This code analyse Elastic Load Balancing Access log files. Other flavortail -F file.txt 2>/dev/null | python lines.pylines.pyimport syswhile 1: try: line = sys.stdin.readline() if not line: break print line.strip() except Exception, e: raise e This code tails a log file - trying follow a log file at real time. Source: http://ftp.tummy.com/pub/tummy/Python/tail.py#!/usr/bin/env python'''A module which implements a unix-like "tail" of a file.A callback is made for every new line found in the file. Optionsspecify whether the existing contents of the file should be reador ignored.@author Sean Reifschneider < jafo@tummy.com >@version $Revision: 1.52 $Released under the GPLv2 or any later version.If a file is emptied or removed, the tail will continue reading lineswhich are written in the new place.Simple example: import tail def callback(line): print 'Line: "%s"' % string.rstrip(line) tail.tail('/var/log/all', callback).mainloop()'''import timeimport stringimport osclass tail: def __init__(self, filename, callback, tailbytes = 0): '''Create a new tail instance. Create a tail object which periodicly polls the specified file looking for new data which was written. The callback routine is called for each new line found in the file. @return Nothing @param filename File to read. @param callback Function which takes one argument, called with each line read from the file. @param tailbytes Specifies bytes from end of file to start reading (defaults to 0, meaning skip entire file, -1 means read full file). ''' self.skip = tailbytes self.filename = filename self.callback = callback self.fp = None self.lastSize = 0 self.lastInode = -1 self.data = '' def process(self): '''Examine file looking for new lines. When called, this function will process all lines in the file being tailed, detect the original file being renamed or reopened, etc... This should be called periodicly to look for activity on the file. @return Nothing ''' # open file if it's not already open if not self.fp: try: self.fp = open(self.filename, 'r') stat = os.stat(self.filename) self.lastIno = stat[1] if self.skip >= 0 and stat[6] > self.skip: self.fp.seek(0 - (self.skip), 2) self.skip = -1 self.lastSize = 0 except: if self.fp: self.fp.close() self.skip = -1 # if the file doesn't exist, we don't skip self.fp = None if not self.fp: return # check to see if file has moved under us try: stat = os.stat(self.filename) thisSize = stat[6] thisIno = stat[1] if thisSize < self.lastSize or thisIno != self.lastIno: raise Exception except: self.fp.close() self.fp = None self.data = '' return # read if size has changed if self.lastSize < thisSize: while 1: thisData = self.fp.read(4096) if len(thisData) < 1: break self.data = self.data + thisData # process lines within the data while 1: pos = string.find(self.data, '\n') if pos < 0: break line = self.data[:pos] self.data = self.data[pos + 1:] # line is line read from file if self.callback: self.callback(line) self.lastSize = thisSize self.lastIno = thisIno def mainloop(self, sleepfor = 5): '''Loop forever processing activity on the tail object. This routine is intended to be called in programs which do not need to do other processing. This routine never returns. @return Never returns @param sleepfor Seconds between processing (default is 5 seconds). ''' while 1: self.process() time.sleep(sleepfor)if __name__ == "__main__": def callback(line): print