Basically, all you need is a working powerd binary, usually found in /sbin/powerd. This is usually part of the SysVinit package. As far as I know, all current Linux distributions include a recent version of SysVinit. Very old versions didn't include powerd.
The only problem you might have is that your cable might not match how powerd is set up, in which case you'll have to either rewire your cable, or pick up a copy of powerd.c and modify it to work with your cable. Or, for that matter, you can always pick up one of the following packages, most of which allow you to configure them to match your cable.
As mentioned, an alternative to using the powerd that comes with the SysVinit package would be to use one of the UPS packages now available. There are many packages currently available to aid in setting up computer/ups communications. None of this was available when I first wrote this Howto, which is why I had to write it. In fact, there's a good chance that you might be able to use one of these software packages, and avoid this Howto entirely!
As of 15 March 1997 or so, Sunsite's UPS directory had quite a few packages available. Other sites seem to have UPS control packages available too. Here's what I've found to date (all but two from sunsite):
A package for controlling APC Smart UPSs. Seems to basically follow the BUPS Howto (included here), but also seems to have some low battery warning support.
The .lsm file says that it's formerly the above package, but it actually includes the above package as a .tar.gz file inside of this tar.gz file! The documentation is spotty. It seems to support APC UPSs in both smart mode and dumb mode, but I can't be sure.
Another package for controlling APC Smart UPSs. Seems to include some sort of master/slave support (i.e. - one machine signals others to shut down when the power goes out). Seems to use the UPS in smart mode, as opposed to via modem signal line toggling.
The author ( ) writes:
smupsd monitors an APC Smart-UPS[TM] under Red Hat[TM] Linux. Should power fail, smupsd will power down the system and the UPS in an orderly fashion.
smupsd has the following features:
/etc/hosts.allow file.A general UPS handling package. Includes configurations for many UPSs - two TrippLite configurations, and three APC configurations. Includes good documentation. A best buy.
A replacement for the powerd that comes with the SysVinit package. As opposed to comments included in the documentation it doesn't seem to have been merged into the SysVinit package as of version 2.62. Its advantages are that it can act as a server for other powerds running on other machines (for when you have a network of machines hanging off a single UPS), and it can be configured by config file - the source code doesn't have to be edited and recompiled.
Another replacement for powerd. Seems to be quite comparable in features to powerd-2.0.tar.gz.
This package is for controlling Best UPSs. It's direct from Best's web site. Includes binaries for lots of unix flavors, but more importantly, it includes source code, so you can try it out under Linux, and if it doesn't work, you can try to fix it. The source code includes both ``basic checkups'' which controls the UPS in dumb mode, and ``advanced checkups'' which is a little more sophisticated - it will signal a shutdown when the UPS says it has X minutes of power remaining instead of just shutting down X minutes after the power goes out. The advanced checkups program also will shut down when the UPS registers various alarms such as High Ambient Temperature, Near Low Battery, Low AC Out, or User Test Alarm.
A package that might very well be on sunsite by the time you read this. It's a pair of communications module which works with Best Ferrups UPSs. It operates the UPS in smart mode. It inter-operates well with powerd-2.0 - useful if you have a big Best Ferrups UPS keeping up all the machines on a network.
NOTE - This package has yet to be uploaded to Sunsite. I keep begging the author to finish and upload it, but he has yet to find the time.
Deltec Electronics (and Exide) sell a software package called LanSafe III. They have a Linux version. It comes with their UPSs. They also say that it works with other UPSs (on the dumb level).
The author ( ) writes:
apcupsd-2.1.tar.gz replaces Enhanced-APC-UPSD.tar.gz
It is a very complete package for APC UPSs. There is support for the entire range of UPSs in their product line. I have now added smart mode signaling to the package and support with APC's own cables or a custom cable if you don't have an APC cable that is supported to date.
From the LSM:
A powerd and an X11 graphing utility which shows you the voltages, frequencies, load percentage and battery level in realtime. The protocol that the "Safeware" software uses, and "Tripplite" UPSs are supported. Source + ELF binaries.
From the LSM:
Program to interact with battery backups (Powerbox UPS).
From the LSM:
usvd is a daemon that monitors the state of an uninterrupted power supply and reacts upon state changes (line fail, line back, battery low situations). You can write your own scripts that are called in these cases. It does *not* require SYSVINIT.
Note that I've only glanced at these packages. I haven't used them. We were just about to start using bestups-0.9.tar.gz in conjunction with powerd-2.0.tar.gz, but we never quite got around to it.