osx - Determine OS X keyboard layout ("input source") in the terminal/a script? -

i determine os x keyboard layout (or "input source" os x calls it) terminal can show in places tmux status bar.

so want know if current layout "u.s." or "swedish - pro" example.

googling turns nothing me. possible?

note: @marksetchell deserves credit coming fundamental approach - [start to] , tools use. after further investigation , , forth in comments thought i'd summarize solution (as of os x 10.9.1):

do shell script "defaults read ~/library/preferences/com.apple.hitoolbox.plist \\  appleselectedinputsources | \\  egrep -w 'keyboardlayout name' | sed -e 's/^.+ = \"?([^\"]+)\"?;$/\\1/'" 

• the selected keyboard layout stored in user-level file ~/library/preferences/com.apple.hitoolbox.plist, top-level key appleselectedinputsources, subkey keyboardlayout name.
• defaults read ensures current settings read (sadly, of osx 10.9, otherwise superior /usr/libexec/plistbuddy sees cached version, may out of sync).
• since defaults read cannot return individual key's value, value of interest must extracted via egrep , sed - 1 caveat there defaults read conditionally uses double quotes around key names , string values, depending on whether single word (without punctuation) or not.

update:

turns out applescript can parse property lists, it's bit pulling teeth. also, incredibly, potentially-not-fully-current-values problem affects applescript's parsing.

below applescript handler gets current keyboard layout; uses do shell script-based workaround ensure plist file current, otherwise uses applescript's property-list features, via property list suite of application system events.

note: obviously, above shell-based approach shorter in case, code below demonstrates general techniques working property lists.

# example call. set activekbdlayout getactivekeyboardlayout() # ->, e.g., "u.s."  on getactivekeyboardlayout()    # surprisingly, using posix-style paths (even '~') works    # `property list file` type.   set plistpath "~/library/preferences/com.apple.hitoolbox.plist"    # !! first, ensure plist cache flushed ,   # !! *.plist file contains current value; executing   # !! `default read` against file - dummy   # !! key - that.   try     shell script "defaults read " & plistpath & " dummy"   end try    tell application "system events"      repeat pli in property list items of ¬       property list item "appleselectedinputsources" of ¬       property list file plistpath       # (first) entry key "keyboardlayout name" , return       # value.       # note: not entries may have 'keyboardlayout name' key,        # must ignore errors.       try         return value of property list item "keyboardlayout name" of pli       end try     end repeat    end tell end getactivekeyboardlayout