I mean to find out what it is doing at the point that it is hung.
Yep. Not had a change to compile up CUPS w/ debug yet [I'll see if I get anything out of it w/ the normal build though]. Still not exactly sure what starts this backend proc. off, as it's not always there at start-up; I do have it sometimes w/out printing so it's not (just) that.
FWIW, this is what strace gives me [edited] when I attach it to a backend that should have gone away:
open("/dev/ttyS1", O_WRONLY|O_NONBLOCK|O_NOCTTY) = 0
close(0) = 0
...
open("/dev/ttyS31", O_WRONLY|O_NONBLOCK|O_NOCTTY) = 0
close(0) = 0
open("/dev/ttyS32", O_WRONLY|O_NONBLOCK|O_NOCTTY) = -1 ENOENT (No such file or directory)
open("/dev/ttyS33", O_WRONLY|O_NONBLOCK|O_NOCTTY) = -1 ENOENT (No such file or directory)
...
open("/dev/ttyS99", O_WRONLY|O_NONBLOCK|O_NOCTTY) = -1 ENOENT (No such file or directory)
open("/dev/usb/ttyUSB0", O_WRONLY|O_NONBLOCK|O_NOCTTY) = -1 ENODEV (No such device)
...
open("/dev/usb/ttyUSB15", O_WRONLY|O_NONBLOCK|O_NOCTTY) = -1 ENODEV (No such device)
write(1, "serial serial:/dev/ttyS0?baud=11"..., 2093) = -1 EPIPE (Broken pipe)
--- SIGPIPE (Broken pipe) @ 0 (0) ---
munmap(0x40031000, 4096) = 0
exit_group(0) = ?
-- [neil@xxx ~]# rm -f .signature [neil@xxx ~]# ls -l .signature ls: .signature: No such file or directory [neil@xxx ~]# exit
