This requires imagemagick to be installed on the machine. Open up a terminal, cd
into the folder with the PNG files and run:
ls -1 *.png | xargs -n 1 bash -c 'convert "$0" "${0%.*}.jpg"'
iTerm for Mac has a broadcast feature that allows for input to be broadcast to all panes or tabs. This feature can be enabled through the Shell > Broadcast Input
menu in the OS X menu bar. I found the keyboard shortcut Alt + Cmd + I
to be particularly useful. It toggles broadcasting to all panes on and off. The iTerm 2 Beta 3 release also allows for the silencing of the pop-up alert that appears every time the broadcast feature is enabled (warning that input will be broadcast to all panes).