Function: _def_echo
Class: default
Section: default
C-Name: sd_echo
Prototype:
Help:
Doc: this toggle is either 1 (on) or 0 (off). When \kbd{echo}
 mode is on, each command is reprinted before being executed. This can be
 useful when reading a file with the \b{r} or \kbd{read} commands. For
 example, it is turned on at the beginning of the test files used to check
 whether \kbd{gp} has been built correctly (see \b{e}).

 The default value is \kbd{0} (no echo).