Python os.setsid() Examples

def start_http_server(self, port=80):
        """Starts a simple http server on a choosen port.

        :port: integer defaults to 80
        """
        if(self.__http is None):
            cmd = "python -m SimpleHTTPServer %d" % port
            try:
                self.__http = Popen(cmd, shell=True, preexec_fn=setsid)
                logger.info(
                    'HMI%d - HTTP server started on port %d' % (
                        self.__id, port))

            except OSError, e:
                emsg = repr(e)
                logger.warning(
                    'HMI%d - HTTP server cannot start: %s' % (
                        self.__id, emsg)) 

def fork():
    """fork() -> (pid, master_fd)
    Fork and make the child a session leader with a controlling terminal."""

    try:
        pid, fd = os.forkpty()
    except (AttributeError, OSError):
        pass
    else:
        if pid == CHILD:
            try:
                os.setsid()
            except OSError:
                # os.forkpty() already set us session leader
                pass
        return pid, fd

    master_fd, slave_fd = openpty()
    pid = os.fork()
    if pid == CHILD:
        # Establish a new session.
        os.setsid()
        os.close(master_fd)

        # Slave becomes stdin/stdout/stderr of child.
        os.dup2(slave_fd, STDIN_FILENO)
        os.dup2(slave_fd, STDOUT_FILENO)
        os.dup2(slave_fd, STDERR_FILENO)
        if (slave_fd > STDERR_FILENO):
            os.close (slave_fd)

        # Explicitly open the tty to make it become a controlling tty.
        tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
        os.close(tmp_fd)
    else:
        os.close(slave_fd)

    # Parent and child process.
    return pid, master_fd 

def test_mockPTYSetUid(self):
        """
        Try creating a PTY process with setting its uid: it's almost the same
        path as the standard path, but with a C{switchUID} call before the
        exec.
        """
        cmd = b'/mock/ouch'

        d = defer.Deferred()
        p = TrivialProcessProtocol(d)
        try:
            reactor.spawnProcess(p, cmd, [b'ouch'], env=None,
                                 usePTY=True, uid=8081)
        except SystemError:
            self.assertTrue(self.mockos.exited)
            self.assertEqual(
                self.mockos.actions,
                [('fork', False), 'setsid', ('setuid', 0), ('setgid', 0),
                 ('switchuid', 8081, 1234), 'exec', ('exit', 1)])
        else:
            self.fail("Should not be here") 

def setUp(self):
        super(Base, self).setUp()

        self.lines = []
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.sock.bind(("127.0.0.1", 0))
        self.t = threading.Thread(target=self.readlog)
        self.t.daemon = True
        self.t.start()

        examplepy = os.path.join(os.path.dirname(__file__),
                                 "examples.py")
        if os.name == 'posix':
            kwargs = {
                'preexec_fn': os.setsid
            }
        else:
            kwargs = {
                'creationflags': subprocess.CREATE_NEW_PROCESS_GROUP
            }

        self.subp = subprocess.Popen(['python', examplepy, self.name,
                                      str(self.sock.getsockname()[1])],
                                     **kwargs) 

def start(self):
        self.cmdline = (self.backend,
                     '-nostats',
                     '-loglevel', 'error', # suppress warnings
                     '-y',
                     '-r', '%d' % self.frames_per_sec,

                     # input
                     '-f', 'rawvideo',
                     '-s:v', '{}x{}'.format(*self.wh),
                     '-pix_fmt',('rgb32' if self.includes_alpha else 'rgb24'),
                     '-i', '-', # this used to be /dev/stdin, which is not Windows-friendly

                     # output
                     '-vcodec', 'libx264',
                     '-pix_fmt', 'yuv420p',
                     self.output_path
                     )

        logger.debug('Starting ffmpeg with "%s"', ' '.join(self.cmdline))
        if hasattr(os,'setsid'): #setsid not present on Windows
            self.proc = subprocess.Popen(self.cmdline, stdin=subprocess.PIPE, preexec_fn=os.setsid)
        else:
            self.proc = subprocess.Popen(self.cmdline, stdin=subprocess.PIPE) 

def daemonize(logfile = None):
    # Fork once
    if os.fork() != 0:
        os._exit(0)
    # Create new session
    os.setsid()
    if os.fork() != 0:
        os._exit(0)
    os.chdir('/')
    fd = os.open('/dev/null', os.O_RDWR)
    os.dup2(fd, sys.__stdin__.fileno())
    if logfile != None:
        fake_stdout = open(logfile, 'a', 1)
        sys.stdout = fake_stdout
        sys.stderr = fake_stdout
        fd = fake_stdout.fileno()
    os.dup2(fd, sys.__stdout__.fileno())
    os.dup2(fd, sys.__stderr__.fileno())
    if logfile == None:
        os.close(fd) 

def launch_proc_with_pty(args, stdin=None, stdout=None, stderr=None, echo=True):
    """Similar to pty.fork, but handle stdin/stdout according to parameters
    instead of connecting to the pty

    :return tuple (subprocess.Popen, pty_master)
    """

    def set_ctty(ctty_fd, master_fd):
        os.setsid()
        os.close(master_fd)
        fcntl.ioctl(ctty_fd, termios.TIOCSCTTY, 0)
        if not echo:
            termios_p = termios.tcgetattr(ctty_fd)
            # termios_p.c_lflags
            termios_p[3] &= ~termios.ECHO
            termios.tcsetattr(ctty_fd, termios.TCSANOW, termios_p)
    (pty_master, pty_slave) = os.openpty()
    # pylint: disable=not-an-iterable
    p = yield from asyncio.create_subprocess_exec(*args,
        stdin=stdin,
        stdout=stdout,
        stderr=stderr,
        preexec_fn=lambda: set_ctty(pty_slave, pty_master))
    os.close(pty_slave)
    return p, open(pty_master, 'wb+', buffering=0) 

def start(self):
        self.cmdline = (self.backend,
                     '-nostats',
                     '-loglevel', 'error', # suppress warnings
                     '-y',
                     '-r', '%d' % self.frames_per_sec,

                     # input
                     '-f', 'rawvideo',
                     '-s:v', '{}x{}'.format(*self.wh),
                     '-pix_fmt',('rgb32' if self.includes_alpha else 'rgb24'),
                     '-i', '-', # this used to be /dev/stdin, which is not Windows-friendly

                     # output
                     '-vcodec', 'libx264',
                     '-pix_fmt', 'yuv420p',
                     self.output_path
                     )

        logger.debug('Starting ffmpeg with "%s"', ' '.join(self.cmdline))
        if hasattr(os,'setsid'): #setsid not present on Windows
            self.proc = subprocess.Popen(self.cmdline, stdin=subprocess.PIPE, preexec_fn=os.setsid)
        else:
            self.proc = subprocess.Popen(self.cmdline, stdin=subprocess.PIPE) 

def daemonize(logfile = None):
    # Fork once
    if os.fork() != 0:
        os._exit(0)
    # Create new session
    os.setsid()
    if os.fork() != 0:
        os._exit(0)
    os.chdir('/')
    fd = os.open('/dev/null', os.O_RDWR)
    os.dup2(fd, sys.__stdin__.fileno())
    if logfile != None:
        fake_stdout = open(logfile, 'a', 1)
        sys.stdout = fake_stdout
        sys.stderr = fake_stdout
        fd = fake_stdout.fileno()
    os.dup2(fd, sys.__stdout__.fileno())
    os.dup2(fd, sys.__stderr__.fileno())
    if logfile == None:
        os.close(fd) 

def start(self):
        self.command = "%s %s -%c -R %s -s %d" % \
                (
                    INJECTOR,
                    " ".join(self.settings.args),
                    self.settings.synth_mode,
                    "-0" if self.settings.root else "",
                    self.settings.seed
                )
        self.process = subprocess.Popen(
            "exec %s" % self.command,
            shell=True,
            stdout=subprocess.PIPE,
            stdin=subprocess.PIPE,
            preexec_fn=os.setsid
            ) 

def background(self):
        # first fork
        # root process waits for the child in order not to have zombies in the system
        pid = os.fork()
        if pid > 0:
            # parent - root process wait for first child and exits
            os.wait()
            sys.exit(0)

        # first child
        # setup own environment
        os.chdir(self.root)
        os.umask(0)
        os.setsid()

        # second fork
        # first-fork child produces the real worker process and exits
        # first-fork child is being waited now by root process
        pid = os.fork()
        if pid > 0:
            sys.exit(0)

        # worker
        signal.signal(signal.SIGINT, self.shutdown)
        signal.signal(signal.SIGTERM, self.shutdown)

        # handle pid file
        atexit.register(self.delete_pidfile)
        self.write_pidfile()

        # handle streams
        self.redirect_std_streams() 

def getProcess(self):
        if self.proc:
            return self.proc
        console_path = os.path.join(os.path.dirname(sys.argv[0]), 'console.py ')
        write_fd = self.loop.watch_pipe(self.onUpdate)
        self.proc = subprocess.Popen(
            [sys.executable + ' ' + console_path + ' ' + self.connectionname + ' json'],
            stdout=write_fd,
            preexec_fn=os.setsid,
            close_fds=True,
            shell=True)
        return self.proc 

def _preexec_val(self):
        return os.setsid if sublime.platform() != "windows" else None 

def pty_make_controlling_tty(tty_fd):
    '''This makes the pseudo-terminal the controlling tty. This should be
    more portable than the pty.fork() function. Specifically, this should
    work on Solaris. '''

    child_name = os.ttyname(tty_fd)

    # Disconnect from controlling tty, if any.  Raises OSError of ENXIO
    # if there was no controlling tty to begin with, such as when
    # executed by a cron(1) job.
    try:
        fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
        os.close(fd)
    except OSError as err:
        if err.errno != errno.ENXIO:
            raise

    os.setsid()

    # Verify we are disconnected from controlling tty by attempting to open
    # it again.  We expect that OSError of ENXIO should always be raised.
    try:
        fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
        os.close(fd)
        raise PtyProcessError("OSError of errno.ENXIO should be raised.")
    except OSError as err:
        if err.errno != errno.ENXIO:
            raise

    # Verify we can open child pty.
    fd = os.open(child_name, os.O_RDWR)
    os.close(fd)

    # Verify we now have a controlling tty.
    fd = os.open("/dev/tty", os.O_WRONLY)
    os.close(fd) 

def session_start(self):
        self._log("SESSION_START")
        self.process = subprocess.Popen(SHELL, shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, preexec_fn=os.setsid)

        flags = fcntl.fcntl(self.process.stdout, fcntl.F_GETFL)
        fcntl.fcntl(self.process.stdout, fcntl.F_SETFL, flags | os.O_NONBLOCK) 

def cmd_exe(cmd, timeout=-1):
    """
    Executes a command through the shell.
    timeout in minutes! so 1440 mean is 24 hours.
    -1 means never
    returns (ret_code, stdout, stderr, datetime)
    where ret_code is the exit code for the command executed
    stdout/err is the Standard Output Error from the command
    and datetime is a datetime object of the execution time
    """
    t_start = time.time()
    proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE, close_fds=True,
                            preexec_fn=os.setsid)
    signal.signal(signal.SIGALRM, alarm_handler)
    if timeout > 0:
        signal.alarm(int(timeout * 60))
    try:
        stdoutVal, stderrVal = proc.communicate()
        signal.alarm(0)  # reset the alarm
    except Alarm:
        logging.error(("Command was taking too long. "
                       "Automatic Timeout Initiated after %d"), timeout)
        os.killpg(proc.pid, signal.SIGTERM)
        proc.kill()
        return 214, None, None, datetime.timedelta(seconds=int(time.time() - t_start))
    t_end = time.time()

    stdoutVal = bytes.decode(stdoutVal)
    retCode = proc.returncode
    return retCode, stdoutVal, stderrVal, datetime.timedelta(seconds=int(t_end - t_start)) 

def poke(self, context):
        """
        Execute the bash command in a temporary directory
        which will be cleaned afterwards
        """
        bash_command = self.bash_command
        self.log.info("Tmp dir root location: \n %s", gettempdir())
        with TemporaryDirectory(prefix='airflowtmp') as tmp_dir:
            with NamedTemporaryFile(dir=tmp_dir, prefix=self.task_id) as f:
                f.write(bytes(bash_command, 'utf_8'))
                f.flush()
                fname = f.name
                script_location = tmp_dir + "/" + fname
                self.log.info("Temporary script location: %s", script_location)
                self.log.info("Running command: %s", bash_command)
                resp = Popen(  # pylint: disable=subprocess-popen-preexec-fn
                    ['bash', fname],
                    stdout=PIPE, stderr=STDOUT,
                    close_fds=True, cwd=tmp_dir,
                    env=self.env, preexec_fn=os.setsid)

                self.log.info("Output:")
                for line in iter(resp.stdout.readline, b''):
                    line = line.decode(self.output_encoding).strip()
                    self.log.info(line)
                resp.wait()
                self.log.info("Command exited with return code %s", resp.returncode)

                return not resp.returncode 

def run_command(self, run_with=None):
        """
        Run the task command.

        :param run_with: list of tokens to run the task command with e.g. ``['bash', '-c']``
        :type run_with: list
        :return: the process that was run
        :rtype: subprocess.Popen
        """
        run_with = run_with or []
        full_cmd = run_with + self._command

        self.log.info("Running on host: %s", get_hostname())
        self.log.info('Running: %s', full_cmd)
        # pylint: disable=subprocess-popen-preexec-fn
        proc = subprocess.Popen(
            full_cmd,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            universal_newlines=True,
            close_fds=True,
            env=os.environ.copy(),
            preexec_fn=os.setsid
        )

        # Start daemon thread to read subprocess logging output
        log_reader = threading.Thread(
            target=self._read_task_logs,
            args=(proc.stdout,),
        )
        log_reader.daemon = True
        log_reader.start()
        return proc 

def setsid(self):
        """
        Fake C{os.setsid}. Save action.
        """
        self.actions.append('setsid') 

def start(self):
        print('(ibash) Bash process started...')
        self.child  = Popen(self.cmd, shell=0, stdout=PIPE, stdin=PIPE, 
                            preexec_fn=setsid, stderr=STDOUT,  env=environ)
        

        self.stdout = Device(self.child.stdout)
        self.stdin  = Device(self.child.stdin)

        Stdout(self.stdout)
        Stdin(self.stdin)

        xmap(self.stdout, LOAD, lambda con, data: sys.stdout.write(data.decode('utf8')))
        xmap(self.stdin, CLOSE, lambda dev, err: lose(dev))
        xmap(self.stdout, CLOSE, lambda dev, err: lose(dev)) 

def start(self):
        if self.is_active:
            print(f"[Cluster {self.id}] Already active.")
            return
        self.started_at = time.time()
        self._process = await asyncio.create_subprocess_shell(
            self.command,
            stdin=asyncio.subprocess.DEVNULL,
            stdout=asyncio.subprocess.PIPE,
            stderr=asyncio.subprocess.PIPE,
            preexec_fn=os.setsid,
            limit=1024 * 256,
        )
        self.status = "running"
        self.started_at = time.time()
        print(f"[Cluster {self.id}] The cluster is starting.")
        await asyncio.wait([self.read_stream(self._process.stdout), self.read_stream(self._process.stderr)])
        return self 

def fork():
    """fork() -> (pid, master_fd)
    Fork and make the child a session leader with a controlling terminal."""

    try:
        pid, fd = os.forkpty()
    except (AttributeError, OSError):
        pass
    else:
        if pid == CHILD:
            try:
                os.setsid()
            except OSError:
                # os.forkpty() already set us session leader
                pass
        return pid, fd

    master_fd, slave_fd = openpty()
    pid = os.fork()
    if pid == CHILD:
        # Establish a new session.
        os.setsid()
        os.close(master_fd)

        # Slave becomes stdin/stdout/stderr of child.
        os.dup2(slave_fd, STDIN_FILENO)
        os.dup2(slave_fd, STDOUT_FILENO)
        os.dup2(slave_fd, STDERR_FILENO)
        if (slave_fd > STDERR_FILENO):
            os.close (slave_fd)

        # Explicitly open the tty to make it become a controlling tty.
        tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
        os.close(tmp_fd)
    else:
        os.close(slave_fd)

    # Parent and child process.
    return pid, master_fd 

def test_mockForkTTY(self):
        """
        Test a TTY spawnProcess: check the path of the client code:
        fork, exec, exit.
        """
        cmd = b'/mock/ouch'

        d = defer.Deferred()
        p = TrivialProcessProtocol(d)
        self.assertRaises(SystemError, reactor.spawnProcess, p, cmd, [b'ouch'],
                          env=None, usePTY=True)
        self.assertTrue(self.mockos.exited)
        self.assertEqual(
            self.mockos.actions,
            [("fork", False), "setsid", "exec", ("exit", 1)]) 

def fork():
    """fork() -> (pid, master_fd)
    Fork and make the child a session leader with a controlling terminal."""

    try:
        pid, fd = os.forkpty()
    except (AttributeError, OSError):
        pass
    else:
        if pid == CHILD:
            try:
                os.setsid()
            except OSError:
                # os.forkpty() already set us session leader
                pass
        return pid, fd

    master_fd, slave_fd = openpty()
    pid = os.fork()
    if pid == CHILD:
        # Establish a new session.
        os.setsid()
        os.close(master_fd)

        # Slave becomes stdin/stdout/stderr of child.
        os.dup2(slave_fd, STDIN_FILENO)
        os.dup2(slave_fd, STDOUT_FILENO)
        os.dup2(slave_fd, STDERR_FILENO)
        if (slave_fd > STDERR_FILENO):
            os.close (slave_fd)

        # Explicitly open the tty to make it become a controlling tty.
        tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
        os.close(tmp_fd)
    else:
        os.close(slave_fd)

    # Parent and child process.
    return pid, master_fd 

def daemonize():
    # See http://www.erlenstar.demon.co.uk/unix/faq_toc.html#TOC16
    if os.fork():   # launch child and...
        os._exit(0) # kill off parent
    os.setsid()
    if os.fork():   # launch child and...
        os._exit(0) # kill off parent again.
    null = os.open('/dev/null', os.O_RDWR)
    for i in range(3):
        try:
            os.dup2(null, i)
        except OSError as e:
            if e.errno != errno.EBADF:
                raise
    os.close(null) 

def fork():
    """fork() -> (pid, master_fd)
    Fork and make the child a session leader with a controlling terminal."""

    try:
        pid, fd = os.forkpty()
    except (AttributeError, OSError):
        pass
    else:
        if pid == CHILD:
            try:
                os.setsid()
            except OSError:
                # os.forkpty() already set us session leader
                pass
        return pid, fd

    master_fd, slave_fd = openpty()
    pid = os.fork()
    if pid == CHILD:
        # Establish a new session.
        os.setsid()
        os.close(master_fd)

        # Slave becomes stdin/stdout/stderr of child.
        os.dup2(slave_fd, STDIN_FILENO)
        os.dup2(slave_fd, STDOUT_FILENO)
        os.dup2(slave_fd, STDERR_FILENO)
        if (slave_fd > STDERR_FILENO):
            os.close (slave_fd)

        # Explicitly open the tty to make it become a controlling tty.
        tmp_fd = os.open(os.ttyname(STDOUT_FILENO), os.O_RDWR)
        os.close(tmp_fd)
    else:
        os.close(slave_fd)

    # Parent and child process.
    return pid, master_fd 

def _boot(self):
        # Child processes don't start without a HOME dir
        if not self.env.get("HOME", False):
            raise HerokuStartupError('"HOME" environment not set... aborting.')

        port = self.config.get("base_port")
        web_dynos = self.config.get("num_dynos_web")
        worker_dynos = self.config.get("num_dynos_worker")
        commands = [
            self.shell_command,
            "local",
            "-p",
            str(port),
            "web={},worker={}".format(web_dynos, worker_dynos),
        ]
        try:
            options = {
                "stdout": subprocess.PIPE,
                "stderr": subprocess.STDOUT,
                "env": self.env,
                "preexec_fn": os.setsid,
            }
            if six.PY3:
                options["encoding"] = "utf-8"
            self._process = subprocess.Popen(commands, **options)
        except OSError:
            self.out.error("Couldn't start Heroku for local debugging.")
            raise 

def detach_process_context():
    """Datach process context.

    Does it in three steps:

    1. Forks and exists parent process.
    This detaches us from shell, and since the child will have a new
    PID but will inherit the Group PID from parent, the new process
    will not be a group leader.

    2. Call 'setsid' to create a new session.
    This makes the process a session leader of a new session, process
    becomes the process group leader of a new process group and it
    doesn't have a controlling terminal.

    3. Form and exit parent again.
    This guarantees that the daemon is not a session leader, which
    prevents it from acquiring a controlling terminal.

    Reference: “Advanced Programming in the Unix Environment”,
    section 13.3, by W. Richard Stevens.
    """
    def fork_and_exit_parent(error_message):
        try:
            if os.fork() > 0:
                # Don't need to call 'sys.exit', as we don't want to
                # run any python interpreter clean-up handlers
                os._exit(0)
        except OSError as ex:
            raise DaemonError(
                '{}: [{}] {}'.format(error_message, ex.errno,
                                     ex.strerror)) from ex

    fork_and_exit_parent(error_message='Failed the first fork')
    os.setsid()
    fork_and_exit_parent(error_message='Failed the second fork') 

def _launch_command(self, run_cmd):
        """runs command that runs the start script in a container or on bare metal and exits on ctrl c"""
        p = subprocess.Popen(run_cmd, preexec_fn=os.setsid)
        try:
            p.communicate()
        except KeyboardInterrupt:
            os.killpg(os.getpgid(p.pid), signal.SIGKILL) 

def setUp(self):
        super(IntegTestBase, self).setUp()
        prefix = "TabPy_IntegTest_"
        self.tmp_dir = tempfile.mkdtemp(prefix=prefix)

        # create temporary state.ini
        orig_state_file_name = os.path.abspath(
            self._get_state_file_path() + "/state.ini"
        )
        self.state_file_name = os.path.abspath(self.tmp_dir + "/state.ini")
        if orig_state_file_name != self.state_file_name:
            shutil.copyfile(orig_state_file_name, self.state_file_name)

        # create config file
        orig_config_file_name = os.path.abspath(self._get_config_file_name())
        self.config_file_name = os.path.abspath(
            self.tmp_dir + "/" + os.path.basename(orig_config_file_name)
        )
        if orig_config_file_name != self.config_file_name:
            shutil.copyfile(orig_config_file_name, self.config_file_name)

        # Platform specific - for integration tests we want to engage
        # startup script
        with open(self.tmp_dir + "/output.txt", "w") as outfile:
            cmd = ["tabpy", "--config=" + self.config_file_name]
            preexec_fn = None
            if platform.system() == "Windows":
                self.py = "python"
            else:
                self.py = "python3"
                preexec_fn = os.setsid

            coverage.process_startup()
            self.process = subprocess.Popen(
                cmd, preexec_fn=preexec_fn, stdout=outfile, stderr=outfile
            )

            # give the app some time to start up...
            time.sleep(5)