How to get current dir?

There is a program. Command Prompt. It is necessary to put in place PATH, a current path.

os.loadAPI("/root/bin/API")
term.setBackgroundColor(32768)
API.clear()

while true do
term.setTextColor(16384)
write(".")
term.setTextColor(1)
textutils.slowWrite(" PATH ", 50)
a=read()
shell.run(a)
end

shell.dir().