编写一个伪终端

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <wait.h>
void getstring(char* buf,int size)
{
	fgets(buf,size,stdin);
	int len = strlen(buf);
	if(buf[len-1]==10)
	{
		buf[len-1]=0;
	}
}
int main(int argc, const char *argv[])
{
	while(1)
	{

		int res = fork();
		if(res > 0)
		{
			char* username = getlogin();
			char hostname[128] ={0};
			gethostname(hostname,128);
			char path[128]={0};
			getcwd(path,128);
			printf("\033[1;32;10m%s@%s\033[0m:\033[1;34;10m%s\033[0m$ ",username,hostname,path);
			fflush(stdout);
			wait(0);
		}else if(res == 0)
		{
			char cmd[256] = {0};
			getstring(cmd,256);
			char* arg[32]={0};
			int i = 0;
			char* res = NULL;
			do{
				if(res == NULL)
				{
					res = strtok(cmd," ");
				}else
				{
					res = strtok(NULL," ");
				}
				if(res == NULL){break;}
				arg[i++] = res;
			}while(1);
			if(strcmp(arg[0],"cd")==0)
			{
				if(arg[1][0]==0 || strcmp(arg[1],"~")==0)
				{
					chdir("/home/ubuntu/");		
				}else{
					chdir(arg[1]);
				}
			}else
			{
				execvp(arg[0],arg);
			}
		}else
		{
			perror("fork");
			return 1;
		}
	}
	return 0;
}