NAME       popen, pclose - pipe stream to or from a processSYNOPSIS       #include <stdio.h>       FILE *popen(const char *command, const char *type);       int pclose(FILE *stream);DESCRIPTION       The popen() function opens a process by creating a pipe,  forking,  and       invoking  the shell.  Since a pipe is by definition unidirectional, the       type argument may specify  only  reading  or  writing,  not  both;  the       resulting stream is correspondingly read-only or write-only.       The  command argument is a pointer to a null-terminated string contain-       ing a shell command line.  This command is passed to /bin/sh using  the       -c  flag;  interpretation, if any, is performed by the shell. RETURN VALUE       The popen() function returns NULL if the fork(2) or pipe(2) calls fail,       or if it cannot allocate memory.       The pclose() function returns -1 if wait4(2) returns an error, or  some       other error is detected.

/*************************************************************************    > File Name: popen.c    > Author: KrisChou    > Mail:zhoujx0219@163.com     > Created Time: Fri 22 Aug 2014 11:07:26 AM CST ************************************************************************/#include <stdio.h>#include <stdlib.h>#include <string.h>int main(int argc, char *argv[]){    char buf[1024];    FILE *fp;        while(memset(buf,0,1024),fgets(buf,1024,stdin) != NULL)    {        fp = popen(argv[1],"w");        fputs(buf,fp);        pclose(fp);    }    return 0;}

/*************************************************************************    > File Name: reverse.c    > Author: KrisChou    > Mail:zhoujx0219@163.com     > Created Time: Sat 23 Aug 2014 11:21:27 AM CST ************************************************************************/#include <stdio.h>#include <stdlib.h>#include <string.h>int main(int argc, char *argv[]){    char word[256]; //从标准输入读取字符串    char buf[256][256],index = 0; //保存从标准输入读取的字符串    while(memset(word,0,256), scanf("%s",word) != EOF )    {        strcpy(buf[index++],word);    }    index--;    while(index >=0 )    {        printf("%s ",buf[index]);        index--;    }    printf("\n");    return 0;}

[purple@localhost popen]$ gcc popen.c -o main[purple@localhost popen]$ gcc reverse.c -o reverse[purple@localhost popen]$ ./main ./reversehow are youyou are howbaby u r beautifulbeautiful r u baby[purple@localhost popen]$