C-将STDERR从服务重定向到Syslog

Question

我必须运行一个perl脚本作为服务（即守护程序）。我在下面找到了C程序，一般来说，它可以正常工作。但是，如果perl脚本死亡，但我不会收到任何错误消息。我如何从perl获得错误？

终端（即Stderr）不可用，我认为最好的想法是在syslog中获取错误消息。

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>
#include <signal.h>
#include <syslog.h>

int main( int argc, char *argv[] ) {    
    pid_t pid, sid;    
    if( argc < 1 ) {
        printf("At least one argument expected.n");
        return EXIT_FAILURE;
    }
    char arg[1000];
    strcpy(arg, argv[1]);
    int i = 2;
    for(i = 2; i < argc; i++) {
        strcat(arg, " ");
        strcat(arg, argv[i]);       
    }
    /* Fork off the parent process */
    pid = fork();
    if (pid < 0) {
        exit(EXIT_FAILURE);
    }
    /* If we got a good PID, then we can exit the parent process. */
    if (pid > 0) {
        exit(EXIT_SUCCESS);
    }
    /* Open a connection to the syslog server */
    openlog ("mediationd", LOG_PID, LOG_DAEMON); 
    syslog(LOG_NOTICE, "Successfully started daemonn"); 
    /* Try to create our own process group */
    sid = setsid();
    if (sid < 0) {
        syslog(LOG_ERR, "Could not create process groupn");
        closelog();
        exit(EXIT_FAILURE);
    }
    /* Catch, ignore and handle signals */
    signal(SIGCHLD, SIG_IGN);
    signal(SIGHUP, SIG_IGN);
    /* Fork off for the second time*/
    pid = fork();
    /* An error occurred */
    if (pid < 0) {
        syslog(LOG_ERR, "Could not fork second timen");
        closelog();
        exit(EXIT_FAILURE);
    }
    /* Success: Let the parent terminate */
    if (pid > 0) {
        exit(EXIT_SUCCESS);
    }
    /* Change the file mode mask */
    umask(0);       
    /* Change the current working directory */
    if ((chdir("/")) < 0) {
        syslog(LOG_ERR, "Could not change working directory to /n");
        exit(EXIT_FAILURE);
    }
    /* Close the standard file descriptors */
    close(STDIN_FILENO);
    close(STDOUT_FILENO);
    close(STDERR_FILENO);
    /* Starting the perl script which does the job. 
    * Note, this perl scripts runs forever till it is terminated by 'kill' command */
    system(arg);
    /* Terminate the daemon */
    syslog (LOG_NOTICE, "Daemon terminated.");
    closelog();
    return EXIT_SUCCESS;
}

我用简单的复制/粘贴写了这个小程序，因为我对C.

update

我更新了我的代码，如下所示。它似乎运行良好，但是我会错过任何东西还是应该添加其他东西？

/* Close the standard file descriptors */
close(STDIN_FILENO);
close(STDOUT_FILENO);
/* Redirect STDERR to syslog, i.e. logger */
FILE *fl;
fl = popen("logger --id --priority user.error", "w");
if (fl == NULL) {
    syslog(LOG_ERR, "Could not open 'looger'n");
    exit(EXIT_FAILURE);
}
int nf = fileno(fl);
dup2(nf, STDERR_FILENO);
/* Starting the perl script which does the job. 
* Note, this perl scripts runs forever till it is terminated by 'kill' command */
system(arg);
close(STDERR_FILENO);
/* Terminate the daemon */
syslog (LOG_NOTICE, "Daemon terminatedn");
closelog();
return EXIT_SUCCESS; 

Answer 1

如果您想在本机Perl中进行，这对我有用：

use IO::Handle;
open(SYSLOG, "| /usr/bin/logger -t hello") or die( "syslog problem $!" );
*STDERR = *SYSLOG;
autoflush STDERR 1;

如果Perl用die()崩溃或类似，您将看到日志消息。