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how to logoff in Linux
- Thread starter bardley
- Start date
Basic method is simple:
1) get the pid of the login process for the userid
you want.
2) send the proper signal to the process.
As far as actual code for this...
I wouldn't do it in C, I would roll something in the
shell or awk, it would be simpler.
1) get the pid of the login process for the userid
you want.
2) send the proper signal to the process.
As far as actual code for this...
I wouldn't do it in C, I would roll something in the
shell or awk, it would be simpler.
Brad:
Interesting question. Are you asking
1) if root can kill a specific user from a "C" program. Yes, but what do you do if the user is logged in more than once.
2) if the user can self-terminate from a running "C" program. Yes, but the program needs to get the user's parent process and kill that.
Let me know which one you're interested in (or have I completely missed the boat?)
Regards,
Interesting question. Are you asking
1) if root can kill a specific user from a "C" program. Yes, but what do you do if the user is logged in more than once.
2) if the user can self-terminate from a running "C" program. Yes, but the program needs to get the user's parent process and kill that.
Let me know which one you're interested in (or have I completely missed the boat?)
Regards,
- Thread starter
- #4
Thanks for the ideas. Here's some test code I used. It seems to work ok. (Need to run as root)
Brad Gunsalus
Cymtec Systems, Inc.
bgunsalus@cymtec.com
Code:
#include <stdio.h>
int main (void) {
FILE *fp;
int pid;
char pidstr[10];
char kill_line[50] = "kill ";
if ((fp = popen("ps | grep login", "r")) == NULL) {
printf("didn't work\n");
exit(1);
}
fscanf(fp, "%d", &pid);
sprintf(pidstr, "%d", pid);
strcat(kill_line, pidstr);
printf("%s\n", kill_line);
if (system(kill_line)) {
printf("didn't work\n");
}
return 0;
}Cymtec Systems, Inc.
bgunsalus@cymtec.com
Last word from me on this:
You are using many system calls anyway, it's a waste of time to do this in C IMO.
logout() {
ps -aux | grep "login" | awk -v name="username" ' {
if (NR == 1 && $13 == name) {
system("kill -kill" $2)
}
}'
}
One problem with doing this in C is that the login process is owned by root, so you will have to do some gymnastics to find out who the user is.
You are using many system calls anyway, it's a waste of time to do this in C IMO.
logout() {
ps -aux | grep "login" | awk -v name="username" ' {
if (NR == 1 && $13 == name) {
system("kill -kill" $2)
}
}'
}
One problem with doing this in C is that the login process is owned by root, so you will have to do some gymnastics to find out who the user is.
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