看看getopt到底是何方神圣。废话不多言，现在开始。
程序由于简单，就没有注释，将就看看啊。
/************************************
* filename: getopt.c
* author: GolenSoldier
* date: 2008.12.15
* version: 1.0
*************************************/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
extern int optind,opterr,optopt;
extern char *optarg;
void usage(void)
{
printf("Usage: /n");
printf(" Server:/n");
printf("/tvtund <-s> [-f file] [-P port] [-L local address]/n");
printf(" Client:/n");
printf("/tvtund [-f file] " /* [-P port] [-L local address] */
"[-p] [-m] [-t timeout] <host profile> <server address>/n");
}
int main(int argc, char *argv[])
{
int opt;
int svr = 0;
int svr_type = 0;
int daemon = 1;
int port = 5000;
int persist = 1;
int timeout = 30;
char *svr_addr = NULL;
char *cfg_file = NULL;
char *svr_name = NULL;
char *host;
while( (opt=getopt(argc, argv, "isf:P:L:t:np")) != EOF )
{
switch(opt)
{
case 'i':
svr_type = 1;
case 's':
svr = 1;
break;
case 'L':
svr_addr = strdup(optarg);
break;
case 'P':
port = atoi(optarg);
break;
case 'f':
cfg_file = strdup(optarg);
break;
case 'n':
daemon = 0;
break;
case 'p':
persist = 1;
break;
case 't':
timeout = atoi(optarg);
break;
default:
usage();
exit(1);
}
}
printf("optind is:%d./n", optind);
printf("optarg is:%s./n", optarg);
if (!svr)
{
if( argc - optind < 2 )
{
printf("arg - optind < 2!/n");
usage();
exit(1);
}
host = argv[optind++];
printf("client. host is %s./n", host);
svr_name = strdup(argv[optind]);
printf("srv_name is %s./n",svr_name);
}
else
printf("is server./n");
printf("svr is:%d./t"
"svr_type is:%d./t"
"daemon is:%d./t"
"port is:%d./t"
"persist is:%d./t"
"timeout is:%d./t"
"svr_addr is:%s./t"
"cfg_file is:%s./n",
svr, svr_type, daemon, port, persist, timeout, svr_addr, cfg_file);
exit(0);
}
RedHat 9 编译一下：
[root@root home]#gcc -Wall getopt.c -o getopt
下面是输入的测试的结果：
1
[root@root home]#./getopt
optind is:1.
optarg is:(null).
arg - optind < 2!
Usage:
Server:
vtund <-s> [-f file] [-P port] [-L local address]
Client:
vtund [-f file] [-p] [-m] [-t timeout] <host profile> <server address>
2
[root@root home]#./getopt -s cli
optind is:2.
optarg is:(null).
is server.
svr is:1. svr_type is:0. daemon is:1. port is:5000. persist is:1. timeout is:30. svr_addr is:(null). cfg_file is:(null).
3
[root@root home]#./getopt -s -i -f -P 110 -t 120
optind is:7.
optarg is:(null).
is server.
svr is:1. svr_type is:1. daemon is:1. port is:5000. persist is:1. timeout is:30. svr_addr is:(null). cfg_file is:-P.
4
[root@root home]#./getopt -s -f ab.c -p 110 -L 1.1.1.1
optind is:7.
optarg is:(null).
is server.
svr is:1. svr_type is:0. daemon is:1. port is:5000. persist is:1. timeout is:30. svr_addr is:1.1.1.1. cfg_file is:ab.c.
5
[root@root home]#./getopt cli
optind is:1.
optarg is:(null).
arg - optind < 2!
Usage:
Server:
vtund <-s> [-f file] [-P port] [-L local address]
Client:
vtund [-f file] [-p] [-m] [-t timeout] <host profile> <server address>
6
[root@root home]#./getopt cli 1.1.1.1
optind is:1.
optarg is:(null).
client. host is cli.
srv_name is 1.1.1.1.
svr is:0. svr_type is:0. daemon is:1. port is:5000. persist is:1. timeout is:30. svr_addr is:(null). cfg_file is:(null).
7
[root@root home]#./getopt cli -f ab.c -L 1.1.1.1 1.1.1.2
optind is:5.
optarg is:(null).
client. host is cli.
srv_name is 1.1.1.2.
svr is:0. svr_type is:0. daemon is:1. port is:5000. persist is:1. timeout is:30. svr_addr is:1.1.1.1. cfg_file is:ab.c.
总结：
关于 argc - optind < 2 语句就是为了客户端的<host profile> <server address>配置。换句话说，在客户端，只要是CASE中没有的，就会被认为是客户端的<host profile> <server address>配置，而在服务器端，就会被认为是输入差错。