Stack trace defined

The code path each thread in a currently existing process traversed to put it in its current state.

Ping sweep with nmap

Need to find a free IP in your address range? Use NMAP to find out which addresses are currently used:

nmap -sP 172.24.17.1-255

"Sharding"

Separating users by servers.

The difference between Red Hat ES and AS versions

Per Red Hat: "ES is licensed for x86 compatible servers with up to 2 CPUs and 8GB of main memory; AS is licensed for servers of any size and any architecture."

ntpdate equivalent command when running NTP service

If your Linux clock is more than a minute or two off, you might be tempted to use the "ntpdate" program to update the clock one time. However, the ntpdate program cannot run while the ntp daemon is running (not to mention the fact the ntpdate function is set to be retired).

You can mimic the functionality of the ntpdate command by issuing the "ntpd -q -g" command. This updates the clock, telling the ntp daemon to ignore the 'sanity limit' of 1000 seconds, and exit after updating the clock.

Where is LVM metadata stored?

You can a backup of your current metadata configuration in /etc/lvm/backup.

Determine Oracle Application Server version

Open the $ORACLE_HOME\config\ias.properties file. Then find the [InstallData] section and the "Version" attribute, which looks like this:

Version=10.1.2.0.0

Oracle version numbers explained

The significance of the version numbers are (lets use 9.0.1.1.2 as an example):

9 is the version number
0 is the new features release number
1 is the maintenance release number
1 is the generic patch set number
2 is the platform-specific patch set number

Cache-Control

I found this excellent listing of Cache-Control definitions on askapache.com:

Cache-Control: no-store
This object may not be stored in any cache, even the requestor’s browser cache.

Cache-Control: no-cache
This object may be held in any cache but it must be revalidated every time it is requested.

Cache-Control: private
This object can be stored in the requesting browser´s cache but not in a shared cache …

Cache-Control: must-revalidate
Tells caches that they must obey any freshness information you give them about an object. The HTTP allows caches to take liberties with the freshness of objects; by specifying this header, you’re telling the cache that you want it to strictly follow your rules.

Cache-Control: proxy-revalidate
Similar to must-revalidate, except that it only applies to proxy caches.

Need a 32-bit package on a 64-bit install?

Steve tells you how to do it here: http://www.phase2.net/?p=51

(For the lazy: Put libgcc.i386 into the %packages section of your kickstart file to install the 32-bit libgcc library)

Ahh, so you CAN install 32-bit Oracle on 64-bit Linux!

Using web server logs to ensure browser caching is working

The first time a browser requests a file, an HTTP code of 200 (request for document) will be written to the web server log. It will look like this:
30.35.127.106 - - [21/Oct/2006:14:38:23 -0700] "GET /OA_MEDIA/FNDREDPT.gif HTTP/1.1" 200 70

The next time the request is received from the browser, it should be served by the browser cache. Thus the entry in the web server log file will be an HTTP code 304 (request for time stamp). It will look like this:

130.35.127.106 - - [21/Oct/2006:14:41:03 -0700] "GET /OA_MEDIA/appslogo.gif HTTP/1.1" 304

Get information about a running module

Use the "modinfo to get information about a running kernel module. For example, here is the results of running the command against the ext3 module:

# modinfo ext3
filename: /lib/modules/2.6.9-42.0.3.EL/kernel/fs/ext3/ext3.ko
author: Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
description: Second Extended Filesystem with journaling extensions
license: GPL
vermagic: 2.6.9-42.0.3.EL 686 REGPARM 4KSTACKS gcc-3.4
depends: jbd