Tim's questions

I'm looking to set up monitoring and alerting for java server based app and want to find some best practices for monitoring JVM specific metrics and for designing alerts based on those metrics.

So what are the key JVM metrics to monitor? Some possible contenders:

• Heap space used
• CPU usage
• GC frequency
• Time spent in GC
• Thread count
• Class count
• Object count

And once you start watching some metrics, what are good alerting strategies for said metrics? CPU usage seems like an easy one, but something like heap space seems good to monitor and be able to view, but it doesn't translate so well into an alertable metric as you expect it will grow to capacity, triggering GC. But something like time spent in GC, especially as a ratio to overall time seems like it has good alerting potential.

I'm not looking for a tool per se (ie. Hyperic or Nagios) to perform the monitoring, but if there is one that has an especially good Java template/default graph/rule set, that would be a handy pointer.

I want to parse some arguments to a bash script using getopts but want to be able to access the remaining args that are not included in the option list. So for example, if I have a call:

% script -a -b param -c param -d other arguments here

I would have:

while getopts "ab:c:d" opt ; do
.
done

What is the easiest way to get "other arguments here", which should be unprocessed by getopts?

I have a fairly large dataset which I need to import into MySQL. I'd like to do so as efficiently as possible as I am going to need to do this repeatedly. Are there tricks for this? Is there some way which is more efficient than extended INSERT statements?

To address the questions in the comment, the original format is in XML, though I already have a transformer to put it into CSV format. I'm working with MySQL 5.1.x and the target database is InnoDB. There are relationships between the data, but I do not have any constraints and the data isn't clean enough in most cases to impose them.

I have been a zsh user for quite some time (before that tcsh and before that csh). I am quite happy with it, but was wondering if there are any compelling features of bash that do not exist in zsh. And conversely, are there zsh features which do not exist in bash. My current feel is that bash is better:

• If you are familiar with it already and don't want to learn new syntax.
• It is going to exist on most all *nix machines by default, whereas zsh may be an extra install.

Not trying to start a religious battle here, which is why I'm just looking for features which exist in only one of the shells.

I am curious whether there is a standard expected behavior and whether it is considered bad practice when creating more than one account on Linux/Unix that have the same UID. I've done some testing on RHEL5 with this and it behaved as I expected, but I don't know if I'm tempting fate using this trick.

As an example, let's say I have two accounts with the same IDs:

a1:$1$4zIl1:5000:5000::/home/a1:/bin/bash
a2:$1$bmh92:5000:5000::/home/a2:/bin/bash

What this means is:

• I can log in to each account using its own password.
• Files I create will have the same UID.
• Tools such as "ls -l" will list the UID as the first entry in the file (a1 in this case).
• I avoid any permissions or ownership problems between the two accounts because they are really the same user.
• I get login auditing for each account, so I have better granularity into tracking what is happening on the system.

So my questions are:

• Is this ability designed or is it just the way it happens to work?
• Is this going to be consistent across *nix variants?
• Is this accepted practice?
• Are there unintended consequences to this practice?

Note, the idea here is to use this for system accounts and not normal user accounts.