Inter-process Communication:Pipes

最新推荐文章于 2021-06-12 12:24:54 发布

最新推荐文章于 2021-06-12 12:24:54 发布 · 76 阅读

本文介绍了如何使用popen和pclose函数实现进程间的数据传递。通过示例代码展示了如何从外部程序捕获输出以及如何将输出发送到外部程序。这对于理解基本的管道通信机制非常有用。

We use the term pipe to mean connecting a data flow from one process to another.

Perhaps the simplest way of passing data between two programs is with the popen and pclose functions:

#include <stdio.h> FILE *popen(const char *command, const char *open_mode); int pclose(FILE *stream_to_close);

Captureing output from an external program:

#include <unistd.h> #include <stdlib.h> #include <stdio.h> #include <string.h> int main(){ FILE *read_fp; char buffer[BUFSIZ + 1]; int chars_read; memset(buffer, '/0', sizeof(buffer)); read_fp = popen("uname -a", "r"); if (read_fp != NULL){ chars_read = fread(buffer, sizeof(char), BUFSIZ, read_fp); if (chars_read > 0){ printf("Output was:-/n%s/n", buffer); } pclose(read_fp); exit(EXIT_SUCCESS); } exit(EXIT_FAILURE); }

Sending output to an external program:

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> int main(){ FILE *write_fp; char buffer[BUFSIZ + 1]; sprintf(buffer, "Once upon a time, there was.../n"); write_fp = popen("od -c", "w"); if (write_fp != NULL){ //fprintf(write_fp, "Once upon a time.../n"); fwrite(buffer, sizeof(char), strlen(buffer), write_fp); pclose(write_fp); exit(EXIT_SUCCESS); } exit(EXIT_FAILURE); }