Ever since I installed Snow Leopard, I've been dealing with a particularly annoying bug. Terminal keeps forgetting my shell preferences.

I generally prefer to use tcsh rather than bash. This is mostly because I'm a technological dinosaur. I also have a lot invested into my ancient and extensive .cshrc that has taken years to grow and develop.

Normally, I set the default shell inside the Terminal app preferences. But there's a problem. Snow Leopard keeps losing my preferences for reasons I do not begin to understand. With this Snow Leopard bug, I had to find another approach for choosing my shell. Terminal preferences were no longer going to work for me.

There are actually two very good ways to handle this problem.

First, there's chsh, as pointed out by Richard Buckle and Brian "Shmit" this morning. A command line utility, chsh edits the OS X user database, allowing you to change a user's default shell. chsh is built into OS X, and you can pull up a man page to read details about its use. Supply the shell you want to use, authenticate, and you're set. There is, however, an easier solution.

It's System Preferences. As Bill Bumgarner and Jordan Breeding reminded me today, you can access advanced user settings by right-clicking (or Ctrl-clicking) a user name in the Accounts settings; then choose Advanced Options. (Please note that you must first unlock the settings before this trick becomes available.)

When selected, an Advanced Options screen appears. You can set the new login shell in this screen. A simple pop-up list offers easy access to all installed shells. Select the one you want to use and, once selected, click OK to dismiss the screen and return to the Accounts settings pane.

This solution works a lot better than the bash .profile approach I had been using for a few weeks. Running tcsh through the .profile initialization file had caused an extra layer of interaction each time I wanted to close a terminal window. The application warned me that I was about to kill a running process (i.e. my tcsh subprocess). Changing my default shell meant I could create and close windows on demand without that extra dialog, a welcome respite.

In conclusion, while I'm not sure why Terminal keeps losing its preferences, I'm pleased that I at least learned a way to bypass the shell issue. Hopefully, Apple will get this bug fixed soon.

When I shared an AppleScript last week which created randomized signatures using TextExpander, I promised to revisit it when the iheartquotes.com API started working again. It's working right now, but it seems to go up and down; check this link before you try the script and make sure you get a quote, not an error message.

As before, when used with a TextExpander snippet set to the AppleScript type, this script will provide a random quote, this time pulling it from the Internet rather than our own list. The script is essentially the same, so I'm only going to explain the part which changed; visit the previous article for a rundown on the rest:

set _date to do shell script ¬
 "date +'Sent on %A, %b %d at %l:%M %p'|tr -s ' '"

 set _quote to ""

 try

 set _quote to do shell script "curl -s \\
 'http://www.iheartquotes.com/api/v1/random?source=macintosh&max_lines=4'"

 set {astid, AppleScript's text item delimiters} ¬
 to {AppleScript's text item delimiters, return}
 set _quote to paragraphs 1 through -3 of _quote as string
 set AppleScript's text item delimiters to astid

 end try

 set _out to "
 -Brett

 " & _date & "
 ________________________________
 Brett Terpstra | myemailaddress@mywebsite.com
 The Unofficial Apple Weblog | http://www.tuaw.com

 " & _quote

 return _out

The curl call

Here's the part which makes this more interesting than it was before:

set _quote to do shell script "curl -s \\
 'http://www.iheartquotes.com/api/v1/random?source=macintosh&max_lines=4'"

First off, that really should be all one line, but is split here for formatting purposes. You can remove the double backslash (\\) and merge the lines together if you like. What this does is use AppleScript's ability to run shell scripts (Unix commands) to make a curl call to retrieve a response from the iheartquotes API. Note the "try" statement surrounding that section; it will just return our regular signature without the quote if anything goes wrong. If it gets a response, it stores it in a variable (_quote) and then trims off the last line, like this:

set {astid, AppleScript's text item delimiters} ¬
 to {AppleScript's text item delimiters, return}
 set _quote to paragraphs 1 through -3 of _quote as string
 set AppleScript's text item delimiters to astid

The first two lines (actually one line) are shorthand for setting "AppleScript's text item delimiters" -- the character that AppleScript uses to separate text items in a block of text -- to the return character and store the current text item delimiter in a variable so we can restore it with the last line. Using the paragraphs command, which automatically uses the return key to separate paragraphs, we turn the quote into a list of paragraphs, starting with the first and ending with the third from last. This is because the last two "paragraphs" are always an empty line and a permalink (even if you use the API's parameters to turn off the permalink). The last part of that line, "as string", is where the text item delimiters come into play, putting the list items back together with a return after each one, reconstructing the original formatting.

Note: You could do the same thing by adding |sed -n '$!p' to the end of the do shell script line, right before the last double quote. I suppose you might as well, as long as you're dipping out to the shell anyway ...

From there it's the same as before, just building a final output string from the pieces we've created. This method provides a much wider variety of randomized signatures than constructing your own list by making use of a small section of the wide array of data on the interwebs. The use of curl in an AppleScript can open a lot of possibilities, such as posting to Twitter in various ways. or shortening urls on the fly. Have fun.

This month's MacTech magazine offers a feature article by Edward Marczak on using dsh, the "dancer's shell" or distributed shell utility, to batch-administer machines in a single blast without having to hit each one, or use a pricey management tool such as ARD or LANrev. Although dsh isn't included with Mac OS X or available as a binary or port build, it does compile cleanly on the Mac and should work well out of the box.

The idea behind dsh is to take a list of targets (machines you can reach via SSH), and run a command or extended script on all of them at once. This is functionality that's wrapped up in a nice GUI in Apple Remote Desktop; it's deeply powerful and very handy. Supposing you wanted to check the uptime for a bunch of your lab boxes -- manually, you'd have to run around, or SSH to each one and run the 'uptime' command. With dsh, you make your machine list (optionally, loading your SSH public key on the machines ahead of time to avoid password prompts) and run one command:

dsh -Ma uptime

Very handy. The full article isn't online yet, but it's worth seeking out a copy of the magazine if you're interested in automation of enterprise Mac admin tasks.

DTerm is a utility just released by Decimus Software Inc. It's a Leopard-only app that provides a hotkey-triggered HUD which allows shell commands to be run from anywhere in OS X. In case you're wondering why, just imagine what less window switching and screen clutter could mean for productivity on jobs that require both Finder and Terminal. Yes, you can do a lot with Quicksilver, but DTerm provides bash name completion with a dropdown, context sensitivity to your current path and full output with clipboard features. You can also type ?-? in the HUD to run the command in the Terminal, which will open up to your current path.

DTerm is all about reducing effort, really. The process of running a command in the current directory is reduced to just a few keystrokes and there's no need to grab the mouse or switch to another application. Better Path Finder integration would be nice, but the developers tell me that it's Path Finder's own use of the Accessibility system that prevents that right now.

DTerm requires Leopard and has a free demo (up to 50 commands) after which the program costs $20. Visit the DTerm page for the download and more info, including a speedy video that will satisfy your secret bash-voyeurism fetish and won't waste much of your time.

Erica mentioned mdfind a little while ago. It's not a brand new tool, but there hasn't been a great deal of discussion surrounding it. For shell scripters and Terminal junkies, it's a goldmine of search goodness that can make you never want to key out find . -name "letsgogetcoffeewhilewewait.rb" or even locate didcronupdatethedb.yet again.

There are two mdfind options mentioned at Mac OS X Hints that are worth a mention, one found only in the man page, and one found only in the usage info. The former being "-interpret", which allows the advanced Spotlight query syntax to be used on the command line as if typed into the Spotlight window, turning mdfind "kMDItemContentType == 'public.jpeg'" into mdfind -interpret "kind:jpeg". Its opposing force would be "-literal", which forces a literal interpretation of the query string. Any qualified Spotlight query should be usable with "-interpret", so go ahead with mdfind -interpret "kind:image flash:1 modified:<=1/1/08 ex-girlfriend" to find those late-night pictures of last year's special someone. That would take a lot of metadata work to pull off without "-interpret".

The second option mentioned isn't in the man page, but you'll see it in the usage info if you run mdfind with no parameters. It's the "-s" option that loads saved searches. It will look in ~/Library/Saved Searches unless a path is specified. So you can save a search in Spotlight called "PDFs from yesterday" and run mdfind -s "PDFs from yesterday" to launch the same search at the command line. See, I had to throw a "normal" search in there to keep you on your toes.

Terminal jockeys can mix these up with a few pipes, stir in some perl and sprinkle in a little awk to get some really great Spotlight soufflé. Of course, if you don't like the command line and you're still reading this, you're a downright hardy trooper and I commend you. Go have a cup of coffee, you deserve it.

[via Mac OS X Hints]

Over at the #iphone channel at irc.osx86.hu, the thoroughly awesome NerveGas has figured out how to enable ssh on the iPhone without using restore mode. The secret lies in overwriting an existing binary and plist to trick the iPhone into calling chmod on the Dropbear ssh server and making it executable.

At this time, NerveGas has used Nightwatch's compiler to create iPhone-compatible versions of curl and ps as well as a number of other useful Unix utilities. (He's working on grep, as I write).

So what does this mean? Well, once you've got ssh installed on your iPhone and active, you can access your iPhone from a shell on your Mac. You can send and retrieve files using scp or sftp. And you can use the compilation toolchain to build other Unix utils or even your own software. It's just a short matter of time until perl and other command-line utilities are iPhone-ready.

Have you ever lost track of a file that you were just working on? Or were you ever curious about which files an installer has just added or modified? The command line find command offers a simple way to track down any files created or updated within the last few minutes. Its amin and cmin flags tells find to locate files that changed with a certain number of minutes, e.g. to search within 10 minutes: find / -cmin -10 or find /Users/ericasadun/ -amin -3. The - before the time says to find within the time period (with, say, the last three minutes) rather than to look for exact time matches (at 3 minutes ago exactly).