Mac OS X 10.4: Screenshot default format...

One of the most annoying things about taking a screenshot with the old Command + Shift + 4 key equivalent in OS X 10.4 is the fact that the file format now defaults to .png [previous OS versions defaulted the screenshot file to PDF format].  For several years now, I've been typing Command + Shift + 4, then finding and opening the .png on the desktop and then re-saving it as a .jpg file.  What a hassle.

I was just looking around online for a solution to this age-old problem as I've done in the past on more than one occasion but this time around, I found a really nifty little trick via a comment to a post on Macintouch.  It requires the faint-of-Mac-OS-X-hearted to find and launch the Terminal application in Applications>Utilities and enter some archaic command line text into it but after that, screenshots are saved in whatever format you choose, provided of course that it's supported by QuickTime, according to the Macintouch post [.png, .jpg, .pdf and possibly .bmp, etc.].

Launch the Terminal application in the Applications>Utilities folder and paste in the following text [don't hit Enter after pasting the text and don't copy the carriage return after the text or pasting it to the Terminal app will submit the command prematurely]:

defaults write com.apple.screencapture type

Now, at the end of the line you pasted in from the text above enter a single space and then "jpg", "png" or "pdf" without the quotes.  Here's some examples of how it would look for three different file formats:

defaults write com.apple.screencapture type jpg

or...

defaults write com.apple.screencapture type png

or...

defaults write com.apple.screencapture type pdf

When you've got the line configured with the appropriate three character type definition at the end, hit Enter to submit the change to the default file type.  After submitting the change, you need to log out and back in.  After logging back in again, give the Command + Shift + 4 screenshot trick a whirl.  The file format of the resulting screenshot file will be whatever you specified with the last three characters in the Terminal app as mentioned above.  This was verified by me when after logging back in, I typed Command + Shift + 4, dragged a box around some small portion of my desktop, released the mouse and a file that ended in .jpg appeared on my desktop. 

For me, this is a huge timesaver when reporting bugs.  Your mileage may vary.  You can thank me later.