fork创建守护进程失败

-2

我有一个C程序，它被调用了可变参数。该程序使用参数形成命令，然后分叉创建子进程。但是，当程序的参数数量较多时，我发现fork()命令失败。fork创建守护进程失败

任何线索为什么会发生这种情况？

int main(int argc, char *argv[]) 
{ 
    FILE *logfile; 
    int other=0; 
    int i, pid; 
    char *conn="conntrack -E"; 
    char *logger="logger -t log-conntrack -p daemon.notice"; 
    char *fother="grep -vE 'tcp|udp|icmp'"; 
    char cmd[1024]; 
    int length = 0; 
    char * temp_cmd = cmd; 

    for (i=1; i<argc; i++) { 
    printf("for loop\n"); 
     switch(argv[i][1]) { 
     case 'p': if (i+1 < argc && argv[i+1][0] != '-') { 
          if (strncmp(argv[i+1], "other", 
             strlen(argv[i+1])) == 0) { 
            other=1; 
            snprintf(cmd, sizeof (cmd), "%s", conn); 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } else if ((strncmp(argv[i+1], "tcp", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "udp", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "icmp", 
              strlen(argv[i+1])) == 0)) { 
            snprintf(cmd, sizeof (cmd), "%s%s%s", conn, " -p ", argv[i+1]); 
            other=0; 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } 
        } 
        break; 
case 'e': 
        if (i+1 < argc && argv[i+1][0] != '-') { 
          if ((strncmp(argv[i+1], "NEW", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "UPDATES", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "DESTROY", 
              strlen(argv[i+1])) == 0)) { 
            if (other == 1) { 
             snprintf(temp_cmd, sizeof (cmd) - length, "%s%s%s%s%s%s%s", " -e ", argv[i+1], " -o id", " | ", fother, " | ", logger); 
             cmds[pcounter] = malloc(strlen+1); 
             strcpy(cmds[pcounter],cmd); 
             pcounter++; 
            } else if ((strncmp(argv[i-1], "tcp",strlen(argv[i-1]))==0) && 
               (strncmp(argv[i+1], "UPDATES",strlen(argv[i+1])) == 0)){ 
             snprintf(temp_cmd, sizeof (cmd) - length, "%s%s", " -e ", argv[i+1]); 
            } else { 
             snprintf(temp_cmd, sizeof (cmd) - length, "%s%s%s%s%s", " -e ", argv[i+1], " -o id", " | ", logger); 
             cmds[pcounter] = malloc(strlen+1); 
             strcpy(cmds[pcounter],cmd); 
             pcounter++; 
            } 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } 
        } 
        break; 
     case 's': if (i+1 < argc && argv[i+1][0] != '-') { 
          if ((strncmp(argv[i+1], "SYN_RECV", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "ESTABLISHED", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "FIN_WAIT", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "CLOSE_WAIT", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "LAST_ACK", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "TIME_WAIT", 
              strlen(argv[i+1])) == 0)) { 
            snprintf(temp_cmd, sizeof (cmd) - length, "%s%s%s%s%s", " --state ", argv[i+1], " -o id", " | ", logger); 
            cmds[pcounter] = malloc(strlen+1); 
            strcpy(cmds[pcounter],cmd); 
            pcounter++; 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } 
        } 
        break; 
    } 
    } 
    daemonize(); 
}

的ulimit -a输出 -

ulimit -a 
core file size   (blocks, -c) 0 
data seg size   (kbytes, -d) unlimited 
scheduling priority    (-e) 0 
file size    (blocks, -f) unlimited 
pending signals     (-i) 16382 
max locked memory  (kbytes, -l) 64 
max memory size   (kbytes, -m) unlimited 
open files      (-n) 1024 
pipe size   (512 bytes, -p) 8 
POSIX message queues  (bytes, -q) 819200 
real-time priority    (-r) 0 
stack size    (kbytes, -s) 8192 
cpu time    (seconds, -t) unlimited 
max user processes    (-u) unlimited 
virtual memory   (kbytes, -v) unlimited 
file locks      (-x) unlimited 


free -m 
      total  used  free  shared buffers  cached 
Mem:   502  123  379   0   19   72 
-/+ buffers/cache:   31  471 
Swap:   0   0   0

来源

2011-12-04 user1060517

获得这些问题的答案的最佳方式是显示一些代码，最好是可运行的示例。 – cnicutar

请发布您的代码。 100次中有99次是这样的，这些问题是由于实现错误，而不是API的功能中的错误。 – Polynomial

最明显的将是你正在达到一定的资源限制。但是由于您（a）没有发布代码，（b）**甚至没有提供失败的fork后面的'errno' /'perror'，很难提供很多帮助。 – derobert

这里的问题是分支没有足够的内存来分配给子进程。我增加了运行该程序的虚拟机的内存，并且工作。

来源

2011-12-05 18:28:19 user1060517

fork创建守护进程失败

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