UNDEF
Undefine previously defined macros.
SYNOPSIS
undef [ macro_name ]
DESCRIPTION
The undef command can be used to turn off previously defined macro. macro_name and its expansion are deleted from the macro table. This command is similar to the csh(1) unalias command.
BUGS
The command is open to macro substitution. The sequence:
define macro this is a macro
undef macro
will attempt to undefine the macro "this". To be able to undefine any macro, the % must be the first character on the line.
SEE ALSO
The define command.