uring the shadow.

<A NAME="lbAH">&nbsp;</A>
<H2>EXIT STATUS</H2>

<B>ppmshadow</B> returns status 0 if processing was completed without
errors, and a nonzero Unix error code if an error prevented generation
of output.  Some errors may result in the script aborting, usually
displaying error messages from various Netpbm components it uses,
without returning a nonzero error code.  When this happens, the output
file will be empty, so be sure to test this if you need to know if the
program succeeded. 

<A NAME=