some of the settings are incorrect.

Wrong Baud Settings

When the baud setting of the computer does not match the baud setting of the printer, usually you get some output, but it does not look like the file you submitted for printing. Random characters are displayed, with an unusual mixture of special characters and undesirable spacing. The default for the LP print service is 9600 baud.

If a printer is connected by a parallel port, the baud setting is irrelevant.

Wrong Parity Setting

Some printers use a parity bit to ensure that data received for printing has not been garbled during transmission. The parity bit setting for the computer and the printer must match. If they do not match, some characters either will not be printed at all, or will be replaced by other characters. In this case, the output looks approximately correct. The word spacing is all right and many letters are in their correct place. The LP print service does not set the parity bit by default.

Wrong Tab Settings

If the file contains tabs, but the printer expects no tabs, the printed output might contain the complete contents of the file, but the text might be jammed against the right margin. Also, if the tab settings for the printer are incorrect, the text might not have a left margin, it might run together, it might be concentrated to a portion of the page, or it might be incorrectly double-spaced. The default is for tabs to be set every eight spaces.

Wrong Return Setting

If the output is double-spaced, but it should be single-spaced, either the tab settings for the printer are incorrect or the printer is adding a line feed after each return. The LP print service adds a return before each line feed, so the combination causes two line feeds.

If the print zigzags down the page, the stty option onlcr that sends a return before every line feed is not set. The stty=onlcr option is set by default, but you might have cleared it while trying to solve other printing problems.