There’s a very clever syntax in bash (and several other unix shells) that allows the output / input for subcommands to be hooked together.
http://tldp.org/LDP/abs/html/process-sub.html
This can be used to secure mysql passwords in scripts. e.g.
mysql --defaults-file=<(
printf '[client]\npassword=%s\n' xxxPASSWORDHERExxx
) -u xxxUSERNAMEHERExxx
Yes, be fascinated by non-standard Bourne shell syntax as the Bash shell slowly de-evolves into a PERL like monstrosity.