自己动手写shell命令之more

unix下more命令的简单实现：

#include <stdio.h>
#define PAGELEN 24
#define LINELEN 512int do_more(FILE * file);
int see_more(FILE * file);int main(int argc,char * argv[])
{
FILE * fp;
if(argc == 1)
do_more(stdin);
else
{
int argv_index = 1;
while(argc > 1)
{
if((fp = fopen(argv[argv_index],"r")) == NULL)
exit(1);
do_more(fp);
fclose(fp);
argv_index++;
argc--;
}
}
return 0;
}int do_more(FILE * fp)
{
char buffer[LINELEN];
int number_of_lines = 0;
int reply;
FILE * ftty;
ftty = fopen("/dev/tty","r");
if(ftty == NULL)
exit(1);
while(fgets(buffer,LINELEN,fp))
{
if(number_of_lines == PAGELEN)
{
fputs(buffer,stdout);
reply = see_more(ftty);
if(reply == 0)
break;
if(reply == 1)
number_of_lines = 0;
//if(reply == 2)
//number_of_lines--;
}
else
{
number_of_lines++;
fputs(buffer,stdout);
}
}
}int see_more(FILE * fp)
{
char c;
printf("enter your command(q space or enter):");
while((c = getc(stdin)) != EOF)
{
if(c == 'q')//按q退出
return 0;
if(c == ' ')
return 1;//按空格显示下一页
if(c == 'n')
return 2;//按n显示下一行
}
return 3;
}