cal -3 | cut -c1-16 | grep -v "^ *$" | tail -1 | sed -e 's/^..* \([23][0-9]\)/\1/'
It turns out you need a fairly modern version of the cal command. Darn… perhaps gnu cal will help if your system has an older cal version.

How it works…

cal -3

Gives me three months; the month prior, the month I am in, and the next month.

cut -c1-16

Ignores this month and next month.

grep -v "^ *$"

Ignores any blank lines, note the space between the ^ and the $.

tail -1

Ignores all except the last week of dates.

sed -e 's/^..* \([23][0-9]\)/\1/'

Uses the streams editor to ignore all except the last two digits, and specifically, only the last two that begin with 2 or 3 (all months have 28, 29, 30, or 31 days in them). Note the space preceding the \ character.

We are left with the last day of the preceding month, no matter which month it is now. So… why was I trying to solve this again?

Update: Alan points out that on modern systems with TimeZone features you can actually just have date itself do all the heavy lifting:
TZ=`/bin/date +%Z`
DS=`TZ=${TZ}+24 /bin/date +%m-%d-%y`
echo "Current time `/bin/date +%m-%d-%y`"
echo "One day earlier $DS"
DS=`TZ=${TZ}-24 /bin/date +%m-%d-%y`
echo "One day later $DS"

TZ=`/bin/date +%Z` ; TZ=${TZ}+24 /bin/date +%d


I will try to catch up a little for those who are not inclined to use farcebook…

Some catchup below the fold:

I had a lovely Thanksgiving and then went through a brief period of feeling out of touch with the world because my two jobs are resetting my natural clock and daily rhythm to a schedule that few of my friends share. I have learned that some people don’t mind a late night text and phone call, and for that I am grateful as I can talk to people on my drive home from the 2nd job. With both of us working two jobs, Erci and I are seeing less of each other so we’ve made an effort to have a date night now and then. We got to see the recent Muppet movie, and were delighted by the show, the dance numbers, and the appearance of both Jim Parsons and Neil Patrick Harris.

I once again (and pretty much every quarter) am very grateful to Mike Bombich for Carbon Copy Cloner which makes full backups of your Macs easy and you can boot from them. Highly recommended.

I took advantage of some employee discounts and replaced our original Time Capsule with a new one and our D-Link with an Airport Extreme for much faster wireless throughout the house. I am also replacing the Linux with Xen virtual Open Filer machine iSCSI disk share to an old Mac Mini as home media server with Linux NFS shared directly to newer Mac Mini as Media controller and AppleTV units as Media viewers. This is the sort of thing I find fun!

A lot of my personal project time got stolen when I discovered my 120 gallon marine reef aquarium spring a leak! Jeff Lofgren was my hero and helped me move the fish, shrimp, corals, and other living things to a variety of smaller tanks and coolers the day the leak was discovered, and most everything survived (though I did have one of the smaller tanks crash). I am trying to get the leak repaired so I can put the big tank back together again, but have not had time to really progress on it much.

Discovered that Domaine Raspail-Ay 2008 Gigondas is a spectacular wine while having a lovely dinner out with a special friend, highly recommended. I also found out that Fireworx pizza in Leesburg is delicious for those who can do gluten, thanks to co-workers for dragging me there.

ThinkGeek has some pretty spectacular iPad cases with integrated Bluetooth keyboards.

Cassandra and Jeff recommended and lent us “Across the Universe” and we finally watched it Christmas Day and it is both spectacular and moving. I went out and bought my own copies of both the movie and the soundtrack the very next day and have been listening to it ever since… beautiful dance numbers, some very compelling re-arrangements of Beatles music.

I am trying to get several appliances and home repairs done, and we keep running into no one wanting to pick up work, so I guess the economy must be recovering. I am learning that I despise the incompetence that is Sears Appliance Repair, and the fact that they seem to have bought out all the competition. Our Dacor oven has an F1 code alert, which indicates problem with the control panel. Our Viking under-counter fridge has been out for ages with a failed thermostat. We have a small roof leak over our kitchen. All will get fixed eventually, but it’s like pulling teeth to get people to come take our money and fix things.

I successfully replaced a 5th generation iPod classic hard drive and then sold it to a niece for the cost of the replacement parts, very happy that was so easy. Steve and Ashley helped me bring the 120 gallon tank outside and hose it out, and then my hero Jeff Lofgren and Alexandrea Lynch helped bring it back in on New Year’s Eve… Odd mystery, it did not leak when outside, nervous about filling it without having done a repair…

Jill and Eddie hosted the Molecular Mixology blow-out bash to bring in the New Year at their place and Kate, Erci, and I joined many friends there and had a fantastic time being irresponsible… I discovered that coughing after sipping Pyrat rum over a bonfire can be a mini-fireworks show!

Now I am recovering from a fairly nasty ear/throat virus and then infection… Life is always full of surprises.

When I have one Airport device daisy chained off another, both setting up private NAT networks, they appear in series, correctly reflecting the new topology!

Sadly this is not the case on my iOS 5.0.1 based iPhone 4, it simply shows all the network devices it can see in series regardless of the actual network topology.

I still think it is really cool that a topology map is created at all! Thanks Apple. I guess I am a geek, having fun with networks.

The driver to get off Palm Desktop (which I admit to using less and less lately) is that it is a PowerPC app on Macs that only runs because of Rosetta PowerPC emulation on intel based Macs. Rosetta is not in Lion, so in order to upgrade to Lion I need to replace Palm Desktop.

The Evernote solution looks vastly more attractive and sustainable.

More Offices Let Workers Choose Their Own Devices (NY Times)

Sun tried to do this with thin clients a few years ago, but wireless networking technology was not as robust then, and when the device is tied to a physical cable it does not work as well.

Imagine the improved security if the laptop you used for work never actually had any corporate data on it, but instead only had virtual private network (VPN) links and a thin client to access a virtual desktop in the company data center where all your files and work data lived. If your laptop got stolen, the VPN keys on it could be marked invalid at the server side, and the only loss is the physical laptop – no data lost at all.

Imagine the greater comfort and usability if users could pick their preferred laptop and install the software they liked, because whatever is running on their laptop cannot get to the virtual desktop with their pristine corporate information. Security officers and users both happier and perhaps more productive, and risk analysts are probably jumping for joy.

I’d also wager more people pick Apple and Alienware devices.

MacMost Now 478: Pivot Tables in iWork 09 Numbers

Gary has perhaps the best layman’s explanation of Pivot Tables and how you can effectively accomplish the same result without a separate table using Table Categories in Numbers.

While iWork Numbers doesn’t have true pivot tables, you can get similar results using Table Categories. This feature lets you group data together in various ways to reveal the same summaries that you can get with pivot tables.

Sadly MacMost is still Adobe Flash based, so I had to watch it in Chrome as I disable OS based Flash on my Macs

It occurred to me that it might be worthwhile to share the steps in case others have non-techie relatives who want to make this stuff work.

This procedure is to help someone update their iTunes software on a computer, connect an iPad, and install a couple of basic apps on the iPad so they can see how it is done.

Starting assumptions:

• This is all written for a Macintosh running Leopard or Snow Leopard, I suspect it largely works the same on Windows or Lion as well
• I always set up computers for myself and friends and relatives with an Admin account (for installing software, running updates, and doing backups) that is separate from any user accounts (that are used for everything else). The user accounts do NOT have administrative rights, this forces them to log into Admin separately if they really want to install software and prevents browser hijacking from getting out of hand even with the worst browsers. If you have your regular user account set up with administrative rights, you can skip all the switch user to Admin bits and install things as your regular user id.
• I am assuming that you already have an iTunes account associated with a credit card, which is required even for free stuff as proof of verification at the iTunes store
• I am assuming you already have a Wi-Fi network, if not you will either need one set up or you will need a 3G iPad with a data plan from one of the wireless carriers (AT&T or Verizon).

This is really easy, have fun. If it is not fun, take a break and resume later.

The first time you connect and update your iPad will be the longest sync and the most complexity – do not be discouraged; most of the time simply plugging it in will be enough to do everything you need.

First, update iTunes on the computer you plan to sync your iPad to:

1. Log out of all users other than Admin, and quit all running applications
2. Log into the Admin account and pull down the Apple Menu to “Software Update…”

   Select any updates you want, and make sure iTunes is checked if it is on the list
   I typically select everything on the list
   Activate the install to update your computer, it may need a reboot, that is ok

When your computer is done with the updates it will either reboot, or you can log out of the Admin account and log back in as yourself.

Either way, as your own user account, log in and plug in the iPad using the USB cable it came with.

That will start iTunes automatically and begin a sync operation between iTunes and the iPad.
Go get a cup of tea… the first sync will take a short while.

When the sync is done, iTunes will show a new DEVICE in the left hand side navigation bar; it will be the name of your new device – which is probably simply “iPad” until you name it. Mine happens to be named Thoreau, but you can chose anything you like.

Click the device name “iPad” twice to change it’s name to anything you like.

Click just once to select the iPad and the main iTunes window changes to a summary of the iPad’s software. Click the tab at the top labeled “Info” to see the iPad version, memory, size…

In the Version section, click the “Check for Update” button, if an update is available, go ahead and download and install it. Grab another cup of tea, this will take a long while as well.

Once both iTunes on your computer and iOS on your iPad are up to date, now we configure what gets put on your iPad with each sync operation.

Click the Device Name again, then the Info Tab. Scroll down the window and…

• If you want Address Book contacts from your Mac shared with the iPad – make sure to check Sync Address Book Contacts
• If you want iCal calendars from your Mac shared with the iPad – make sure to check Sync iCal calendars
• If you want Mail Accounts from your Mac shared with the iPad – make sure to check Sync Mail Accounts
• Are you using Safari on you Mac as a web browser? If so, click Sync Safari bookmarks too

I recommend all four – though it means anyone with access to your iPad can see those things too – which is probably fine unless a lot of people have access to your iPad when you are not around

I suggest you sync all Music, Movies, TV Shows, Podcasts, Books, and Photos too – though you may run out of space. If you do – that’s ok – just turn off syncing of some of those things that you are not likely to use on the iPad first until there is enough space. Photos are REALLY handy to have on the iPad – I’d keep them synced the longest if you can.

Now the real fun begins, let’s grab a couple of apps. This is something you will be doing a lot of, and it much easier than everything you have done so far.

I’d stick to free for the moment… unless there is something you REALLY want.
Most Apps are cheap (99 cents to $9.99) – but why spend if there are free things out there?

In iTunes, click on the iTunes Store (should be four up from your iPad device on the left hand listing).
That goes to Apple and brings up their iTunes Store.
You may need to sign in with your iTunes Store account – I am pretty sure you already have one.
Music is the default storefront; but for the iPad we want Apps. Click the App Store tab.
It has two store fronts… iPhone and iPad – click the iPad one (though iPhone apps will work too).
Note the Search Store field in the top-right hand corner…

That is a VERY USEFUL thing. The Apple iTunes Store is a horrible place to browse… sadly… I much prefer reading about stuff online and then searching for them using that Search Store field.

Search for Pocket Pond HD
You should get three or four apps, that match that search. One should be Pocket Pond HD for free. Click the “Free” button (the word itself is the button).

That should begin your “purchase” (of $0.00) and download of that App to your iMac. You may need to login to iTunes Store again to prove you are you and not someone else.

While Pocket Pond HD is downloading, start a second search: iBooks
Once again there are two sets of apps, iPhone and iPad – click the Free button next to the iPad one.

While iBooks is downloading, start a third search: iPad User Guide for iOS 4.3
This is not an app, but is actually a free book that will be read in the iBooks app. Click the “Free” button.

While that book is downloading, start a fourth search: Skype
You will see two sets of apps this time, iPhone and iPad apps – find the Skype for iPad app and click the “Free” button again.

That’s enough to start with. Let them finish downloading.

Once they are done downloading, Right-Click on the iPad device (or whatever you named it to be) and and select Sync from the pop-up menu:

It will take a few moments to Sync.
When it is done, pull the USB cable off both ends.

All the Apps that come with your iPad will be there – but there will be three new ones.
Pocket Pond HD
iBooks
Skype

They may not fit on the first screen, just swipe your fingers right or left to change screens and see more apps.

Tap the Pocket Pond icon to enjoy a hand held Koi pond and sounds of nature… Tap the screen to splash the fish… enjoy. This is a silly app just to show you how to download an app and to interact with the screen a little.

OK – next we need to let your iPad on your home network.

On the iPad – tap the Settings button.

Under Airplane Mode there should a menu for Wi-Fi. Tap that.

Make sure Wi-Fi is on (slide the button until a blue ON appears).

Choose your home Wi-Fi network, and enter it’s password if you need to.
This puts your iPad on the home network. Now things like Mail, Safari, Skype, Maps all work.

Next, tap your iBooks app and open the iPad User Guide book. Read it as much as you like, turn pages by swiping a finger across the screen. This book is free, but not all books are free. iBooks has many free and many paid books that are licensed through Apple.

When you finish that – try out Skype (if you have a Skype account) to call a relative for free.
You can ( but do not have to ) do video phone calls – assuming cameras are at both ends (both your iMac and your iPad have cameras). I tend to only use Skype for text chat (like Adium/AIM) and voice calls – but some like the video call feature.

Other Free Apps to check out:

• BBC News - BBC News
• ABC Player - ABC shows
• NPR - NPR news and Public Radio shows
• The Weather Channel (TWC MAX+) - Weather with Radar Maps and Locale updates
• SoundHound (free version – there are paid ones too) - listens to music you hear play, and tries to “Name that Tune” for you
• Shazam – listens to music you hear play, and tries to “Name that Tune” for you
• The Onion
• Yelp – look up reviews of restaurants nearby
• SnapTell – take a picture of a product, UPC label, or barcode; get price information online
• Gallery – lets you view people’s MobileMe galleries (MobileMe has been shrinking – but will be replaced with iCloud)
• iBooks – lets you read books, magazines, newspapers on your ipad – catch, you still have to buy books from Apple or find free books
• eReader – lets you read books, magazines, newspapers on your ipad – catch, you still have to buy books or find free books or ePub documents
• Nook – lets you read books, magazines, newspapers on your ipad – catch, you still have to buy books from Barnes & Noble or find free books
• Kindle – lets you read books, magazines, newspapers on your ipad – catch, you still have to buy books from Amazon or find free books
• Free Books – lets you read books, magazines, newspapers on your ipad – catch, limited to free books only
• Bookman – lets you read books, magazines, newspapers on your ipad – catch, limited to free books only

So far – all those apps are free. You can add more and buy some as you like.

What is interesting is that this does NOT do what you would think, it actually does The Right Thing(tm) and starts the 7 day view with today, no matter what day it is. Hurray!

The stability, security, performance, and battery life I am enjoying now were not possible on a Flash-enabled machine.

Over-riding DHCP or VPN assigned DNS servers in Mac OS X