ProcessSignal interface#

interface class ProcessSignal

On Posix systems, ProcessSignal is used to send a specific signal to a child process, see Process.kill.

Some ProcessSignals can also be watched, as a way to intercept the default signal handler and implement another. See ProcessSignal.watch for more information.

Properties#

hashCode no setter inherited#

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation

external int get hashCode;

name final#

final String name

The POSIX-standardized name of the signal e.g. ProcessSignal.name will be "SIGHUP" for ProcessSignal.sighup.

Implementation

final String name;

runtimeType no setter inherited#

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

signalNumber final#

final int signalNumber

The numeric constant for the signal e.g. ProcessSignal.signalNumber will be 1 for ProcessSignal.sighup on most platforms.

Implementation

final int signalNumber;

Methods#

noSuchMethod() inherited#

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

toString() override#

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Implementation

String toString() => name;

watch()#

Stream<ProcessSignal> watch()

Watch for process signals.

The following ProcessSignals can be listened to:

ProcessSignal.sighup.
ProcessSignal.sigint. Signal sent by e.g. CTRL-C.
ProcessSignal.sigterm. Not available on Windows.
ProcessSignal.sigusr1. Not available on Windows.
ProcessSignal.sigusr2. Not available on Windows.
ProcessSignal.sigwinch. Not available on Windows.

Other signals are disallowed, as they may be used by the VM.

A signal can be watched multiple times, from multiple isolates, where all callbacks are invoked when signaled, in no specific order.

Implementation

Stream<ProcessSignal> watch() => _ProcessUtils._watchSignal(this);

Operators#

operator ==() inherited#

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

Total: It must return a boolean for all arguments. It should never throw.
Reflexive: For all objects o, o == o must be true.
Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.
Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation

external bool operator ==(Object other);

Constants#

sigabrt#

const ProcessSignal sigabrt

Implementation

static const ProcessSignal sigabrt = const ProcessSignal._(6, "SIGABRT");

sigalrm#

const ProcessSignal sigalrm

Implementation

static const ProcessSignal sigalrm = const ProcessSignal._(14, "SIGALRM");

sigbus#

const ProcessSignal sigbus

Implementation

static const ProcessSignal sigbus = const ProcessSignal._(7, "SIGBUS");

sigchld#

const ProcessSignal sigchld

Implementation

static const ProcessSignal sigchld = const ProcessSignal._(17, "SIGCHLD");

sigcont#

const ProcessSignal sigcont

Implementation

static const ProcessSignal sigcont = const ProcessSignal._(18, "SIGCONT");

sigfpe#

const ProcessSignal sigfpe

Implementation

static const ProcessSignal sigfpe = const ProcessSignal._(8, "SIGFPE");

sighup#

const ProcessSignal sighup

Implementation

static const ProcessSignal sighup = const ProcessSignal._(1, "SIGHUP");

sigill#

const ProcessSignal sigill

Implementation

static const ProcessSignal sigill = const ProcessSignal._(4, "SIGILL");

sigint#

const ProcessSignal sigint

Implementation

static const ProcessSignal sigint = const ProcessSignal._(2, "SIGINT");

sigkill#

const ProcessSignal sigkill

Implementation

static const ProcessSignal sigkill = const ProcessSignal._(9, "SIGKILL");

sigpipe#

const ProcessSignal sigpipe

Implementation

static const ProcessSignal sigpipe = const ProcessSignal._(13, "SIGPIPE");

sigpoll#

const ProcessSignal sigpoll

Implementation

static const ProcessSignal sigpoll = const ProcessSignal._(29, "SIGPOLL");

sigprof#

const ProcessSignal sigprof

Implementation

static const ProcessSignal sigprof = const ProcessSignal._(27, "SIGPROF");

sigquit#

const ProcessSignal sigquit

Implementation

static const ProcessSignal sigquit = const ProcessSignal._(3, "SIGQUIT");

sigsegv#

const ProcessSignal sigsegv

Implementation

static const ProcessSignal sigsegv = const ProcessSignal._(11, "SIGSEGV");

sigstop#

const ProcessSignal sigstop

Implementation

static const ProcessSignal sigstop = const ProcessSignal._(19, "SIGSTOP");

sigsys#

const ProcessSignal sigsys

Implementation

static const ProcessSignal sigsys = const ProcessSignal._(31, "SIGSYS");

sigterm#

const ProcessSignal sigterm

Implementation

static const ProcessSignal sigterm = const ProcessSignal._(15, "SIGTERM");

sigtrap#

const ProcessSignal sigtrap

Implementation

static const ProcessSignal sigtrap = const ProcessSignal._(5, "SIGTRAP");

sigtstp#

const ProcessSignal sigtstp

Implementation

static const ProcessSignal sigtstp = const ProcessSignal._(20, "SIGTSTP");

sigttin#

const ProcessSignal sigttin

Implementation

static const ProcessSignal sigttin = const ProcessSignal._(21, "SIGTTIN");

sigttou#

const ProcessSignal sigttou

Implementation

static const ProcessSignal sigttou = const ProcessSignal._(22, "SIGTTOU");

sigurg#

const ProcessSignal sigurg

Implementation

static const ProcessSignal sigurg = const ProcessSignal._(23, "SIGURG");

sigusr1#

const ProcessSignal sigusr1

Implementation

static const ProcessSignal sigusr1 = const ProcessSignal._(10, "SIGUSR1");

sigusr2#

const ProcessSignal sigusr2

Implementation

static const ProcessSignal sigusr2 = const ProcessSignal._(12, "SIGUSR2");

sigvtalrm#

const ProcessSignal sigvtalrm

Implementation

static const ProcessSignal sigvtalrm = const ProcessSignal._(26, "SIGVTALRM");

sigwinch#

const ProcessSignal sigwinch

Implementation

static const ProcessSignal sigwinch = const ProcessSignal._(28, "SIGWINCH");

sigxcpu#

const ProcessSignal sigxcpu

Implementation

static const ProcessSignal sigxcpu = const ProcessSignal._(24, "SIGXCPU");

sigxfsz#

const ProcessSignal sigxfsz

Implementation

static const ProcessSignal sigxfsz = const ProcessSignal._(25, "SIGXFSZ");