无法使用Ctrl + c终止Shell命令 [英] Cannot terminate a shell command with Ctrl+c
问题描述
有人可以告诉我为什么 Ctrl + c 不能正确终止bash语句吗?
Would someone please tell me why below bash statement cannot be terminated by Ctrl+c properly?
$( { ( tail -fn0 /tmp/a.txt & )| while read line; do echo $line; done } 3>&1 )
我运行此语句，然后启动两个bash进程和一个tail进程(从ps auxf获取)，然后输入 Ctrl + c ，它不会退出到在bash提示符下，此时，我看到两个bash进程停止了，而tail仍在运行，然后在/tmp/a.txt中输入了一些内容，然后我们进入了bash提示符.
I run this statement, then two bash processes and one tail process are launched(got from ps auxf), then input Ctrl+c, and it won't quit to the bash prompt, at this moment, I see the two bash processes stopped, while the tail is still running, then I input something into /tmp/a.txt, then we could get into bash prompt.
我想要的是，输入 Ctrl + c ，然后直接退出bash提示符而没有任何相关过程.
What I want is, input Ctrl+c, then just quit into bash prompt without any relevant process left.
有人解释此语句的确切过程会更有意义，例如用管道导致bash分支，将某些内容重定向到某个地方等.
It will be more appreciative that someone explains the exact process of this statement, like a pipe causes the bash fork, something redirect to somewhere, etc.
2014年10月9日更新:
在此提供一些更新，以防对您有用. 我采用的解决方案与以下两个因素相似:
Here provide some update in case it's useful to you. My adopt solution is alike with 2 factors:
-
使用tmp pid文件
use a tmp pid file
( tail -Fn0 ${monitor_file} & echo "$!" >${tail_pid} ) | \
while IFS= read -r line; do
xxxx
done
使用陷阱，例如:trap "rm ${tail_pid} 2>/dev/null; kill 0 2>/dev/null; exit;" INT TERM杀死相关进程并删除剩余文件.
use trap like: trap "rm ${tail_pid} 2>/dev/null; kill 0 2>/dev/null; exit;" INT TERM to kill relevant processes and remove remain files.
请注意，此kill 0 2是特定于bash的，0表示当前进程组中的所有进程.
此解决方案使用了tmp pid文件，而我仍然希望其他没有tmp pid文件的解决方案.
Please note, this kill 0 2 is bash specific, and 0 means all processes in the current process group.
This solution used a tmp pid file, while I still expect other solution without tmp pid file.
推荐答案
它可以捕获INT信号(由Ctrl-C发送)以杀死tail进程.
It works to trap the INT signal (sent by Ctrl-C) to kill the tail process.
$( r=$RANDOM; trap '{ kill $(cat /tmp/pid$r.pid);rm /tmp/pid$r.pid;exit; }' SIGINT EXIT; { ( tail -fn0 /tmp/a.txt & echo $! > /tmp/pid$r.pid )| while read line; do echo $line; done } 3>&1 )
(我在PID文件名上使用了随机值，至少在大多数情况下允许多个实例运行)
(I use a random value on the PID file name to at least mostly allow multiple instances to run)
这篇关于无法使用Ctrl + c终止Shell命令的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
