Linux中more命令的实现

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define PAGELEN 24

#define LINELEN 512



void do_more(FILE *);

int see_more(FILE *);



int main(int argc, char *argv[])

{

    FILE *fp;

    if (argc == 1)

        do_more(stdin);

    else

    {   

        while (--argc)

        {   

            if ((fp = fopen(*++argv, "r")) != NULL)

            {   

                do_more(fp);

                fclose(fp);

            }   

            else

                exit(1);

        }   

    }   

    return 0;

}



void do_more(FILE *fp)

{

    char line[LINELEN];

    int num_of_lines = 0;

    int reply;

    FILE *fp_tty;

    fp_tty = fopen("/dev/tty", "r");

    if(fp_tty == NULL)

        exit(1);

    while (fgets(line, LINELEN, fp))

    {

        if (num_of_lines == PAGELEN)

        {

            reply = see_more(fp_tty);

            if(reply == 0)

                break;

            num_of_lines -= reply;

        }

        if (fputs(line, stdout) == EOF)

            exit(1);

        num_of_lines++;

    }

}



int see_more(FILE *cmd)

{

    int c;

    printf("\033[7m more? \033[m");

    while ((c = getc(cmd)) != EOF)

    {

        if (c == 'q')

            return 0;

        if (c == ' ')

            return PAGELEN;

        if (c == '\n')

            return 1;

    }

    return 0;

}

还有许多缺陷