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  1. #!/usr/bin/python
  2. import time
  3. from optparse import OptionParser
  4.  
  5. SLEEP_INTERVAL = 1.0
  6. i=0
  7. def readlines_then_tail(fin):
  8.     print "Iterate through lines and then tail for further lines."
  9.     i=0
  10.     while True:
  11.         line = fin.readline()
  12.         if line:
  13. 	    i=i+1
  14.             print "line = ",i,line
  15.             yield line
  16.         else:
  17.             tail(fin)
  18.  
  19. def tail(fin):
  20.     print "Listen for new lines added to file."
  21.     while True:
  22.         where = fin.tell()
  23. 	print "where = ",where
  24.         line = fin.readline()
  25.         if not line:
  26. 	    print "Going to sleep"
  27. 	    print "zzz.zzz.zzz.zzz"
  28.             time.sleep(SLEEP_INTERVAL)
  29. 	    print "Jusi woke up !"
  30.             fin.seek(where)
  31.         else:
  32.             yield line
  33.  
  34. def main():
  35.     p = OptionParser("usage: tail.py file")
  36.     (options, args) = p.parse_args()
  37.     if len(args) < 1:
  38.         p.error("must specify a file to watch")
  39.     with open(args[0], 'r') as fin:
  40.         for line in readlines_then_tail(fin):
  41.             print line.strip()
  42.  
  43. if __name__ == '__main__':
  44.     main()
  45.  
Runtime error #stdin #stdout #stderr 0.01s 24888KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
Usage: tail.py file

prog: error: must specify a file to watch
https://ideone.com/F5miNm
language:
Python (cpython 2.7.16)
created:
6 years ago
visibility:
public

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