in reply to Suggest a mnemonic for piped open

Another way of thinking about it that might work for you.

Place an imaginary 'perl' the other side of the pipe from the command.

Then perl '| command' becomes: perl supplying input to the command.

And 'command |' perl becomes: the command suppying input to perl.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

The start of some sanity?

In Section Seekers of Perl Wisdom