linux

Maybe this will save somebody else some time, because I just spend about 3 hours banging my head against the wall on it.

If you’re getting a “550-Sender verify failed” error when Monit starts because its trying to send you an email via SMTP to let you know it’s started (or if you’re getting that error for just about any other reason), make sure that the email address that the message is being sent “from” actually exists.

If “monit@yourhostname.com” doesn’t exist, your SMTP server will likely reject the message and cause you all sorts of trouble.

Yeah, that hurt. Well, everything seems to be working again…

For the longest time I avoided using ACPI for power management on my Thinkpad X31 (instead I stuck with APM) because I could never get all the little hacks lined up properly. ACPI, since it is done primarily in hardware, requires a lot of tricks to get your machine to suspend and resume properly. Switching out of X, turning off LCD backlights, resetting graphics cards, etc etc. Its a real hassle.

However, if you’re fortunate enough to be running Debian Linux, you can install the “hibernate” package. Hibernate is basically sophisticated Bash script with pluggable options for all the most common ACPI hacks. I had ACPI up and running within minutes.

If you’ve got a Thinkpad X31 or similar machine, feel free to download my hibernate.conf and tweak it to your purposes. The only additions beyond a fairly standard hibernate configuration I had to make were adding hooks to turn the Radeon backlight on and off.

Some Debian developer will probably see this and yell at me for doing something very evil, but I find this trick quite useful and thought I’d share it with the world. You might notice I also made use of it in my Debian Java mini-howto.

The Debian “alternatives” system is basically a set of utilities designed for manipulating what is no more than a complex collection of symlinks. However, the flexibility it affords users is wonderful. It allows the administrator to set up intelligent “default versions” for system utilities such as editors, pagers, and terminals.

And it also, if you abuse it slightly, gives you an easy way to manage applications installed into /opt.

Debian, as you might know, isn’t that great at always packaging applications that don’t agree with its “social contract”. So you’ll usually find yourself jumping through hoops to get anything that involves Java installed. I install apps like Eclipse, Azureus, and VMWare into directories in /opt (/opt/eclipse, /opt/azureus, etc). And then I use update-alternatives to add intelligent symlinks back into the main system:

update-alternatives --verbose --install [desired symlink] [name] [executable location in /opt/whatever] 500

For a specific example: update-alternatives --verbose --install /usr/bin/vmware vmware /opt/vmware/bin/vmware 500

If you also want to install a link for the manpage, you can also do that:

update-alternatives --verbose --install /usr/bin/vmware vmware /opt/vmware/bin/vmware 500 --slave /usr/share/man/man1/vmware.1 vmware.1 /opt/vmware/man/man1/vmware.1

(I know that actually points to the manpage of the vmware XF86 driver, but you get the idea…)

And since all the links are tracked by update-alternatives, I can easily remove them when I uninstall the application: update-alternatives --remove-all vmware

Every time I set up a new system I have to figure out how to do this again, so I decided to post instructions for my benefit and for the benefit of those who might also be having problems with this.

Debian’s “Social Contract” forbids it from distributing “non-free” code as official packages. Thus, Sun’s version of Java is not in any of the official mirrors. You can sometimes find third-party packages from Blackdown and other groups, but they are often out of date and annoying. I prefer to get my Java directly from Sun.

I install my JDKs into /opt and use “dummy packages” to let Debian know that I really do have Java installed. That way I can install Debian packages requiring Java to be installed and everything will go smoothly.

This mini-HowTo assumes that you’re running Debian Unstable (Sid), but it should also work if you’re using Testing or even Ubuntu. It also assumes you’re doing all these steps as root.

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