《unix环境高级编程》作业题，实现uname

#include "apue.h"
#include <sys/utsname.h>
#include <stdio.h>
 
int
main(int argc,char *argv[])
{
	struct utsname	*name=malloc(1);
	char		*buf=malloc(MAXLINE);
	int		i,j,k=0,flag=0;/*i,j for argv,k for buf,flag for error*/
 
	if(uname(name)==-1)
		err_sys("uname error");
 
	for(i=1;i<argc;i++)
	{
		for(j=0;argv[i][j]!='\0';j++)
		{
			if(argv[i][j]!='-')/*collect the parameters*/
			{
				buf[k]=argv[i][j];
				k++;
			}
		}
	}
	buf[k]='\0';
	
	for(k=0;buf[k]!='\0';k++)
	{
		switch(buf[k])
		{
		case 's':printf("%s ",name->sysname);break;
		case 'n':printf("%s ",name->nodename);break;
		case 'r':printf("%s ",name->release);break;
		case 'v':printf("%s ",name->version);break;
		case 'm':printf("%s ",name->machine);break;
		case 'a':printf("%s %s %s %s %s",name->sysname,name->nodename,
				name->release,name->version,name->machine);
			 break;
		case 'h':printf("***************************************\n");
			 printf("* Parameters            Function      *\n");
			 printf("*     -s           print the sysname  *\n");
			 printf("*     -n           print the nodename *\n");
			 printf("*     -r           print the release  *\n");
			 printf("*     -v           print the version  *\n");
			 printf("*     -m           print the machine  *\n");
			 printf("*     -a           print all of above *\n");
			 printf("***************************************\n");
			 break;
		default: flag=1;
			 printf("%s: extra operand %s\n",argv[0],argv[1]);
			 printf("Try 'uname -h' for more information.\n");
			 break;
		}
		if(flag)break;/*if have extra patameters then break.*/
	}
	printf("\n");
	exit(0);
}