├── setup.py
├── example1.py
├── README.md
└── tail.py


/setup.py:
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 1 | # !/usr/bin/env python
 2 | 
 3 | from distutils.core import setup
 4 | 
 5 | setup(name='python-tail',
 6 |     description='Unix Tail follow implementation',
 7 |     author='Kasun Herath',
 8 |     author_email='kasunh01@gmail.com',
 9 |     py_modules=['tail'],
10 |     )
11 | 
12 | 
13 | 


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/example1.py:
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 1 | #!/usr/bin/env python
 2 | 
 3 | ''' 
 4 | python-tail example.
 5 | Does a tail follow against /var/log/syslog with a time interval of 5 seconds.
 6 | Prints recieved new lines to standard out '''
 7 | 
 8 | import tail
 9 | 
10 | def print_line(txt):
11 |     ''' Prints received text '''
12 |     print(txt)
13 | 
14 | t = tail.Tail('/var/log/syslog')
15 | t.register_callback(print_line)
16 | t.follow(s=5)
17 | 
18 | 
19 | 


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/README.md:
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 1 | # python-tail - Unix tail follow implementation in Python #
 2 | 
 3 | ## Installation ##
 4 | 
 5 | python setup.py install
 6 | 
 7 | ## Basic Usage ##
 8 |     import tail
 9 |     
10 |     # Create a tail instance
11 |     t = tail.Tail('file-to-be-followed')
12 | 
13 |     # Register a callback function to be called when a new line is found in the followed file. 
14 |     # If no callback function is registerd, new lines would be printed to standard out.
15 |     t.register_callback(callback_function)
16 | 
17 |     # Follow the file with 5 seconds as sleep time between iterations. 
18 |     # If sleep time is not provided 1 second is used as the default time.
19 |     t.follow(s=5)
20 |      
21 | 


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/tail.py:
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 1 | #!/usr/bin/env python
 2 | 
 3 | '''
 4 | Python-Tail - Unix tail follow implementation in Python. 
 5 | 
 6 | python-tail can be used to monitor changes to a file.
 7 | 
 8 | Example:
 9 |     import tail
10 | 
11 |     # Create a tail instance
12 |     t = tail.Tail('file-to-be-followed')
13 | 
14 |     # Register a callback function to be called when a new line is found in the followed file. 
15 |     # If no callback function is registered, new lines would be printed to standard out.
16 |     t.register_callback(callback_function)
17 | 
18 |     # Follow the file with 5 seconds as sleep time between iterations. 
19 |     # If sleep time is not provided 1 second is used as the default time.
20 |     t.follow(s=5) '''
21 | 
22 | # Author - Kasun Herath <kasunh01 at gmail.com>
23 | # Source - https://github.com/kasun/python-tail
24 | 
25 | import os
26 | import sys
27 | import time
28 | 
29 | class Tail(object):
30 |     ''' Represents a tail command. '''
31 |     def __init__(self, tailed_file):
32 |         ''' Initiate a Tail instance.
33 |             Check for file validity, assigns callback function to standard out.
34 |             
35 |             Arguments:
36 |                 tailed_file - File to be followed. '''
37 | 
38 |         self.check_file_validity(tailed_file)
39 |         self.tailed_file = tailed_file
40 |         self.callback = sys.stdout.write
41 | 
42 |     def follow(self, s=1):
43 |         ''' Do a tail follow. If a callback function is registered it is called with every new line. 
44 |         Else printed to standard out.
45 |     
46 |         Arguments:
47 |             s - Number of seconds to wait between each iteration; Defaults to 1. '''
48 | 
49 |         with open(self.tailed_file) as file_:
50 |             # Go to the end of file
51 |             file_.seek(0,2)
52 |             while True:
53 |                 curr_position = file_.tell()
54 |                 line = file_.readline()
55 |                 if not line:
56 |                     file_.seek(curr_position)
57 |                     time.sleep(s)
58 |                 else:
59 |                     self.callback(line)
60 | 
61 |     def register_callback(self, func):
62 |         ''' Overrides default callback function to provided function. '''
63 |         self.callback = func
64 | 
65 |     def check_file_validity(self, file_):
66 |         ''' Check whether the a given file exists, readable and is a file '''
67 |         if not os.access(file_, os.F_OK):
68 |             raise TailError("File '%s' does not exist" % (file_))
69 |         if not os.access(file_, os.R_OK):
70 |             raise TailError("File '%s' not readable" % (file_))
71 |         if os.path.isdir(file_):
72 |             raise TailError("File '%s' is a directory" % (file_))
73 | 
74 | class TailError(Exception):
75 |     def __init__(self, msg):
76 |         self.message = msg
77 |     def __str__(self):
78 |         return self.message
79 | 


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