You can take a screen shot from a command line interface (CLI) on a Mac OS X system by using the
screencapture command.
The screen capture program is located in /usr/sbin. You can
see the available options by using screencapture -h; the
-h option isn't a valid option for the application, but it
will cause the app to print the options it does accept.$ which screencapture
/usr/sbin/screencapture
$ screencapture -h
screencapture: illegal option -- h
usage: screencapture [-icMPmwsWxSCUtoa] [files]
-c force screen capture to go to the clipboard
-C capture the cursor as well as the screen. only in non-interactive modes
-d display errors to the user graphically
-i capture screen interactively, by selection or window
control key - causes screen shot to go to clipboard
space key - toggle between mouse selection and
window selection modes
escape key - cancels interactive screen shot
-m only capture the main monitor, undefined if -i is set
-M screen capture output will go to a new Mail message
-o in window capture mode, do not capture the shadow of the window
-P screen capture output will open in Preview
-s only allow mouse selection mode
-S in window capture mode, capture the screen not the window
-t<format> image format to create, default is png (other options include pdf, jpg, tiff and other formats)
-T<seconds> Take the picture after a delay of <seconds>, default is 5
-w only allow window selection mode
-W start interaction in window selection mode
-x do not play sounds
-a do not include windows attached to selected windows
-r do not add dpi meta data to image
-l<windowid> capture this windowsid
-R<x,y,w,h> capture screen rect
files where to save the screen capture, 1 file per screen
$By default, a screenshot will be stored in PNG format, but you can select
other formats with the -t (lowercase "t") option. You can
specify that you want to use PDF, JPG, or TIFF, instead. You can use the
-T (uppercase "T") option to specify a delay in seconds
between the time the command is issued and the time the screen shot
is taken, which gives you the opportunity to switch to another window
to have a screenshot taken of it. The advantage of screenshot over the
GUI Preview program
found in the Applications folder for taking a picture of a window is
that with Preview sometimes pulldown menus will disappear from a window
when you switch to Preview to take a screen shot. With screencapture,
you can issue the command with a delay, the default is 5 seconds, switch
to the relevant window, select the menu or other option, and then wait
the number of seconds specified for screencapture to capture the contents
appearing in that window at that time. E.g., the command below will wait
10 seconds to take a snapshot of what is appearing on a window that is
the current one when 10 seconds elapses.
$ screencapture -T 10 grayed.png libpng warning: zero length keyword libpng warning: Empty language field in iTXt chunk $
You won't see any indication that the screen capture occurred, so you need to just wait until the specified time has elapsed before looking for the output file, which will be placed in the current directory from which you issued the command if you didn't specify a path, but only the file name. The "libpng warnings" don't indicate that the screen shot couldn't be taken; the output file specified is a valild PNG file.
