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import os
import sys
if os.name == 'posix':
def become_daemon(our_home_dir='.', out_log='/dev/null',
err_log='/dev/null', umask=0o022):
"Robustly turn into a UNIX daemon, running in our_home_dir."
# First fork
try:
if os.fork() > 0:
sys.exit(0) # kill off parent
except OSError as e:
sys.stderr.write("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror))
sys.exit(1)
os.setsid()
os.chdir(our_home_dir)
os.umask(umask)
# Second fork
try:
if os.fork() > 0:
os._exit(0)
except OSError as e:
sys.stderr.write("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror))
os._exit(1)
si = open('/dev/null', 'r')
so = open(out_log, 'a+', 0)
se = open(err_log, 'a+', 0)
os.dup2(si.fileno(), sys.stdin.fileno())
os.dup2(so.fileno(), sys.stdout.fileno())
os.dup2(se.fileno(), sys.stderr.fileno())
# Set custom file descriptors so that they get proper buffering.
sys.stdout, sys.stderr = so, se
else:
def become_daemon(our_home_dir='.', out_log=None, err_log=None, umask=0o022):
"""
If we're not running under a POSIX system, just simulate the daemon
mode by doing redirections and directory changing.
"""
os.chdir(our_home_dir)
os.umask(umask)
sys.stdin.close()
sys.stdout.close()
sys.stderr.close()
if err_log:
sys.stderr = open(err_log, 'a', 0)
else:
sys.stderr = NullDevice()
if out_log:
sys.stdout = open(out_log, 'a', 0)
else:
sys.stdout = NullDevice()
class NullDevice:
"A writeable object that writes to nowhere -- like /dev/null."
def write(self, s):
pass
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