We recently upgraded from Centos 4.3 to 5.9 and have come across a perplexing condition with regard to a very few direct-character printers we use. Since the beginning of Unix we have placed a command nohup sleep 1024000
Now, with Centos 5.9 Linux 2.6.18-348.6.1.el5xen #1 SMP Tue May 21 16:10:52 EDT 2013 x86_64 x86_64 x86_64 (on a Proliant server) we find the sleep is in place but the ending characters get truncated as if the port is in fact closed.
Interestingly on 4.3 the command /sbin/fuser /dev/ttyUSB0 would produce the PID of the sleep, but on 5.9 it does not. As an experiment, I rebooted the system and ran the following command on one port cat - </dev/ttyUSB0 and on another I typed /sbin/fuser /dev/ttyUSB0 and again the process id of my running port is not reported.
Yes, there are 100 other ways to process the print output, but anything the USED to work and suddenly STOPS working requires an explanation
Did I miss something in a README somwhere?