what is the impact of constantly running a tail -f command on a VERY busy file?

Question

I need to monitor a log file for a while and was going to have inittab run tail -f logfile | grep ERROR | xargs -n1 -i mailit.sh {}

Where mailit.sh is just a 2 line program:
echo $1 > error.log
mail -s "Error occured" [e-mail] < error.log

or any other suggestions for realtime monitoring of a log file.
Its VERY BUSY always getting written too.

Thanks,

Answer 1

"tail -f" does a "follow" operation -- it keeps the file open, checks for appending to the file, and never exits -- so I'm not sure this would work.

For what it's worth, we use "tail" on log files that grow by megabytes per minute, without issues. I think that "tail" is fairly easy on system resources (it probably checks to see if the file is longer, with stat() and then gets the bytes).