5.7. How do I tell what version of sed I am using?

Try entering "sed" all by itself on the command line, followed by no arguments or parameters. Also, try "sed --version". In a pinch, you can also try this:

       strings sed | grep -i ver

Your version of 'strings' must be a version of the Unix utility of this name. It should not be the DOS utility STRINGS.COM by Douglas Boling.