_more.h

Unix shell是unix的命令解释程序

#include<sys/stat.h>
#include<sys/types.h>
#include<sys/wait.h>
#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<signal.h>
#include<dirent.h>

void _more(char *str)
{
	char c[4];
	long pos[100];
	int i=0,n=0;
	FILE *file=fopen(str,"r+");	
	if(file==NULL)
	{
		printf("can not open file %s\n",str);
		return;
	}
	char buf[80];
	int tag=1;
	

	for(i=0;i<23;i++)
	{
		if(!fgets(buf,80,file))	
		{
			tag=0;
			break;
		}
		else
			fputs(buf,stdout);
	}
	

	pos[n] = ftell(file);
	printf("pos[%d] : %d\n",n,pos[n]);
	n = n+1;
	printf("%s","input \'b\' to quit:");
	while( fgets(c,4,stdin) && tag)
	{
		if(c[0] == 'b' || c[0] == 'B')
		{
			if(n == 1 || n == 2)
			{
				fseek(file,0,SEEK_SET);
				n=0;
			}
			else{
				fseek(file,pos[n-3],SEEK_SET);
				n=n-2;
			}
			
		}
		for(i=0;i<23;i++)
		{
			if(!fgets(buf,80,file))	
		{																																	tag=0;									break;}	else
			{
				fputs(buf,stdout);
			}
			
		}	
		pos[n] = ftell(file);
		printf("pos[%d] : %d\n",n,pos[n]);
		n = n+1;
		c[0] = 0;
		printf("%s","input \'b\' to quit:");
	}
}