char * Tcl_GetCwd(interp, bufferPtr)
These procedures may be used to manipulate the current working directory for the application. They provide C-level access to the same functionality as the Tcl pwd command.
Tcl_GetCwd returns a pointer to a string specifying the current directory, or NULL if the current directory could not be determined. If NULL is returned, an error message is left in the interp's result. Storage for the result string is allocated in bufferPtr; the caller must call Tcl_DStringFree() when the result is no longer needed. The format of the path is UTF-8.
Tcl_Chdir changes the applications current working directory to the value specified in path. The format of the passed in string must be UTF-8. The function returns -1 on error or 0 on success.