标准输出重定向加管道，获取system命令执行结果

#include <stdlib.h>

#include <string.h>

#include <stdio.h>

#include <fcntl.h>

#include <unistd.h>

static int getResultFromSystemCall(const char* pCmd, char* pResult, int size)

{

int fd[2];

if(pipe(fd)) {

printf("pipe error!\n");

return -1;

}

//prevent content in stdout affect result

fflush(stdout);

//hide stdout

int bak_fd = dup(STDOUT_FILENO);

int new_fd = dup2(fd[1], STDOUT_FILENO);

//the output of `pCmd` is write into fd[1]

system(pCmd);

read(fd[0], pResult, size-1);

pResult[strlen(pResult)-1] = 0;

//resume stdout

dup2(bak_fd, new_fd);

return 0;

}

int main(void)

{

char* filePath = "./test.conf";

char* key = "aaa";

char res[100] = {0};

char cmd[100] = {0};

sprintf(cmd, "cat %s | grep -m 1 -E \"^%s\" | cut -d= -f2 | sed 's/[[:space:]]*//g'", filePath, key);

getResultFromSystemCall(cmd, res, sizeof(res)/sizeof(res[0]));

//getResultFromSystemCall("export aaa=1234 && echo ${aaa#=}", res, sizeof(res)/sizeof(res[0]));

printf("result is [%s]\n", res);

return 0;

}

转自：http://www.oschina.net/code/snippet_616273_14056#viewSource

dup和dup2使用

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