I'm trying to access the parallel port (/dev/lp0) from a non root process. <br><br>Basically I have a program that can only access the port if it runs as root. <br>Here's what happens when I run as root:<br>root@falcon:~/src/k74-
1.0# ./pprxtx all set<br>root@falcon:~/src/k74-1.0# ./pprxtx read<br>255<br>root@falcon:~/src/k74-1.0# ./pprxtx all clear<br>root@falcon:~/src/k74-1.0# ./pprxtx read<br>0<br><br>Here's what happens when I run as a non root user (ed):
<br>ed@falcon:~/src/k74-1.0$ ./pprxtx all set<br>/dev/port: Permission denied<br>ed@falcon:~/src/k74-1.0$ ./pprxtx read<br>/dev/port: Permission denied<br><br>/dev/lp0
I thought that all I had to do was to add my non rootport user to the
device group (lp) in /etc/group and then that user would have
permissions to read and write to that device. <br>lp:x:7:cupsys, ed<br><br>I also changed the device permissions to <br> /dev:<br> crw-rw-rw- 1 root lp 6, 0 2006-09-21 04:56 lp0<br><br>I still can't access the port unless I run as root.
<br><br>If I change the /dev/port (I know,dangerously insecure) permissions to
<br> /dev:<br> crw-rw-rw- 1 root kmem 1, 4 2006-09-21 04:56 port<br><br>I then get: <br>ed@falcon:~/src/k74-1.0$ ./pprxtx read<br>/dev/port: Operation not permitted<br>ed@falcon:~/src/k74-1.0$ ./pprxtx all set<br>/dev/port: Operation not permitted
<br><br>Any ideas? I've done a fair amount of googling this and it seems like I'm doing everything correctly. <br><br>Thanks,<br clear="all"><br>-- <br>Ed