쉘프로그램상에서 SIG_IGN처럼 동작하게 하려면?

trap [-lp] [arg] [sigspec ...]
The command arg is to be read and executed when the shell
receives signal(s) sigspec. If arg is absent or -, all speci-
fied signals are reset to their original values (the values they
had upon entrance to the shell). If arg is the null string the
signal specified by each sigspec is ignored by the shell and by
the commands it invokes. If arg is not present and -p has been
supplied, then the trap commands associated with each sigspec
are displayed. If no arguments are supplied or if only -p is
given, trap prints the list of commands associated with each
signal number. Each sigspec is either a signal name defined in
<signal.h>, or a signal number. If a sigspec is EXIT (0) the
command arg is executed on exit from the shell. If a sigspec is
DEBUG, the command arg is executed after every simple command
(see SHELL GRAMMAR above). If a sigspec is ERR, the command arg
is executed whenever a simple command has a non-zero exit sta-
tus. The ERR trap is not executed if the failed command is part
of an until or while loop, part of an if statement, part of a &&
or ?귘봻 list, or if the command?셲 return value is being inverted
via !. The -l option causes the shell to print a list of signal
names and their corresponding numbers. Signals ignored upon
entry to the shell cannot be trapped or reset. Trapped signals
are reset to their original values in a child process when it is
created. The return status is false if any sigspec is invalid;
otherwise trap returns true.