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1 import os |
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2 import sys |
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3 |
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4 if os.name == 'posix': |
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5 def become_daemon(our_home_dir='.', out_log='/dev/null', |
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6 err_log='/dev/null', umask=022): |
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7 "Robustly turn into a UNIX daemon, running in our_home_dir." |
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8 # First fork |
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9 try: |
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10 if os.fork() > 0: |
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11 sys.exit(0) # kill off parent |
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12 except OSError, e: |
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13 sys.stderr.write("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror)) |
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14 sys.exit(1) |
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15 os.setsid() |
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16 os.chdir(our_home_dir) |
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17 os.umask(umask) |
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18 |
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19 # Second fork |
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20 try: |
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21 if os.fork() > 0: |
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22 os._exit(0) |
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23 except OSError, e: |
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24 sys.stderr.write("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror)) |
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25 os._exit(1) |
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26 |
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27 si = open('/dev/null', 'r') |
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28 so = open(out_log, 'a+', 0) |
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29 se = open(err_log, 'a+', 0) |
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30 os.dup2(si.fileno(), sys.stdin.fileno()) |
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31 os.dup2(so.fileno(), sys.stdout.fileno()) |
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32 os.dup2(se.fileno(), sys.stderr.fileno()) |
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33 # Set custom file descriptors so that they get proper buffering. |
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34 sys.stdout, sys.stderr = so, se |
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35 else: |
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36 def become_daemon(our_home_dir='.', out_log=None, err_log=None, umask=022): |
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37 """ |
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38 If we're not running under a POSIX system, just simulate the daemon |
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39 mode by doing redirections and directory changing. |
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40 """ |
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41 os.chdir(our_home_dir) |
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42 os.umask(umask) |
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43 sys.stdin.close() |
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44 sys.stdout.close() |
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45 sys.stderr.close() |
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46 if err_log: |
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47 sys.stderr = open(err_log, 'a', 0) |
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48 else: |
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49 sys.stderr = NullDevice() |
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50 if out_log: |
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51 sys.stdout = open(out_log, 'a', 0) |
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52 else: |
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53 sys.stdout = NullDevice() |
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54 |
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55 class NullDevice: |
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56 "A writeable object that writes to nowhere -- like /dev/null." |
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57 def write(self, s): |
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58 pass |