expc55@castle.ed.ac.uk (Andrew Myles) (09/20/90)
Try (assuming file descriptor 1 is still your tty and not a pipe, else
open the tty yourself for any operation e.g. read or write)..
#include <sys/ioctl.h> /* or whatever your machine needs */
int main()
{
ioctl(1,TIOCEXCL); /* no more opens - when I use this I find
that mail demons cannot tell me of new
mail, sysops cannot wall etc... :-) */
/* insert your code here. Any other processes attempting to do
things like open(this tty,O_RDONLY); will fail now even if
this tty is crwxrwxrwx... */
ioctl(1,TIOCNXCL); /* Free device on fildes 1. You didn't
do close(1) did you ? If so, now
you can't re-open it either - so do
NOT do it to other peoples tty unless
they know how to free it.*/
return (0);
}
Hope this works for you. Andrew.subbarao@phoenix.Princeton.EDU (Kartik Subbarao) (09/21/90)
In article <6429@castle.ed.ac.uk> expc55@castle.ed.ac.uk (Andrew Myles) writes: >ioctl(1,TIOCEXCL); /* no more opens - when I use this I find > that mail demons cannot tell me of new > mail, sysops cannot wall etc... :-) */ > This is not the case! "biff", "talk" and "wall" seem to work fine for me even with the tty - exclusive on mode. The reason talk works is because the talk daemon is a root process, and "wall" is a setuid root (or root run) program. As to "mail", it is another thing which works. Root can have his way regardless of what you do. I ran a program like this for quite a while (still do) to stop direct writes on my tty with cat and friends, but still allow talk messages. subbarao@{phoenix or gauguin}.Princeton.EDU -|Internet kartik@silvertone.Princeton.EDU (NeXT mail) -| subbarao@pucc.Princeton.EDU - Bitnet