From Novice to Master, and Back Again

January 14, 2013

In 1985, I was a freshman at St. Olaf College in Minnesota. The college had a VAX 11/780 running 4.2BSD and a PDP-11/70 running v7 with some Berkeley and local code hacked in. It was my first experience with multi-user systems other than dialing into an MS-DOS BBS or two.

The college’s Academic Computing Center had printouts of the 4.2BSD manuals, plus some home-grown documentation, available for sale so students could learn how to use UNIX. One week I sat in the Science Center terminal room and started going through the alphabetical list of the commands available on the VAX, trying each one and reading its man page to learn what it did.

Eventually I got to “su”. “Become the super-user”? What’s that? Does it involve wearing a cape? Sounds interesting, so I tried it. To my disappointment, it just asked for a password, and wouldn’t do anything.

Shortly thereafter, someone came running into the room and asked, “Are you David MacKenzie? Did you just run ‘su’?” “Yeah… what does it do?” “Uh, don’t do that.” My failed “su” attempt had been logged on the system console and one of the sysadmins was worried about an attempted breakin.

Within a year, I did have root access on the VAX, as I learned enough to be hired as a student system programmer. I contributed to upgrading the machine to 4.3BSD when that was released.

Recently I was working on a CentOS Linux virtual machine and needed to look up the command-line options to “su”. I had worked for the past several years mostly on Macs where “sudo” is preferred, so my “su” skills were rusty. I ran “man su” and got the information I needed. Then at the bottom of the screen I sheepishly read “Written by David MacKenzie.”

In the 1990s, while filling in gaps in the GNU toolset, I wrote the GNU “su”, and I had forgotten about it. It’s still what Red Hat and other distributions are shipping.

At least I know what it does now.

Migrating Firefox

June 18, 2012

This is the procedure I use when migrating someone who uses Firefox to a new computer or rebuilding their computer. This works on both Windows and Mac.

  1. Backup their bookmarks. There used to be a bookmarks.html file you could copy from the Firefox profile, but now they’re in a database so you need to export them.
    1. From the Bookmarks menu, select Show All Bookmarks. This pops up a Library window.
    2. In the Library window, from the rightmost pulldown menu (with a star on it), select Backup and put the file on a network drive or removable drive. This backs up the bookmarks to a “JSON” file.
  2. Backup their saved login/passwords.

    1. From the Tools menu, select Add-ons.
    2. On the left, click Get Add-ons. In the “Search all add-ons” box in the upper-right, type “password exporter”.
    3. Find Password Exporter in the list of search results and click the Install button next to it.
    4. Go to Preferences (Mac) or Tools>Options (Windows), Security tab.
    5. Click the “Import/Export Passwords” button added by the Password Exporter add-on.
    6. Click the “Export Passwords” button and put the file on a network drive or removable drive. This backs up their logins and passwords to an XML file.
  3. Then, on their new computer, use similar procedures, except select Restore in the Library window menu and “Import Passwords” in the Import/Export window.

How Not to Build a Fence

April 1, 2012

Three years ago, we hired Capital Fence to replace the deteriorating old fence around our yard. They’re a popular fence company here in the DC/MD/VA area, so I assumed they’d do a reasonable job. It wasn’t until they were building the fence that I learned that

  1. They just stick the posts in the ground, with no concrete or other means of keeping them from heaving seasonally, and
  2. They use nail guns, not screws, to put the fence together.

The result? Within a year, I was having to make repairs to our new fence because of warping boards pulling out the nails and heaving gate posts pulling the gate so far out of alignment that the lock wouldn’t open. Buyer beware: ask detailed questions before signing a contract. Even if they are a big name. I couldn’t imagine that professionals would use such poor construction methods, but by the time I found out it was too late.

Here are some closeups of our three year old fence. I’ve got some work ahead of me driving in deck screws to pull it back together.

Here are some examples of warping boards pulling the nails out.
Warping board pulling out on top
Warping top board

Boards pulling apart

Boards warping at the bottom

Here is a closeup of the gate lock showing the original top screw hole above the lock. I had to drill new holes because the post sank so much that the lock no longer lined up.
Gate lock misalignment due to sinking

Here’s their sign on this shoddy work.
Logo of fence company to avoid


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