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[;1m exit(Reason)[0m
Raises an exception of class [;;4mexit[0m with exit reason [;;4mReason[0m.
As evaluating this function causes an exception to be raised, it
has no return value.
The intent of the exception class [;;4mexit[0m is that the current
process should be stopped (for example when a message telling a
process to stop is received).
This function differ from [;;4merror/1,2,3[0m by causing an exception of
a different class and by having a reason that does not include the
list of functions from the call stack.
See the guide about errors and error handling for additional
information.
Example:
> exit(foobar).
** exception exit: foobar
> catch exit(foobar).
{'EXIT',foobar}
[;;4mNote[0m
If a process calls [;;4mexit(kill)[0m and does not catch the
exception, it will terminate with exit reason [;;4mkill[0m and also
emit exit signals with exit reason [;;4mkill[0m (not [;;4mkilled[0m) to
all linked processes. Such exit signals with exit reason [;;4mkill[0m
can be trapped by the linked processes. Note that this means
that signals with exit reason [;;4mkill[0m behave differently
depending on how they are sent because the signal will be
untrappable if a process sends such a signal to another
process with [;;4merlang:exit/2[0m.
[;1m exit(Pid, Reason)[0m
Sends an exit signal with exit reason [;;4mReason[0m to the process or
port identified by [;;4mPid[0m.
The following behavior applies if [;;4mReason[0m is any term, except [;;4m[0m
[;;4mnormal[0m or [;;4mkill[0m, and [;;4mP[0m is the process or port identified by [;;4m[0m
[;;4mPid[0m:
• If [;;4mP[0m is not trapping exits, [;;4mP[0m exits with exit reason [;;4m[0m
[;;4mReason[0m.
• If [;;4mP[0m is trapping exits, the exit signal is transformed
into a message [;;4m{'EXIT', From, Reason}[0m, where [;;4mFrom[0m is the
process identifier of the process that sent the exit signal,
and delivered to the message queue of [;;4mP[0m.
The following behavior applies if [;;4mReason[0m is the term [;;4mnormal[0m
and [;;4mPid[0m is the identifier of a process [;;4mP[0m which is not the same
as the process that invoked [;;4merlang:exit(Pid, normal)[0m (the
behavior when a process sends a signal with the [;;4mnormal[0m reason to
itself is described in the warning):
• If [;;4mP[0m is trapping exits, the exit signal is transformed
into a message [;;4m{'EXIT', From, normal}[0m, where [;;4mFrom[0m is the
process identifier of the process that sent the exit signal,
and delivered to [;;4mP[0m's message queue.
• The signal has no effect if [;;4mP[0m is not trapping exits.
If [;;4mReason[0m is the atom [;;4mkill[0m, that is, if [;;4mexit(Pid, kill)[0m is
called, an untrappable exit signal is sent to the process that is
identified by [;;4mPid[0m, which unconditionally exits with exit reason [;;4m[0m
[;;4mkilled[0m. The exit reason is changed from [;;4mkill[0m to [;;4mkilled[0m to
hint to linked processes that the killed process got killed by a
call to [;;4mexit(Pid, kill)[0m.
[;;4mNote[0m
The functions [;;4merlang:exit/1[0m and [;;4merlang:exit/2[0m are named
similarly but provide very different functionalities. The [;;4m[0m
[;;4merlang:exit/1[0m function should be used when the intent is to
stop the current process while [;;4merlang:exit/2[0m should be used
when the intent is to send an exit signal to another process.
Note also that [;;4merlang:exit/1[0m raises an exception that can be
caught while [;;4merlang:exit/2[0m does not cause any exception to
be raised.
[;;4mWarning[0m
The only scenario that has not been covered by the description
above is when a process [;;4mP[0m sends an exit signal with reason [;;4m[0m
[;;4mnormal[0m to itself, that is [;;4merlang:exit(self(), normal)[0m. The
behavior in this scenario is as follows:
• If [;;4mP[0m is trapping exits, the exit signal is transformed
into a message [;;4m{'EXIT', From, normal}[0m, where [;;4mFrom[0m is [;;4m[0m
[;;4mP[0m's process identifier, and delivered to [;;4mP[0m's message
queue.
• [;;4mP[0m exits with reason [;;4mnormal[0m if [;;4mP[0m is not trapping
exits. Note that the behavior described above is
different from when a process sends an exit signal with
reason [;;4mnormal[0m to another process. This is arguably
strange but this behavior is kept for backward
compatibility reasons.
[;;4mNote[0m
For some important information about distributed signals, see
the Blocking Signaling Over Distribution section in the
Processes chapter of the Erlang Reference Manual.
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