Unix 下常见的处理信号

No    Name         Default Action       Description

 1     SIGHUP       terminate process    terminal line hangup

 2     SIGINT       terminate process    interrupt program

 3     SIGQUIT      create core image    quit program

 4     SIGILL       create core image    illegal instruction

 5     SIGTRAP      create core image    trace trap

 6     SIGABRT      create core image    abort program (formerly SIGIOT)

 7     SIGEMT       create core image    emulate instruction executed

 8     SIGFPE       create core image    floating-point exception

 9     SIGKILL      terminate process    kill program

 10    SIGBUS       create core image    bus error

 11    SIGSEGV      create core image    segmentation violation

 12    SIGSYS       create core image    non-existent system call invoked

 13    SIGPIPE      terminate process    write on a pipe with no reader

 14    SIGALRM      terminate process    real-time timer expired

 15    SIGTERM      terminate process    software termination signal

 16    SIGURG       discard signal       urgent condition present on socket

 17    SIGSTOP      stop process         stop (cannot be caught or ignored)

 18    SIGTSTP      stop process         stop signal generated from keyboard

 19    SIGCONT      discard signal       continue after stop

 20    SIGCHLD      discard signal       child status has changed

 21    SIGTTIN      stop process         background read attempted from control terminal

 22    SIGTTOU      stop process         background write attempted to control terminal

 23    SIGIO        discard signal       I/O is possible on a descriptor (see fcntl(2))

 24    SIGXCPU      terminate process    cpu time limit exceeded (see setrlimit(2))

 25    SIGXFSZ      terminate process    file size limit exceeded (see setrlimit(2))

 26    SIGVTALRM    terminate process    virtual time alarm (see setitimer(2))

 27    SIGPROF      terminate process    profiling timer alarm (see setitimer(2))

 28    SIGWINCH     discard signal       Window size change

 29    SIGINFO      discard signal       status request from keyboard

 30    SIGUSR1      terminate process    User defined signal 1

 31    SIGUSR2      terminate process    User defined signal 2

perl的信号处理原理

Perl 提供了%SIG 这个特殊的默认HASH.调用需要使用到系统保留全局HASH数组%SIG,即使 用'$SIG{信号名}'截取信号,相当于,在perl程序中出现这个信号时,执行我们自己定义某段代码(子函数)的地址值(定义信号响应函数),这代码就是截取这个信息后要执行的结果了.

举个SIGALRM例子，也就是超时处理：

my $timeout = 10 ;

    eval {

        local $SIG{ALRM} = sub { die "alarmn" }; # n required

        alarm $timeout; #如果到了$timeout时间就会去执行上面的sub

        sleep 15;

        print " if timeout ,this will not print";

        alarm 0; #恢复到默认的状态

    };

    if ($@) {

        die  unless $@ eq "alarmn";   #可能捕获的不是超时，是其他错误，就die吧

        print "timeout n" ;

    }

    else {

        print "not timeout";

    }

这里要说一下perl的错误捕获机制

eval {

open(FH,”domains.txt”) or die “Can't open files,$!”;

};

捕获异常

if($@){#出现异常}

else{#无异常，打印文件内容

while(){

…

}

close FH;

}

如果eval块中的程序有语法错误、运行时错误或者遇到die语句，eval将返回undef。错误码被保存在$@中。

perl AnyEvent简单介绍和入门知识
什么是面向事件的编程(事件驱动的编程):编程中所有的程序是由事件决定?可以是由用户操作(键盘,鼠标)，也可以是由其他程序和流的到达或者操作系统

Perl AnyEvent中的watcher实例
这几天看了下perl的事件编程框架AnyEvent,重点参考了一下几篇文章：http://search.cpan.org/~mlehmann/AnyEvent-7.05/lib/AnyEvent.pmhttp://search.cpan.org/~mlehmann/AnyEvent-7.05/lib

perl 采集入库脚本分享
#!/usr/bin/perl-wuseDBI;usePOSIXqw(strftime);my$dbh=DBI-connect(DBI:mysql:shencan:111.1.32.153:3306″,shencan,shencan);#my$sql=select*fromshencan.LVS;#my$sth=$dbh-prepare($sql);#$sth-execute();my$HOS