Edit an opened file

[swhunter]

We're running a server program that keep adding message into a log file, and it's supposed to run 24/7. Is there any way that we can edit this log file or clean it up while it's still available for the server program. We are using script below in our cron script; however, the server loses the file pointer and won't be able to log the message right after this script is called. Is there any command to accomplish this in Unix?
Thank you.

mv $1 $1.$$
grep -v $2 $1.$$ >> $1
rm $1.$$

 

[Annihilannic]

Try changing the first mv to a cp, that way the original inode is retained and it may continue to write to the file after its been cleaned up.

You'll also need to change >> to > if you use this method.

Unfortunately some programmes remember the exact offset they were writing to in the file, so if you reduce the log file from 4MB to 1MB, say, they still write at the 4MB offset and the file size just jumps up to 4MB again as soon as more data is written to the log. Annihilannic.