Shell Programming and Scripting

How would I go about an error check within a script. For example, if I have a script that I know might contain an error with a certain command, is there a way to give an alternate command if the first fails?

The best way I can explain it, is from the Mac world, using Applescript. With AS, I can do something this:

try
do something
on error
do something else
end try

Is there a similar function for shell scripting?

Thanks!

Afaik, the shell interpreters don't offer exception handling
as you have quoted from AppleScript
(but then I don't know AppleScript).
You can however check a command's return code
which is captured in the special variable $?
An RC of 0 is considered successful execution,
and the shell's logic constructs evaluate a "true" condition
in that case,
which is a bit confusing if you are comming from other
programming languages.
In Perl scripting you would mimic exception handling
by putting "problematic" code in an eval block
and querying the Perl special variable $@ after it.