api - How does getcwd work in Linux? -

i make directory in urxvt:

$ mkdir /tmp/mydir 

then

$ cd /tmp/mydir 

then run second copy of urxvt , do:

$ rm -r /tmp/mydir/ 

i close second copy of urxvt , switch first copy of urxvt , do:

$ pwd /tmp/mydir 

pwd coreutils v 2.21-2 uses getcwd working directory. how getcwd working directory deleted?