mvandoornik
07-11-2005, 11:38 AM
Greetings!
As I'm using Kanotix (which doesn't seem to have such an extensive forum) and it's based on Knoppix, I figure I'll post this question here.
For a program which will use the parallel port for digital I/O, I'm trying to get access to the port WITHOUT being root (no sudo, either). For this, I've compiled a simple program in C, but it keeps complaining it has no permissions to access the port (/dev/parport0). Port permissions are as follows:
crw-rw-rw- 1 root root 99, 0 Feb 9 19:40 /dev/parport0
The program has been compiled using gcc -O1 -o test test.c, after which I've issued (as root):
chown root:users test
chmod u+s test
I figured it should work now, but it doesn't. Keeps complaining about permissions.
Furthermore I've tried creating a file foo.txt and done chmod 600 foo.txt. Then made an executable script bar.sh, which just cat's foo.txt. Then:
chown root:users bar.sh
chmod u+s bar.sh
Executing bar.sh also gives permission errors. So in other words: what gives? I'm stumped, but I've probably misunderstood how suid root works. Any help would be greatly appreciated.
Thanks in advance,
Marc.
As I'm using Kanotix (which doesn't seem to have such an extensive forum) and it's based on Knoppix, I figure I'll post this question here.
For a program which will use the parallel port for digital I/O, I'm trying to get access to the port WITHOUT being root (no sudo, either). For this, I've compiled a simple program in C, but it keeps complaining it has no permissions to access the port (/dev/parport0). Port permissions are as follows:
crw-rw-rw- 1 root root 99, 0 Feb 9 19:40 /dev/parport0
The program has been compiled using gcc -O1 -o test test.c, after which I've issued (as root):
chown root:users test
chmod u+s test
I figured it should work now, but it doesn't. Keeps complaining about permissions.
Furthermore I've tried creating a file foo.txt and done chmod 600 foo.txt. Then made an executable script bar.sh, which just cat's foo.txt. Then:
chown root:users bar.sh
chmod u+s bar.sh
Executing bar.sh also gives permission errors. So in other words: what gives? I'm stumped, but I've probably misunderstood how suid root works. Any help would be greatly appreciated.
Thanks in advance,
Marc.