psh2.c

//dadfasdf
#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>

#define MAXARGS 20
#define ARGLEN 100

char* makestring(char*);
void execute(char* []);

int main()
{
	char *arglist[MAXARGS+1];
	int numargs = 0;
	char argbuf[ARGLEN];

	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;
}

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);
	}
}

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;
}