set or unset options and positional parameters

-e     When this option is on, if a simple command fails for any of the reasons listed in Consequences of
       Shell  Errors or returns an exit status value >0, and is not part of the compound list following a
       while, until, or if keyword, and is not a part of an AND  or  OR  list,  and  is  not  a  pipeline
       preceded by the ! reserved word, then the shell shall immediately exit.

-u     The shell shall write a message to standard error when it tries to expand a variable that  is  not
       set and immediately exit. An interactive shell shall not exit.

-x     The  shell shall write to standard error a trace for each command after it expands the command and
       before it executes it. It is unspecified whether the command that turns tracing off is traced.

-o     Write the current settings of the options to standard output in an unspecified format.

+o     Write the current option settings to standard output in a format that is suitable for  reinput  to
       the shell as commands that achieve the same options settings.