manu's blog

or, finding last few lines in a file. Ok. So, last solution was not perfect. It just returned last line from a file. What about returning say 10 or may be more lines? Here is the modified Tail function to do that: def Tail(filepath, nol=10, read_size=1024): """ This function returns the last line of a file. Args: filepath: path to file nol: number of lines to print read_size: data is read in chunks of this size (optional, default=1024) Raises: IOError if file cannot be processed. """ f = open(filepath, 'rU') # U is to open it with Universal newline support offset = read_size f.seek(0, 2) file_size = f.tell() while 1: if file_size offset = file_size f.seek(-1*offset, 2) read_str = f.read(offset) # Remove newline at the end if read_str[offset - 1] == '\n': read_str = read_str[:-1] lines = read_str.split('\n') if len(lines) >= nol: # Got nol lines ...

or, finding last line of a huge file.. How do you find the last line of a 2 GB log file from within your program? You don't want to go through the whole file, right? Right. What you want to do is, you want to start reading from end until you find a newline character. Here is how I did it in Python: def Tail(filepath, read_size=1024): """ This function returns the last line of a file. Args: filepath: path to file read_size: data is read in chunks of this size (optional, default=1024) Raises: IOError if file cannot be processed. """ f = open(filepath, 'rU') # U is to open it with Universal newline support offset = read_size f.seek(0, 2) file_size = f.tell() while 1: if file_size offset = file_size f.seek(-1*offset, 2) read_str = f.read(offset) # Remove newline at the end if read_str[offset - 1] == '\n': read_str = read_str[0:-1] lines = read_str.split('\n') ...