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Unix 下常見的處理信號

代碼如下:

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的信號處理原理

Perl 提供了%SIG 這個特殊的默認HASH.調用需要使用到系統保留全局HASH數組%SIG,即使 用'$SIG{信號名}'截取信號,相當于,在perl程序中出現這個信號時,執行我們自己定義某段代碼(子函數)的地址值(定義信號響應函數),這代碼就是截取這個信息后要執行的結果了.

舉個SIGALRM例子，也就是超時處理：

代碼如下:

my $timeout = 10 ;

eval {

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

alarm $timeout; #如果到了$timeout時間就會去執行上面的sub

sleep 15;

print " if timeout ,this will not print";

alarm 0; #恢復到默認的狀態

};

if ($@) {

die unless $@ eq "alarm\n"; #可能捕獲的不是超時，是其他錯誤，就die吧

print "timeout \n" ;

}

else {

print "not timeout";

}

這里要說一下perl的錯誤捕獲機制

代碼如下:

eval {

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

};

捕獲異常

代碼如下:

if($@){#出現異常}

else{#無異常，打印文件內容

while(){

…

}

close FH;

}

如果eval塊中的程序有語法錯誤、運行時錯誤或者遇到die語句，eval將返回undef。錯誤碼被保存在$@中。

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