No shell prompt message, just a blinking cursor after starting a Python script as a daemon?

Question

• python-daemon-1.5.2-1.el6.noarch

Below is the script that I received from a developer:

import threading
import multiprocessing, os, signal, time, Queue
import time
from suds.client import Client
from hotqueue import HotQueue
from config import config

queue = HotQueue(config['redis_hotqueue_list'], host=config['redis_host'], port=int(config['redis_port']),password=config['redis_pass'], charset="utf-8",db=0)
@queue.worker()
def sendMail(item):    
    key = item[0]        
    domain = item[1]
    fromemail = item[2]
    fromname = item[3]
    subject = item[4]
    content = item[5]
    toemail = item[6]            
    cc = item[7]
    bcc = item[8]
    replyto = item[9]

    # Convert to string variable
    url = config['sendmail_tmdt_url']
    client = Client(url)        
    client.service.send_mail(key,domain, fromemail,subject, content, toemail,fromname, '','','');               
for i in range(10):
    t = threading.Thread(target=sendMail)
    t.setDaemon(True)
    t.start()
while True:
    time.sleep(50)

As you can see, he's using the threading module to make it can be run as a daemon.

I'm going to switch to use the daemon library follow this blog post.

Here's my first try:

from daemon import runner
import logging
import time
import threading
import multiprocessing, os, signal, time, Queue
import time
from suds.client import Client
from hotqueue import HotQueue
from config import config

class Mail():
    def __init__(self):
        self.stdin_path = '/dev/null'
        self.stdout_path = '/dev/tty'
        self.stderr_path = '/dev/tty'
        self.pidfile_path = '/var/run/sendmailworker/sendmailworker.pid'
        self.pidfile_timeout = 1

    def run(self):    
        while True:
            queue = HotQueue(config['redis_hotqueue_list'], host=config['redis_host'], port=int(config['redis_port']), password=config['redis_pass'], charset=r"utf-8", db=0)
            @queue.worker()
            def sendMail(item):
                key = item[0]        
                domain = item[1]
                fromemail = item[2]
                fromname = item[3]
                subject = item[4]
                content = item[5]
                toemail = item[6]            
                cc = item[7]
                bcc = item[8]
                replyto = item[9]

                # Convert to string variable
                url = config['sendmail_tmdt_url']
                client = Client(url)        
                client.service.send_mail(key,domain, fromemail,subject, content, toemail, fromname, '', '', '');            
                logger.debug("result")
            #sleep(50)

mail = Mail()

logger = logging.getLogger("sendmailworker")
logger.setLevel(logging.INFO)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler = logging.FileHandler("/var/log/sendmailworker/sendmailworker.log")
handler.setFormatter(formatter)
logger.addHandler(handler)

daemon_runner = runner.DaemonRunner(mail)
daemon_runner.daemon_context.files_preserve=[handler.stream]
daemon_runner.do_action()

It works but I have to press the Ctrl-C to get the shell prompt after starting:

/etc/init.d/sendmailworker start

Starting server
# started with pid 2586
^C
#

How can I get rid of this problem?

---

Append an ampersand doesn't help:

# /etc/init.d/sendmailworker start &
[1] 4094
# Starting server
started with pid 4099
^C
[1]+  Done                    /etc/init.d/sendmailworker start
#

---

As @Celada pointed out: actually, I already had my shell prompt, but it doesn't display [root@hostname ~]# as usual, just a blinking cursor. Simple pressing Enter make my shell prompt reappear. So the question should be: how to make the started with pid xxxxx come first, at the same line with Starting server, then display my shell prompt?

---

The stop function is working fine:

[root@hostname ~]# /etc/init.d/sendmailworker stop
Stopping server
Terminating on signal 15
[root@hostname ~]# 

How can I do the similar for the start function? Something like this:

[root@hostname ~]# /etc/init.d/sendmailworker start
Starting server
started with pid 30624
[root@hostname ~]# 

Answer 1

You can get your expected beahviour by change

self.stdout_path = '/dev/tty'
self.stderr_path = '/dev/tty'

to:

self.stdout_path = '/dev/null'
self.stderr_path = '/dev/null'

I recommend to write a init script using shell script in your case.

FYI, I can not find any document of runner except its source code.