logtail reads a specified file (usually a log file) and writes to the standard output that part of it
which has not been read by previous runs of logtail. It prints the appropriate number of bytes from the
end of logfile, assuming that all changes that are made to it are to add new characters to it.
logfile must be a plain file. A symlink is not allowed.
logtail stores the information about how much of it has already been read in a separate file called
offsetfile. offsetfile can be omitted. If omitted, the file named logfile.offset in the same directory
which contains logfile is used by default.
If offsetfile is not empty, the inode of logfile is checked. If the inode is changed, logtail simply
prints the entire file. If the inode is not changed but logfile is shorter than it was at the last run
of logtail, it writes a warning message to the standard output.