-v Assignment --set Assignment --variable Assignment
-v assignment --set assignment --variable assignment
performs a variable assignment, like the \set
internal command.
Note: You must separate name and value, if any, by an equals sign (=) on the command line.
To unset a variable, omit the equal sign. To set a variable without a value, use the equals sign but omit the value. Make these assignments at a very early stage of start-up, so that variables reserved for internal purposes can get overwritten later.