Changing .zoo archive to .lzh archive: help!

[Dave P. Schaumann]

I am trying to write a script that will allow me to convert zoo archives
to lharc archives under Unix.  Here's what I have so far:

mkdir xxx
cd xxx
zoo xq// ../$1.zoo
lharc aq ../$1.lzh * `no-dot .*`
cd ..
rm -r xxx

Where "no-dot" is a simple program that echos back everything in argv[] that
isn't "." or ".."

This works fine, except for two problems: first, there might already be a
file called "xxx" in the current directory, and second, I can't have more
than one invocation going at once.

Now, I could write a program to generate a temporary directory name using
getpid() and some unlikely template, like "xx-######-temp".  What I need to
know is:

  1.  Is it a reasonable assumption that no two concurrent getpid()'s will
      return the same value?

  2.  Is there a better way to do this?

Thanks in advance for all replies.

-- 
Dave Schaumann      | DANGER: Access holes may tear easily.  Use of the access
		    | holes for lifting or carrying may result in damage to the
dave at cs.arizona.edu | carton and subsequent injury to the user.