Grep Regular Expression to Filter Text File

I have a plain text log file on a *nix server that I'd like to be able to view errors as they occur for troubleshooting purposes. The problem is that the log also shows non-errors and errors that I don't care about (error: general).

I did the following:


This worked well in showing me the errors as they occurred but there are a lot of lines with "error" that I don't want to show up.

If I do:


I exclude all the error: general lines but now have all the non-error lines as well. I need to combine the criteria for grep but havent' found a way to do it.

The above works, but it doesn't take advantage of the tail -f command for viewing in real time.

Any gurus who know how to combine these statements?

tail -f logfile.log | grep -v general

i never tryed that, imo does not work, because grep is waiting for
input, and as long tail is running, it gets nothing.

Try:
tail -f error.log | grep error | grep -v general

I did in fact try this, grep twice with pipes connecting them. There is no output whatsoever with this method, for reasons I don't understand. As long as I pipe to grep once, it works (whether I invert the results or not with '-v' doesn't matter).

Incidentally I am running FreeBSD 4.10 and GNU grep 2.4.1 (as far as I can tell). (How do you easily tell the version of apps like grep and awk?)

what /usr/bin/awk

If you do not know the path to awk or whatever file it is try:
what `which awk`

Some systems have the ident command.

This only works if the development team followed cvs standards for file headers.

Thanks for the version-finding info. Every now and then someone wants the version to some utility program and I generally had no answers.

Not sure what shell you have, but this will work with any posix shell like bash or ksh...

I was running tcsh but I quickly installed bash (GNU 2.05b) and gave it a try. Under tcsh it complained about the [['s. Under bash, I am experimenting with it to get the right output. It seems to be working great.

Thanks for the help! The little shell script seems to be just the ticket.