管道

#include <stdio.h>

FILE *popen(const char *command,const char *open_mode);

int pclose(FILE *stream_to_close);

 

 

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    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)
    {
        fwrite(buffer,sizeof(char),strlen(buffer),write_fp);
        pclose(write_fp);
    }
    return 0;
}

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    FILE *read_fp;
    char buffer[BUFSIZ+1];
    int chars_read;
    memset(buffer,'\0',sizeof(buffer));

    read_fp=popen("ps -ax","r");

    if(read_fp != NULL)
    {
        chars_read=fread(buffer,sizeof(char),BUFSIZ,read_fp);
        while(chars_read > 0)
        {
            buffer[chars_read-1]='\0';
        printf("Reading:-\n%s\n",buffer);
        chars_read=fread(buffer,sizeof(char),BUFSIZ,read_fp);
        }
    }
    pclose(read_fp);
    return 0;
}

 

读取大量数据：

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    FILE *fread_fp;
    char buffer[BUFSIZ+1];
    int chars_bytes;

    fread_fp=popen("cat popen*.c | wc -l","r");
    if(fread_fp != NULL)
    {
        chars_bytes=fread(buffer,sizeof(char),BUFSIZ,fread_fp);
        while(chars_bytes > 0)
        {
            buffer[chars_bytes-1]='\0';
            printf("\n%s\n",buffer);
            chars_bytes=fread(buffer,sizeof(char),BUFSIZ,fread_fp);
        }
        pclose(fread_fp);
    }
    return 0;
}

 

#include <unistd.h>

int pipe(int file_descripter[2]);

基本使用:

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int main(void)
{
    int data_processed;
    int file_pipes[2];
    const char some_data[]="123";
    char buffer[BUFSIZ+1];
    memset(buffer,'\0',sizeof(buffer));

    if(pipe(file_pipes) == 0)
    {
        data_processed=write(file_pipes[1],some_data,strlen(some_data));
        printf("wrote %d bytes\n",data_processed);
        data_processed=read(file_pipes[0],buffer,BUFSIZ);
        printf("read %d bytes:%s\n",data_processed,buffer);
    }
    return 0;
}

利用fork调用管道:

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    int file_pipes[2];
    int data_processed;
    const char some_data[]="1234";
    char buffer[BUFSIZ+1];
    pid_t fork_result;
    memset(buffer,'\0',sizeof(buffer));

    if(pipe(file_pipes) == 0)
    {
        fork_result=fork();
        if(fork_result==-1)
        {
            fprintf(stderr,"Fork failure");
            return 1;
        }
        if(fork_result==0)
        {
            data_processed=read(file_pipes[0],buffer,BUFSIZ);
            printf("read %d bytes:%s\n",data_processed,buffer);
            return 1;
        }
        else
        {
            data_processed=write(file_pipes[1],some_data,strlen(some_data));
            printf("write %d bytes\n",data_processed);
        }
    }
    return 0;
}