new content notification from a log file

[Oliver]

dear all,

I have the following situation that I don't have a good solution:

One process periodically will append its output to a file (which is
not under my control), I want to write a ruby problem to detect and
report only the *new* stuff that went into the output file ... Besides
the brute force way such as opening the file and counting the lines
etc, is there a better solution to it?

Thanks for help

Oliver

 

[Gary Wright]

One process periodically will append its output to a file (which is
not under my control), I want to write a ruby problem to detect and
report only the *new* stuff that went into the output file ... Besides
the brute force way such as opening the file and counting the lines
etc, is there a better solution to it?

You can use File.stat('filename').size to get the number of bytes in
the file or .mtime to find the last modification time. If the bytes
and/or time changes you can then open the file and grab the new lines.

Gary Wright

 

[Oliver]

Thanks to both of you for the solution.

The double while loop seems a bit more concise, but it depends on
File#gets method handles the changing file content correctly. I will
give it a spin.

Best,

Oliver