There's a cwd
symlink in every process' /proc
folder, but as a commoner you wouldn't have any rights to read any other's proc folder - only your own:
[marc@panic home]$ ls -l /proc/$$/cwd
lrwxrwxrwx. 1 marc marc 0 May 5 12:06 /proc/16257/cwd -> /home
^^^^^---cwd
[marc@panic home]$
^^^^---cwd