Tcl_CreateCloseHandler(3tcl) on Linux
The text 8c08dc1a964c, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it. The page shows this text now.
arrange for callbacks when channels are closed