The openssl command (several of its subcommands, including openssl x509) is polite with its data stream: once it read data, it didn't read more than it needed. This allows to chain multiple openssl commands like this:

while openssl x509 -noout -text; do :; done < cert-bundle.pem 

This will display all bundled certs in the file cert-bundle.pem (and end with an error: when there's no more input available, but that's just to show how it's working).

The openssl command (specifically, its openssl x509 subcommand, among others) is polite with its data stream: once it reads data, it doesn't read more than it needs. 

This allows to chain multiple openssl commands like this:

while openssl x509 -noout -text; do :; done < cert-bundle.pem 

This will display all bundled certs in the file cert-bundle.pem (and end with an error: when there's no more input available, but that's just to show how it's working).