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[英]Does child process get access to pipe if execv() is used after fork()?
[英]Program to pipe output of one process to other process using execv
我正在尝试执行“ sudo conntrack -E -p udp -e NEW”命令,然后将此命令的输出通过管道传送到“ logger”命令,但这不起作用。 有什么明显的问题吗? 因此父级是“ sudo conntrack ....”,它派生了子级“ logger ...”
void main () {
pid_t pid;
int status;
int j=0;
int exe_process;
FILE *prt1;
FILE *prt2;
int fd[2];
char *arg[]={ "sudo", "/usr/sbin/conntrack", "-E", "-p", "udp", "-e", "NEW", NULL };
char *arg1[]={ "/usr/bin/logger", "-t", "log-conntrack", "-p", "daemon.notice", NULL };
if (pipe(fd) < 0)
printf("pipe error\n");
if ((pid = fork()) < 0) /* fork a child process */
{
printf("ERROR: forking child process failed\n");
exit(1);
}
else if (pid > 0) /* for the parent process: */
{
printf("In parent process %d\n",getpid());
close(fd[0]);
if (execvp("/usr/sbin/conntrack", arg) < 0) /* execute the command */
{
printf("ERROR: exec failed\n");
exit(1);
}
prt1=fdopen(fd[1], "ab");
}
else /* for the child: */
{
printf("In parent child %d\n",getpid());
close(fd[1]);
prt2=fdopen(fd[0], "rb");
if (execvp("/usr/bin/logger", arg1) < 0) /* execute the command */
{
printf("ERROR: exec failed\n");
exit(1);
}
}
}
几乎是正确的,但是主要的问题是您需要dup()而不是您尝试使用fdopen
。 dup
将以您想要的方式重定向stdin / stdout。
else if (pid > 0) /* for the parent process: */
{
printf("In parent process %d\n",getpid());
close(fd[0]);
close(1);
dup(fd[1]);
if (execvp("/usr/sbin/conntrack", arg) < 0) /* execute the command */
{
printf("ERROR: exec failed\n");
exit(1);
}
//prt1=fdopen(fd[1], "ab");
}
而在孩子中:
close(0);
dup(fd[0]);
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