myshell.c

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void make_toks(char *s, char *tok[])
{
	int i = 0;
	char *p;
	p = strtok(s, " ");
	while (p != NULL)
	{
		tok[i++] = p;
		p = strtok(NULL, " ");
	}
	tok[i] = NULL;
}
void count(char *fn, char op)
{
	int fh, cc = 0, wc = 0, lc = 0;
	char c;
	fh = open(fn, O_RDONLY);
	if (fh == -1)
	{
		printf("File %s not found.\n", fn);
		return;
	}
	while (read(fh, &c, 1) > 0)
	{
		if (c == ' ')
			wc++;
		else if (c == '\n')
		{
			wc++;
			lc++;
		}
		cc++;
	}
	close(fh);
	switch (op)
	{
	case 'c':
		printf("No.of characters:%d\n", cc - 1);
		break;
	case 'w':
		printf("No.of words:%d\n", wc);
		break;
	case 'l':
		printf("No.of lines:%d\n", lc + 1);
		break;
	}
}
int main()
{
	char buff[80], *args[10];
	int pid;
	while (1)
	{
		printf("myshell$ ");
		fflush(stdin);
		fgets(buff, 80, stdin);
		buff[strlen(buff) - 1] = '\0';
		make_toks(buff, args);
		if (strcmp(args[0], "count") == 0)
			count(args[2], args[1][0]);
		else
		{
			pid = fork();
			if (pid > 0)
				wait();
			else
			{
				if (execvp(args[0], args) == -1)
					printf("Bad command.\n");
			}
		}
	}
	return 0;
}