perl fork()exec()，子进程变得疯狂 [英] perl fork() exec() , child process gone wild
问题描述
我正在使用Linux，而.sh在tcsh中.
I am using Linux and .sh is in tcsh.
我做了一个非常基本的叉子和
I have made a very basic fork and exec, but I need help in implementing safeties to it.
基本上，我的perl脚本在子进程中调用.sh脚本.但是当我Ctrl+c杀死父母时，孩子会忽略该信号.
Basically my perl script calls a .sh script in a child process. But when I do Ctrl+c to kill the parent, the signal gets ignored by the child.
1)我如何也捕获子进程的SIGINT?
1) How do I capture the SIGINT for the child process as well?
2)运行.sh脚本的子进程仍然STDOUT到xterm的屏幕.我该如何删除?我当时正在考虑在后台运行脚本
2) The child process that runs the .sh script still STDOUT to the screen of the xterm. How can I remove this? I was thinking of doing running the script in the background
exec("shell.sh args &");
但是还没有进行测试，因为我需要弄清楚如何防止孩子先变得疯狂.
But haven't tested as I need to figure out how to keep the child from going wild first.
3)父进程(perl脚本)不等待子进程(.sh脚本).所以我读了很多关于孩子成为僵尸的信息???脚本完成后会发生吗?而我将如何停止呢?
3) The parent process(perl script) doesn't wait on the child(.sh script). So I've read a lot about the child becoming a zombie??? Will it happen after the script is done? And how would I stop it?
$pid = fork();
if($pid < 0){
print "Failed to fork process... Exiting";
exit(-1);
}
elsif ($pid ==0) {
#child process
exec("shell.sh args");
exit(1);
}
else { #execute rest of parent}
推荐答案
但是当我执行ctrl + c杀死父级时，子级会忽略该信号.
But when I do ctrl+c to kill the parent, the signal gets ignored by the child.
信号被发送给父母和孩子两个.
The signal is sent to two both the parent and the child.
$ perl -E'
if (my $pid = fork()) {
local $SIG{INT} = sub { say "Parent got SIGINT" };
sleep;
waitpid($pid, 0);
} else {
local $SIG{INT} = sub { say "Child got SIGINT" };
sleep;
}
'
^CParent got SIGINT
Child got SIGINT
如果那个孩子忽略了它，那是因为它开始了一个新的会话，或者是因为它明确地忽略了它.
If that child ignores it, it's because it started a new session or because it explicitly ignores it.
运行.sh脚本的子进程仍然STDOUT到xterm的屏幕.我该如何删除呢?
The child procces that runs the .sh script still STDOUT to the screen of the xterm. How can I remove this?
在调用exec之前在孩子中执行以下操作:
Do the following in the child before calling exec:
open(STDOUT, '>', '/dev/null');
open(STDERR, '>', '/dev/null');
实际上，我会使用 open3 进行一些错误检查. /p>
Actually, I would use open3 to get some error checking.
open(local *CHILD_STDIN, '<', '/dev/null') or die $!;
open(local *CHILD_STDOUT, '>', '/dev/null') or die $!;
my $pid = open3(
'<&CHILD_STDIN',
'>&CHILD_STDOUT',
'>&CHILD_STDOUT',
'shell.sh', 'args',
);
父进程(perl脚本)不等待子进程(.sh脚本).所以我读了很多关于孩子成为僵尸的故事?
The parent process(perl script) doesn't wait on the child(.sh script). So I've read alot about the child becoming a zombie???
孩子在父母退出时或在父母退出后退出时会自动获得收成.
Children are automatically reaped when the parent exits, or if they exit after the parent exits.
$ perl -e'
for (1..3) {
exec(perl => (-e => 1)) if !fork;
}
sleep 1;
system("ps");
' ; ps
PID TTY TIME CMD
26683 pts/13 00:00:00 bash
26775 pts/13 00:00:00 perl
26776 pts/13 00:00:00 perl <defunct> <-- zombie
26777 pts/13 00:00:00 perl <defunct> <-- zombie
26778 pts/13 00:00:00 perl <defunct> <-- zombie
26779 pts/13 00:00:00 ps
PID TTY TIME CMD
26683 pts/13 00:00:00 bash
26780 pts/13 00:00:00 ps
<-- all gone
如果父母先于孩子退出，那就没问题了.
If the parent exits before the children do, there's no problem.
如果父母在孩子们离开后不久就退出了，那就没问题了.
If the parent exits shortly after the children do, there's no problem.
如果父母在孩子离开后很长时间退出了，您将希望获得他们的收获.您可以使用wait或waitpid(可能来自SIGCHLD处理程序)来执行此操作，也可以使用$SIG{CHLD} = 'IGNORE';使它们自动收割.参见 perlipc .
If the parent exits a long time after the children do, you'll want to reap them. You could do that using wait or waitpid (possibly from a SIGCHLD handler), or you could cause them to be automatically reaped using $SIG{CHLD} = 'IGNORE';. See perlipc.
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