Shell options (non-portable extensions)

[magicant]

• errexit
  • Exit on double bracket command returning non-zero exit status
• xtrace
  • Disable recursive trace while expanding $PS4
  • Provide source information to the parse of $PS4
  • Support $YASH_PS4 and $YASH_PS4S
• Option to toggle POSIX conformance
  • For historical reasons, this option is named posixlycorrect, which may not describe its exact behavior.
  • 🤔 Should we split the option into the following two?
    1. Disable non-portable aspects
       • The shell rejects or warns about scripts that may behave differently on other POSIX-compliant shells.
    2. Disable non-conforming behaviors
       • The shell changes the behavior so it conforms to POSIX.
• Other non-portable options (details TBD...)

For portable options, see #209.