# usage: stack_trap arg sigspec
#
# stack_trap() behaves like bash's built-in trap, except that it "stacks" the
-# command ``arg`` on top of previously defined commands for ``sigspec`` instead
+# command "arg" on top of previously defined commands for "sigspec" instead
# of overwriting them.
# stacked traps are executed in reverse order of their registration
#
stack_trap()
{
local arg="$1"
- local sigspec="$2"
+ local sigspec="${2:-EXIT}"
# Use "trap -p" to get the quoting right
local old_trap="$(trap -p "$sigspec")"