SFTP also supports PWD

docs/libcurl/curl_easy_setopt.3

@@ -848,7 +848,7 @@ to append strings (commands) to the list, and clear the entire list
 afterwards with \fIcurl_slist_free_all(3)\fP. Disable this operation
 again by setting a NULL to this option.
 The valid SFTP commands are: chgrp, chmod, chown, ln, mkdir,
-rename, rm, rmdir, symlink. (SFTP support added in 7.16.3)
+rename, rm, rmdir, symlink, PWD. (SFTP support added in 7.16.3)
 .IP CURLOPT_POSTQUOTE
 Pass a pointer to a linked list of FTP or SFTP commands to pass to the
 server after your ftp transfer request. The linked list should be a