ctrl+c不能终止进程（busybox提示can't access tty.job control
在最近的一段时间中，发现在busybox下调试时，shell终端用ctrl+c不能终止掉正在运行的进程。参考了网上的一些网友的blog的解决方法连同自己的理解，这边把解决方法告诉大家。 Ctrl+C终止进程的流程是这样的： Ctrl + C首先通过 /dev/ttyS0 (/dev/console)的driver，这个serial driver直接把这个控制字符送到n_tty的driver，n_tty负责search任何的控制字符。 当 ctrl+C 按下， n_tty.c: n_tty_receive_break() –> isig(SIGINT,tty) –> kill_pg(SIGINT, tty->pgrp) signal.c: kill_pg() calls signal(SIGINT,task) 来中断每个具备group number 为 tty->pgrp的task.值得一提的是，只要process具备相同的group id，不管是backgroud还是foreground，都会被kill掉 从上面的流程我们能够看到，ctrl+C是传送到/dev/ttyS0中的驱动中的。在我原来的文档系统中，建立了节点console作为系统控制台。但是没有ttyS0节点。这样系统运行起来后，shell的交互是通过console这个控制台的。但是在busybox的手册中有这样的一段话： Why do I keep getting "sh: can't access tty; job control turned off" errors? Why doesn't Control-C work within my shell? This isn't really a uClibc question, but I'll answer it here anyways. Job control will be turned off since your shell can not obtain a controlling terminal. This typically happens when you run your shell on /dev/console. The kernel will not provide a controlling terminal on the /dev/console device. Your should run your shell on a normal tty such as tty1 or ttyS0 and everything will work perfectly. If you REALLY want your shell to run on /dev/console, then you can hack your kernel (if you are into that sortof thing) by changing drivers/char/tty_io.c to change the lines where it sets "noctty = 1;" to instead set it to "0". I recommend you instead run your shell on a real console... 显然，busybox建议我们shell最好运行在实际的控制台上，例如tty或是ttyS0中。
# ping 192.168.2.245 PING 192.168.2.245 (192.168.2.245): 56 data bytes 64 bytes from 192.168.2.245: icmp_seq=0 ttl=64 time=2.1 ms 64 bytes from 192.168.2.245: icmp_seq=1 ttl=64 time=0.6 ms 64 bytes from 192.168.2.245: icmp_seq=2 ttl=64 time=0.4 ms 64 bytes from 192.168.2.245: icmp_seq=3 ttl=64 time=0.4 ms
--- 192.168.2.245 ping statistics --- 4 packets transmitted, 4 packets received, 0% packet loss round-trip min/avg/max = 0.4/0.8/2.1 ms #
