shell.c

unix下一个实现带参数的简单shell的程序

#include <sys/wait.h>
#include "ourhdr.h"
#include "error.c"
#define MAXARG 10
char *argv[MAXARG];
void sig_int(int signo)
{
	printf("interrupt\n");
	exit(1);
}
void create_argv(char *buf)
{
	int len=strlen(buf);
	int i,j=1;
	for(i=0;i<len;i++)
	{
		if(buf[i]=='\0'||i==(len-1))
			buf[i]=0;
		else if(i>0 && buf[i-1]==0)
		{
			if(j>=MAXARG)
				err_sys("to many arguments");
			argv[j]=buf+i;
			j++;
		}
	}
	if(j>=MAXARG)
		err_sys("too many arguments");
	argv[j]=0;
	argv[0]=buf;
}	
int main(void)
{
	char buf[MAXLINE];
	char *envp[]={"PATH=/bin:/usr/bin:/usr/local/bin:",0};
	pid_t pid;
	int status,j,len;
	if(signal(SIGINT,sig_int)==SIG_ERR)
		err_sys("signal error");
	printf("%%");
	while(fgets(buf,MAXLINE,stdin)!=NULL)
	{
		create_argv(buf);
		if((pid=fork())<0)
			err_sys("fork error");
		else if(pid==0)
		{
			execve(buf,argv,envp);
			err_ret("couldn't execve:%s",buf);
			exit(127);
		}
		if((pid=waitpid(pid,&status,0))<0)
			err_sys("waitpid error");
		printf("%%");
	}
	exit(0);	
}