UNIX Administratosphere

This credit card from the LinuxFund seems like a good idea.  You and I would certainly like to support open source projects like Linux and KDE and so on.  Each purchase on this credit card results in a donation to a worthy open source cause, and you can send all of your cash-back rewards back as donations as well.

However, this turns out to be a lesson in reading the fine print.  This card has some very ominous conditions, which they don’t tell you except in the fine print:

• The rate is not fixed, but variable: that means it can go up and down over time, with no changes in the terms.
• The terms (including APR, fees, and conditions) may be changed at any time and without notice to you.
• The default rate is (approximately) 12% over prime up to 21% over prime.
• Cash advances are 24% over prime.
• If you miss a payment by more than 15 days, your rate will skyrocket to 32% over prime.
• If you miss a payment by more than 5 days twice in a year, your rate will skyrocket to 32% over prime.
• If you miss any payment on any card you own they will raise your rate.

As you can see, there are a number of gotcha! features to this card.  However, it is not alone.  Here are some ways to avoid the gotchas:

• Is the advertized rate an introductory rate?  When does it expire?
• What is the rate for purchases?
• What is the rate for cash advances?
• Are there any other rates?
• Are the rates fixed or variable?
• Is there a grace period?  What happens if you miss a payment?
• Are the rates dependent on other cards?

It has been said that consumer credit is the riskiest form of credit, and the terms on most cards suggest that the credit card companies think so.  Read the fine print carefully!

In finding information about the dynamic loader and shared libraries in general, there are several places to look. The obvious Internet location is Google; however, the system itself has a lot of information about shared libraries if one only knows where to look.

The first place is the information on the dynamic loader’s man page. Unfortunately, most loaders have names that are unique among their UNIX peers (Linux is almost universal). You can start by looking at the /lib directory for a program containing the string “ld” (or perhaps, “dl”). On Linux, this produces:

# ls -d *ld*
ld-2.6.so ld-linux.so.2

The proper Linux loader is ld-linux.so.

On HP-UX, this produces:

# ls -d *ld*
dld.sl* libdld.2* libldap_send.1*
libdld.0@ libdld.sl@ libldap_send.sl@
libdld.1* libldap.sl@ libnss_ldap.1*

Here, the proper loader is dld.sl.

Looking at the man pages for ld-linux.so or dld.sl or whatever was found gives a vast amount of information directly related to the dynamic loader and how it loads shared libraries, as well as debugging tools to report on how the libraries are found and loaded.

This man page will also mention utilities that will help you manipulate shared libraries. For example, the Linux man page for ld-linux.so mentions ldconfig(8); the HP-UX man page for dld.sl mentions the utilities fastbind( and chatr(8).

There are other utilities that remain fairly generic and which can help, though these tend to be specific to machines that are configured for development. If the development tools are not loaded, these tools may be missing. These utilities may include:

• ldd - list libraries used by a binary
• nm - list symbols from program binaries and/or libraries
• objdump - display information from binaries and/or libraries
• readelf - display information from ELF-formatted binaries

Always look at the SEE ALSO section in order find more information.