script to extract entityIDs

[Tom Scavo]

I'm preparing a contribution to the community that probes for
Shibboleth IdP V2 deployments. There's one missing piece in the
distribution:

Write a script that extracts the IdP entityIDs from a mixed metadata
file (i.e., a file of IdPs and SPs). The only requirements are:

1) must be reasonably fast
2) must run on either Linux or MAC OS (or preferably both)
3) must not require a 3rd-party software install

I have a bash script that does this but it's abysmally slow. I'm sure
someone can do better...

Thanks in advance,

Tom