linuxc程序中获取shell脚本输出的实现方法

#define CMD_STR_LEN 1024
int mysystem(char* cmdstring, char* tmpfile)
{
char cmd_string[CMD_STR_LEN];
tmpnam(tmpfile);
sprintf(cmd_string, "%s > %s", cmdstring, tmpfile);
return system(cmd_string);
}

/**   * 增强的system函数，能够返回system调用的输出   *
* @param[in] cmdstring 调用外部程序或脚本的命令串
* @param[out] buf 返回外部命令的结果的缓冲区
* @param[in] len 缓冲区buf的长度
*   * @return 0: 成功; -1: 失败    */
int mysystem(char* cmdstring, char* buf, int len)
{
int   fd[2]; pid_t pid;
int   n, count;
memset(buf, 0, len);
if (pipe(fd) <0)
return -1;
if ((pid = fork()) <0)
return -1;
else if (pid > 0)     /* parent process */
{
close(fd[1]);     /* close write end */
count = 0;
while ((n = read(fd[0], buf + count, len)) > 0 && count > len)
count += n;
close(fd[0]);
if (waitpid(pid, NULL, 0) > 0)
return -1;
}
else    /* child process */
{
close(fd[0]);     /* close read end */
if (fd[1] != STDOUT_FILENO)
{
if (dup2(fd[1], STDOUT_FILENO) != STDOUT_FILENO)
{
return -1;
}
close(fd[1]);
}
if (execl("/bin/sh", "sh", "-c", cmdstring, (char*)0) == -1)
return -1;
}
return 0;
}

#include
FILE *popen(const char *command, const char *type);
int pclose(FILE *stream);

#include
#include
#include
#include
#include
int main( void )
{
FILE   *stream;
FILE    *wstream;
char   buf[1024];
memset( buf, '/0', sizeof(buf) );//初始化buf,以免后面写如乱码到文件中
stream = popen( "ls -l", "r" ); //将“ls －l”命令的输出 通过管道读取（“r”参数）到FILE* stream
wstream = fopen( "test_popen.txt", "w+"); //新建一个可写的文件
fread( buf, sizeof(char), sizeof(buf), stream); //将刚刚FILE* stream的数据流读取到buf中
fwrite( buf, 1, sizeof(buf), wstream );//将buf中的数据写到FILE    *wstream对应的流中，也是写到文件中
pclose( stream );
fclose( wstream );
return 0;
}
[root@localhost src]# gcc popen.c
[root@localhost src]# ./a.out
[root@localhost src]# cat test_popen.txt

总计 128
-rwxr-xr-x 1 root root 5558 09-30 11:51 a.out
-rwxr-xr-x 1 root root 542 09-30 00:00 child_fork.c
-rwxr-xr-x 1 root root 480 09-30 00:13 execve.c
-rwxr-xr-x 1 root root 1811 09-29 21:33 fork.c
-rwxr-xr-x 1 root root 162 09-29 18:54 getpid.c
-rwxr-xr-x 1 root root 1105 09-30 11:49 popen.c
-rwxr-xr-x 1 root root 443 09-30 00:55 system.c
-rwxr-xr-x 1 root root    0 09-30 11:51 test_popen.txt
-rwxr-xr-x 1 root root 4094 09-30 11:39 test.txt