I have ST2 setup so that I can do \'sublime file.txt\' and it will open in a ST2 window. But how can I make it open in a new tab in the currently open window?
Try Sublime command line help
subl --help Sublime Text 2 Build 2217
Usage: subl [arguments] [files] edit the given files
or: subl [arguments] [directories] open the given directories
or: subl [arguments] - edit stdin
Arguments:
--project : Load the given project
--command : Run the given command
-n or --new-window: Open a new window
-a or --add: Add folders to the current window
-w or --wait: Wait for the files to be closed before returning
-b or --background: Don't activate the application
-s or --stay: Keep the application activated after closing the file
-h or --help: Show help (this message) and exit
-v or --version: Show version and exit
--wait is implied if reading from stdin. Use --stay to not switch back
to the terminal when a file is closed (only relevant if waiting for a file).
Filenames may be given a :line or :line:column suffix to open at a specific
location.
After you have opened a new window the subsequent files should be added there as per the default behavior.