Re: tail -f will not work with IIS generated log files

[mitchell balsam]

Yep,

I think your correct. Its not bash/tail its IIS.

I do a ls-la on the file, do some web access, ls -la it again. Same size.

Thanks

Mitch

> Hi,
>
> if I "tail -f" a log file generated by the IIS web server, tail does not
> show changes to the file.
>
> When I control-c and rerun the command I see the changes.
>
> Not sure if this is a prolem with bash/tail or IIS.
>
> Any ideas?
>

The problem is the way IIS generates log files.  If you watch the file size
of the log file during the course of the day, you'll notice it allocates a
large portion of the file at once (on my dinky internal site, it allocates
65K a day in the morning), and fills that up, or erases the unused portion
at the end of the day.  I haven't looked at tail's source, but my guess it
waits for the file to grow instead of finding the end of the "used" space of
the log file.

If I further had to guess, this is to prevent parts of the log not being
attached to the FAT table as part of the log file when the system crashes,
and being lost during chkdsk in the reboot. (Or partially saved as "Lost
clusters" and given a random name)

Robert Cicconetti