This article is from a FAQ concerning SCO operating systems. While some of the information may be applicable to any OS, or any Unix or Linux OS, it may be specific to SCO Xenix, Open Desktop or Openserver.

There is lots of Linux, Mac OS X and general Unix info elsewhere on this site: Search this site is the best way to find anything.

Serial Communications and UUCP

I increased my window size and UUCP broke!

If your modem, or the modem on a remote site, has small data buffers, a large window size may cause the modem's buffers to overrun. If the site that broke polls your system, you may wish to create a separate copy of uucico with a smaller window size, and specify it as the login shell in /etc/passwd. If you are the polling site, you may have to restore your original uucico. Alternatively, you could try a window size of 4, then 5, then 6, then 7, and see at what point UUCP stops working. You will then know the maximum window size you can use. You may also wish to ask the sysadmin at the remote site if there is anything they can do, such as forcing flow control to be used on their modem, that may remedy the problem. You may, however, have no choice but to return to using a window size of 3. If you have a Telebit modem, see the notes below relating to Telebit modems.

Jump to Comments

Many of the products and books I review are things I purchased for my own use. Some were given to me specifically for the purpose of reviewing them. I resell or can earn commissions from the sale of some of these items. Links within these pages may be affiliate links that pay me for referring you to them. That's mostly insignificant amounts of money; whenever it is not I have made my relationship plain. I also may own stock in companies mentioned here. If you have any question, please do feel free to contact me.

Specific links that take you to pages that allow you to purchase the item I reviewed are very likely to pay me a commission. Many of the books I review were given to me by the publishers specifically for the purpose of writing a review. These gifts and referral fees do not affect my opinions; I often give bad reviews anyway.

We use Google third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.