Re: Shell scripting in Bash

[Rob Browning <osiris@cs.utexas.edu>]

>>>>> "D" == Dale Scheetz <dwarf@polaris.net> writes:

D> I have been trying to learn shell scripting using the man page for
D> bash.  Asside from the need for a lot of reading between the lines,
D> there seem to be several errors. == is declared to be the equality
D> operator, but = is the correct syntax. || is declared to be the or
D> operator, but although:

D> What is the correct syntax for this kind of statement?

I think I see the source of your confusion.  As usual there is more
going on here than you thought.  First you have to realize that 

[ foo ] 

is a special construct in bash, which is just a synonym for 

test foo

So within the brackets, only the syntax that test can understand
applies.  See the bash man page for more details, but basically, test
uses = for equality, but in other places (arithmetic "lets" etc.)
bash uses == for equality (nice huh?).  Also, test doesn't understand
|| at all, instead it uses -o for or.  The || syntax is generally used
for linking commands like:

netscape || shutdown -h now 

<SARCASM INTENDED>

The test entry in the bash man page has a list of all the operators
that it can handle.

[Std disclaimer about personal conviction that perl is easier and
faster than the shell applies (of course there are good reasons to
ignore this disclaimer)]

Hope this helps,
--
Rob