#!/usr/bin/python2.7 # vim:ai:et:ts=4:sw=4:wm=0:encoding=utf8:fileencoding=utf8 """ tail.py ======= Exports 'follow', which yields linewise the content being added to a text file, similar to unix' "tail -f" functionality. As a demonstration, you can run this script directly with an argument, the filename you wish to follow. I use it to follow my httpd logs: $ python2.7 tail.py /var/log/httpd/access_log .... """ __all__ = ('follow',) import time def follow(stream): "Follow the live contents of a text file." line = '' for block in iter(lambda:stream.read(1024), None): if '\n' in block: # Only enter this block if we have at least one line to yield. # The +[''] part is to catch the corner case of when a block # ends in a newline, in which case it would repeat a line. for line in (line+block).splitlines(True)+['']: if line.endswith('\n'): yield line # When exiting the for loop, 'line' has any remaninig text. elif not block: # Wait for data. time.sleep(1.0) # The End. if __name__ == '__main__': # As a simple demonstration, run it with the filename to tail. import sys with open(sys.argv, 'rt') as following: following.seek(-64, 2) try: for line in follow(following): sys.stdout.write(line) except KeyboardInterrupt: pass # Fin.