13-(1-4)プロセスパイプpopen(-r-w)およびpipeのプログラム使用例について

#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#define BUFSIZE 200
int main()
{
    FILE *read_fp;
    char buffer[BUFSIZE+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),BUFSIZE,read_fp);// ， -1
        /* */
        if(chars_read > 0)
        {
            printf("Output was:-
%s
",buffer);
        }

        pclose(read_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
}
/* ， popen ：
 ，
 
*/

#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#define BUFSIZE 50
int main()
{
    FILE *read_fp;
    char buffer[BUFSIZE+1];/* */
    int chars_read;
    memset(buffer,'\0',sizeof(buffer));
    read_fp=popen("ps ax","r");//   
    /* ， － */
    if(read_fp != NULL)
    {
        while(chars_read > 0)
        {

            // ， -1
            /* */
            chars_read=fread(buffer,sizeof(char),BUFSIZE,read_fp);
            buffer[chars_read-1]='\0';
            printf("Reading %d:-
 %s 
",BUFSIZE,buffer);

        }
        pclose(read_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
    return 0;
}
/* ， popen ：
 ，
 
*/

#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#define BUFSIZE 50
int main()
{
    FILE *read_fp;
    char buffer[BUFSIZE+1];/* */
    int chars_read;
    memset(buffer,'\0',sizeof(buffer));
    read_fp=popen("cat 13-3-*.cpp | wc -l","r");//   
    /* ， － */
    if(read_fp != NULL)
    {
        while(chars_read > 0)
        {

            // ， -1
            /* */
            chars_read=fread(buffer,sizeof(char),BUFSIZE,read_fp);
            buffer[chars_read-1]='\0';
            printf("Reading %d:-
 %s 
",BUFSIZE,buffer);

        }
        pclose(read_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
    return 0;
}
/* ， popen ：
 ，
 
*/

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

#define Buffer 100

int main()
{
    FILE *write_fp;
    char buffer[Buffer + 1];
    // 。
    // ： （strlen）
    sprintf(buffer,"Once upon a time, there was...
");
    //******** ***********///
    //-c： -t c， ASCII 
    write_fp=popen("od -c","w");
    if(write_fp != NULL)
    {
        fwrite(buffer,sizeof(char),strlen(buffer),write_fp);
        pclose(write_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
}

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

int main()
{
    int data_processed;
    int file_pies[2];
    const char some_data[]="123";
    char buffer[BUFSIZ+1];

    memset(buffer,'\0',sizeof(buffer));

    if(pipe(file_pies)==0)
    {
        data_processed=write(file_pies[1],some_data,strlen(some_data));
        printf("Wrote %d bytes
",data_processed);
        data_processed=read(file_pies[0],buffer,BUFSIZ);
        printf("Read %d bytes: %s
",data_processed,buffer);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
}