代码

`#include <stdio.h>

include <stdlib.h>

include <string.h>

include <sys/types.h>

include <sys/wait.h>

include <unistd.h>

include <signal.h>

define MAXARGS 20

define ARGLEN 100

char *makestring( char *buf )
{
char *cp;

buf[strlen(buf)-1] = '\0';		
cp = malloc( strlen(buf)+1 );		
if ( cp == NULL ){			
	fprintf(stderr,"no memory\n");
	exit(1);
}
strcpy(cp, buf);		
return cp;			

}

void execute( char *arglist[] )
{
int pid,exitstatus;

pid = fork();					
switch( pid ){
	case -1:	
		perror("fork failed");
		exit(1);
	case 0:
		execvp(arglist[0], arglist);		
		perror("execvp failed");
		exit(1);
	default:
		while( wait(&exitstatus) != pid )
			;
		printf("child exited with status %d,%d\n",
				exitstatus>>8, exitstatus&0377);
}

}

int main()
{
char *arglist[MAXARGS+1];
int numargs;
char argbuf[ARGLEN];

numargs = 0;
while ( numargs < MAXARGS )
{					
	printf("Arg[%d]? ", numargs);
	if ( fgets(argbuf, ARGLEN, stdin) && *argbuf != '\n' )
		arglist[numargs++] = makestring(argbuf);
	else
	{
		if ( numargs > 0 ){		
			arglist[numargs]=NULL;	
			execute( arglist );	
			numargs = 0;		
		}
	}
}
return 0;

}`