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(diào)用需要使用到系統(tǒng)保留全局hash數(shù)組%sig,即使 用'$sig{信號名}'截取信號,相當于,在perl程序中出現(xiàn)這個信號時,執(zhí)行我們自己定義某段代碼(子函數(shù))的地址值(定義信號響應函數(shù)),這代碼就是截取這個信息后要執(zhí)行的結(jié)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(zhí)行上面的sub
sleep 15;
print if timeout ,this will not print;
alarm 0; #恢復到默認的狀態(tài)
};
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($@){#出現(xiàn)異常}
else{#無異常，打印文件內(nèi)容
while(){
…
}
close fh;
}
如果eval塊中的程序有語法錯誤、運行時錯誤或者遇到die語句，eval將返回undef。錯誤碼被保存在$@中。