Subj : Re: Javascript restriction in Trixie To : All From : Theo Date : Tue Dec 09 2025 11:21:24 Theo wrote: > bp@www.zefox.net wrote: > > [apologies for the wide lines] > > > > Theo wrote: > > > > > > Depending on what kind of device it appears as (serial, keyboard, mass > > > storage, network, ...) see if you can work out what other app might have > > > grabbed it. ('sudo lsof' is handy here, if it appears as a device node that > > > you can grep for) > > > > Sudo lsof is loquatious, but not obviously informative. These tests were > > on a Pi5 running up-to-date Bookworm, but the behavior is outwardly the > > same as Trixie on Pi2. > > What I'm looking for is something having grabbed the USB device. This is > hard to specify without knowing how the OWON does its USB, but for example > if it was serial I'd 'lsof | grep /dev/tty' and look for things using the > /dev/ttyUSB0 or /devttyACM0 device the OWON probably uses. > > Since the OWON app has failed to grab the USB you're looking for other apps > that have grabbed it, ie not at the OWON app. Another debugging trick is to run your app under strace: strace -ft -o strace.log That outputs a huge logfile which takes a bit of picking through. What you're looking for is when it tries to access the USB nodes and fails. Maybe that gives some clues as to where the error is coming from. eg strace -ft -o strace.log picocom /dev/ttyUSB0 has a lot of stuff but it says: 15875 11:16:22 openat(AT_FDCWD, "/dev/ttyUSB0", O_RDWR|O_NOCTTY|O_NONBLOCK) = -1 ENOENT (No such file or directory) 15875 11:16:22 write(2, "\r\nFATAL: ", 9) = 9 15875 11:16:22 write(2, "cannot open /dev/ttyUSB0: No suc"..., 51) = 51 15875 11:16:22 write(2, "\r\n", 2) = 2 15875 11:16:22 exit_group(1) = ? 15875 11:16:22 +++ exited with 1 +++ which tells me it couldn't open the /dev/ttyUSB0 device because it doesn't exist, and then puts a FATAL message on the console. This error is correct because I have no USB serial devices plugged into this machine. Theo --- PyGate Linux v1.5.2 * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10) .