Python 2.4 is included with the FreeBSD base system. If you need to, you can replace 2.4 with version 2.5 from the Ports tree in the /usr/ports/lang/python25/ directory. To set the new version to the default, symlink the new executable to the generic name: ln -s /usr/local/bin/python25 /usr/local/bin/python
Automation and Reporting
What good is an operating system if it can't perform automated tasks and create readable feedback that shows system activities? FreeBSD offers nothing above what most other Unix-like operating systems provide in these areas, so if you already have some experience with cron and syslog, you can probably skip this section— there's nothing new for you here.
The Cron Daemon
The cron implementation in FreeBSD is Vixie-cron, and is configured with the crontab command. Rather than reprint the information in the cron and crontab man pages, this guide will direct you to them.
The cron time format is as follows: minutes, hours, days, months, and day of the week. It also accepts plain English time formats such as @hourly, @daily, @weekly, @monthly, and @yearly. If you need something more specific or more frequent than hourly, you need to put your cron job into the aforementioned time format.
Packet filtering is a network security mechanism that
works by controlling what data can flow to and from a network.
The basic device that interconnects IP networks is called
a router. A router may be a dedicated piece of
hardware that has no other purpose, or it may be a piece of software
that runs on a general-purpose computer running Unix, Windows NT, or
another operating system (MS-DOS, Windows 95/98, Macintosh, or other).
Packets traversing an internetwork (a network of networks) travel from
router to router until they reach their destination. The Internet itself
is sort of the granddaddy of internetworks the ultimate "network of
A router has to make a routing decision about each packet it
receives; it has to decide how to send that packet on towards its
ultimate destination. In general, a packet carries no information to
help the router in this decision, other than the IP address of the
packet's ultimate destination. The packet tells the router where it
wants to go but not how to get there. Routers communicate with each
other using routingprotocols
such as the Routing Information Protocol (RIP) and Open Shortest Path
First (OSPF) to build routing tables in memory to
determine how to get the packets to their destinations. When routing a
packet, a router compares the packet's destination address to entries in
the routing table and sends the packet onward as directed by the routing
table. Often, there won't be a specific route for a particular
destination, and the router will use a defaultroute; generally, such a route directs the packet
towards smarter or better-connected routers. (The default routes at most
sites point towards the Internet.)
This chapter looks at some of the more advanced features of MapReduce,
including counters and sorting and joining datasets.
There are often things you would like to know about the data
you are analyzing but that are peripheral to the analysis you are
performing. For example, if you were counting invalid records and
discovered that the proportion of invalid records in the whole dataset was
very high, you might be prompted to check why so many records were being
marked as invalidperhaps there is a bug in the part of the program that
detects invalid records? Or if the data were of poor quality and genuinely
did have very many invalid records, after discovering this, you might
decide to increase the size of the dataset so that the number of good
records was large enough for meaningful analysis.
Counters are a useful channel for gathering statistics about the
job: for quality control or for application-level statistics. They are
also useful for problem diagnosis. If you are tempted to put a log message
into your map or reduce task, it is often better to see whether you can
use a counter instead to record that a particular condition occurred. In
addition to counter values being much easier to retrieve than log output
for large distributed jobs, you get a record of the number of times that
condition occurred, which is more work to obtain from a set of
Leaders as Teachers: Facilitating individual Learning, Growth, and Development
Many view the quality of relationships in an organization as the foundation for its accomplishments and success. In schools, as in other organizational settings, the culture that develops as an expression of these dynamics is a central determining factor of the school’s ability to improve and thrive. Bolman and Deal (1997) identify culture as one of the “wellsprings of high performance” in high-performing groups (p. 261). Martin-Kniep (2008) cites research suggesting that culture can create the conditions for people to act courageously and exercise initiative without fear of retribution or ridicule. Wagner et al. (2006) Define culture as “the shared values, beliefs, assumptions, expectations, and behaviors related to students and learning, teachers and teaching, instructional leadership, and the quality of relationships within and beyond school” (p. 102). Culture, they say, represents the “invisible and powerful meanings and mindsets held individually and collectively throughout the system” (p. 102).