How can a C/C++ program put itself into background?

Question

What\'s the best way for a running C or C++ program that\'s been launched from the command line to put itself into the background, equivalent to if the user had launched fro

Answer 1

The simplest form of backgrounding is:

if (fork() != 0) exit(0);

In Unix, if you want to background an disassociate from the tty completely, you would do:

1. Close all descriptors which may access a tty (usually 0, 1, and 2).
2. if (fork() != 0) exit(0);
3. setpgroup(0,getpid()); /* Might be necessary to prevent a SIGHUP on shell exit. */
4. signal(SIGHUP,SIG_IGN); /* just in case, same as using nohup to launch program. */
5. fd=open("/dev/tty",O_RDWR);
6. ioctl(fd,TIOCNOTTY,0); /* Disassociates from the terminal */
7. close(fd);
8. if (fork() != 0) exit(0); /* just for good measure */

That should fully daemonize your program.