1. 函数介绍

用来解析命令行参数的。

函数原型

#include <unistd.h>int getopt(int argc, char * const argv[],const char *optstring);

第三个参数就是设置解析的参数。

假设$optstring="ab:c::"$

一个字母后面一个冒号表示，该字母选项必须带参数。
一个字母后面两个冒号表示，该字母可带参数可以不带参数。

假设你需要不带参数的选项h, 必须带参数的选项c，可带参数的选项d。

则optstring ="hc:d::"。

对于可选参数的传参需要注意，它需要直接跟在该选项后面，不能像必带参数选项一样。

即上面的d选项传参方式，-darg。

2. 使用例子

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>int main( int argc, char **argv)
{char *cv = NULL;int index;int c;char *dv = NULL;int af = 0;int bf = 0;int df = 0;opterr = 0;while ( (c = getopt( argc, argv, "abc:d::"))  != -1){switch (c){case 'a':af = 1;break;case 'b':bf = 1;break;case 'c':cv = optarg;break;case 'd':dv = optarg;df = 1;break;case '?':if ( optopt == 'c')fprintf( stderr, "Option -%c requires an argument.\n", optopt);else if ( isprint( optopt ))fprintf( stderr, "Unkown option `-%c` .\n", optopt);elsefprintf( stderr, "Unkown option character `\\x%x.\n`", optopt);default:abort();}}printf ( "aflag = %d, bflag = %d, cvalue = %s, df = %d ", af, bf, cv, df);if ( NULL != dv)printf("dvalue = %s", dv);printf("\n");for (index = optind; index < argc; index++)printf("Non-option argument %s\n", argv[index]);return 0;}

测试脚本

#! /bin/bash
./use_opt > test_opt.txt
./use_opt -a -b >> test_opt.txt
./use_opt -ab >> test_opt.txt
./use_opt -c foo >> test_opt.txt
./use_opt -a arg >> test_opt.txt
./use_opt -a -- -b >> test_opt.txt
./use_opt -d value >> test_opt.txt
./use_opt -dhello >> test_opt.txt

测试结果

aflag = 0, bflag = 0, cvalue = (null), df = 0
aflag = 1, bflag = 1, cvalue = (null), df = 0
aflag = 1, bflag = 1, cvalue = (null), df = 0
aflag = 0, bflag = 0, cvalue = foo, df = 0
aflag = 1, bflag = 0, cvalue = (null), df = 0
Non-option argument arg
aflag = 1, bflag = 0, cvalue = (null), df = 0
Non-option argument -b
aflag = 0, bflag = 0, cvalue = (null), df = 1
Non-option argument value
aflag = 0, bflag = 0, cvalue = (null), df = 1 dvalue = hello

3. 参考

linux-die
gnu-getop