The checkdigest script is an implementation extension verification hook. swverify will execute it
after verifying the GPG signature and swverify exits with its exit status. It is intended
to be a shell script that verifies the unpacked archive using existing GNU tools using the techniques described in
the next section "Verifying Using Existing GNU Tools".
The file checkdigest.sh from the swbis distribution will work for any package.
To include a checkdigest script in the package,
add the following line to the distribution object in the PSF.
checkdigest </usr/local/opt/src/checkdigest.sh # For Example