如果使用双引号，还必须转义内部"引号:

If you use double quotes, you also have to escape "inner" quotes:

set x "Use \[slot/port] or \[\"portname\"] or \[slot/*] or \[*]."

或者使用大括号避免完全转义

Or use braces and avoid escaping altogether

set x {Use [slot/port] or ["portname"] or [slot/*] or [*].}

参见Tcl 的 12 条语法规则，数字 4 和 6

See Tcl's 12 syntax rules, numbers 4 and 6