shell 命令解析

The C programming language中一个简单的关于命令行参数的解析实例

#include <stdio.h>
#include <string.h>
#define MAXLINE 1000
int getline(char *line, int max);

#define MAXLINE 1000
int getline(char *line, int max);

int getline(char s[], int lim) {
	int c, i;
	i = 0;
	while (--lim > 0 && (c = getchar()) != EOF && c != '\n')
		s[i++] = c;
	if (c == '\n')
		s[i++] = c;
	s[i] = '\0';
	return i;
}

int main(int argc, char *argv[]) {
	char line[MAXLINE];
	long lineno = 0;
	int c, except = 0, number = 0, found = 0;
	while (--argc > 0 && (*++argv)[0] == '-')
		while ((c = *++argv[0]))
			switch (c) {
			case 'x':
				except = 1;
				break;
			case 'n':
				number = 1;
				break;
			default:
				printf("find: illegal option %c\n", c);
				argc = 0;
				found = -1;
				break;
			}
	if (argc != 1)
		printf("Usage: find -x -n pattern\n");
	else
		while ((getline(line, MAXLINE) > 0)) {
			lineno++;
			if ((strstr(line, *argv) != NULL )!= except) {
				if (number)
					printf("%ld:", lineno);
				printf("%s", line);
				found++;
			}
		}
	return found;
}